W3C

HTML 5

A vocabulary and associated APIs for HTML and XHTML

Editor's Draft 13 August 2009

Latest Published Version:
http://www.w3.org/TR/html5/
Latest Editor's Draft:
http://dev.w3.org/html5/rdfa/Overview.html
Previous Versions:
http://www.w3.org/TR/2009/WD-html5-20090423/
http://www.w3.org/TR/2009/WD-html5-20090212/
http://www.w3.org/TR/2008/WD-html5-20080610/
http://www.w3.org/TR/2008/WD-html5-20080122/
Editors:
Ian Hickson, Google, Inc.
David Hyatt, Apple, Inc.

Abstract

This specification defines the 5th major revision of the core language of the World Wide Web: the Hypertext Markup Language (HTML). In this version, new features are introduced to help Web application authors, new elements are introduced based on research into prevailing authoring practices, and special attention has been given to defining clear conformance criteria for user agents in an effort to improve interoperability.

Status of this document

This section describes the status of this document at the time of its publication. Other documents may supersede this document. A list of current W3C publications and the most recently formally published revision of this technical report can be found in the W3C technical reports index at http://www.w3.org/TR/.

The WHATWG version of this specification is available under a license that permits reuse of the specification text.

If you wish to make comments regarding this document, please send them to public-html-comments@w3.org (subscribe, archives) or whatwg@whatwg.org (subscribe, archives), or submit them using our public bug database. All feedback is welcome.

We maintain a list of all e-mails that have not yet been considered and a list of all bug reports that have not yet been resolved.

Implementors should be aware that this specification is not stable. Implementors who are not taking part in the discussions are likely to find the specification changing out from under them in incompatible ways. Vendors interested in implementing this specification before it eventually reaches the Candidate Recommendation stage should join the aforementioned mailing lists and take part in the discussions.

The publication of this document by the W3C as a W3C Working Draft does not imply that all of the participants in the W3C HTML working group endorse the contents of the specification. Indeed, for any section of the specification, one can usually find many members of the working group or of the W3C as a whole who object strongly to the current text, the existence of the section at all, or the idea that the working group should even spend time discussing the concept of that section.

The latest stable version of the editor's draft of this specification is always available on the W3C CVS server and in the WHATWG Subversion repository. The latest editor's working copy (which may contain unfinished text in the process of being prepared) is also available.

There are various ways to follow the change history for the specification:

E-mail notifications of changes
HTML-Diffs mailing list (diff-marked HTML versions for each change): http://lists.w3.org/Archives/Public/public-html-diffs/latest
Commit-Watchers mailing list (complete source diffs): http://lists.whatwg.org/listinfo.cgi/commit-watchers-whatwg.org
Real-time notifications of changes:
Generated diff-marked HTML versions for each change: http://twitter.com/HTML5
All (non-editorial) changes to the spec source: http://twitter.com/WHATWG
Browsable version-control record of all changes:
CVSWeb interface with side-by-side diffs: http://dev.w3.org/cvsweb/html5/spec/Overview.html
Annotated summary with unified diffs: http://html5.org/tools/web-apps-tracker
Raw Subversion interface: svn checkout http://svn.whatwg.org/webapps/

The W3C HTML Working Group is the W3C working group responsible for this specification's progress along the W3C Recommendation track. This specification is the 13 July 2009 Editor's Draft.

This specification is also being produced by the WHATWG. The two specifications are identical from the table of contents onwards.

This specification is intended to replace (be a new version of) what was previously the HTML4, XHTML 1.0, and DOM2 HTML specifications.

This document was produced by a group operating under the 5 February 2004 W3C Patent Policy. W3C maintains a public list of any patent disclosures made in connection with the deliverables of the group; that page also includes instructions for disclosing a patent. An individual who has actual knowledge of a patent which the individual believes contains Essential Claim(s) must disclose the information in accordance with section 6 of the W3C Patent Policy.

Stability

Different parts of this specification are at different levels of maturity.

Table of contents

  1. 1 Introduction
    1. 1.1 Background
    2. 1.2 Audience
    3. 1.3 Scope
    4. 1.4 History
    5. 1.5 Design notes
      1. 1.5.1 Serializability of script execution
      2. 1.5.2 Compliance with other specifications
    6. 1.6 Relationships to other specifications
      1. 1.6.1 Relationship to HTML 4.01 and DOM2 HTML
      2. 1.6.2 Relationship to XHTML 1.x
    7. 1.7 HTML vs XHTML
    8. 1.8 Structure of this specification
      1. 1.8.1 How to read this specification
      2. 1.8.2 Typographic conventions
    9. 1.9 A quick introduction to HTML
  2. 2 Common infrastructure
    1. 2.1 Terminology
      1. 2.1.1 Resources
      2. 2.1.2 XML
      3. 2.1.3 DOM trees
      4. 2.1.4 Scripting
      5. 2.1.5 Plugins
      6. 2.1.6 Character encodings
    2. 2.2 Conformance requirements
    3. 2.3 Case-sensitivity and string comparison
    4. 2.4 Common microsyntaxes
      1. 2.4.1 Boolean attributes
      2. 2.4.2 Keywords and enumerated attributes
      3. 2.4.3 Numbers
        1. 2.4.3.1 Non-negative integers
        2. 2.4.3.2 Signed integers
        3. 2.4.3.3 Real numbers
        4. 2.4.3.4 Ratios
        5. 2.4.3.5 Lists of integers
      4. 2.4.4 Dates and times
        1. 2.4.4.1 Months
        2. 2.4.4.2 Dates
        3. 2.4.4.3 Times
        4. 2.4.4.4 Local dates and times
        5. 2.4.4.5 Global dates and times
        6. 2.4.4.6 Weeks
        7. 2.4.4.7 Vaguer moments in time
      5. 2.4.5 Colors
      6. 2.4.6 Space-separated tokens
      7. 2.4.7 Comma-separated tokens
      8. 2.4.8 Reversed DNS identifiers
      9. 2.4.9 References
    5. 2.5 URLs
      1. 2.5.1 Terminology
      2. 2.5.2 Interfaces for URL manipulation
    6. 2.6 Common DOM interfaces
      1. 2.6.1 Reflecting content attributes in DOM attributes
      2. 2.6.2 Collections
        1. 2.6.2.1 HTMLCollection
        2. 2.6.2.2 HTMLAllCollection
        3. 2.6.2.3 HTMLFormControlsCollection
        4. 2.6.2.4 HTMLOptionsCollection
        5. 2.6.2.5 HTMLPropertyCollection
      3. 2.6.3 DOMTokenList
      4. 2.6.4 DOMSettableTokenList
      5. 2.6.5 DOMStringMap
      6. 2.6.6 DOM feature strings
      7. 2.6.7 Exceptions
  3. 3 Semantics, structure, and APIs of HTML documents
    1. 3.1 Introduction
    2. 3.2 Documents
      1. 3.2.1 Documents in the DOM
      2. 3.2.2 Security
      3. 3.2.3 Resource metadata management
      4. 3.2.4 DOM tree accessors
    3. 3.3 Elements
      1. 3.3.1 Semantics
      2. 3.3.2 Elements in the DOM
      3. 3.3.3 Global attributes
        1. 3.3.3.1 The id attribute
        2. 3.3.3.2 The title attribute
        3. 3.3.3.3 The lang and xml:lang attributes
        4. 3.3.3.4 The xml:base attribute (XML only)
        5. 3.3.3.5 The dir attribute
        6. 3.3.3.6 The class attribute
        7. 3.3.3.7 The style attribute
        8. 3.3.3.8 Embedding custom non-visible data
      4. 3.3.4 Element definitions
      5. 3.3.5 Content models
        1. 3.3.5.1 Kinds of content
          1. 3.3.5.1.1 Metadata content
          2. 3.3.5.1.2 Flow content
          3. 3.3.5.1.3 Sectioning content
          4. 3.3.5.1.4 Heading content
          5. 3.3.5.1.5 Phrasing content
          6. 3.3.5.1.6 Embedded content
          7. 3.3.5.1.7 Interactive content
        2. 3.3.5.2 Transparent content models
        3. 3.3.5.3 Paragraphs
    4. 3.4 APIs in HTML documents
    5. 3.5 Dynamic markup insertion
      1. 3.5.1 Controlling the input stream
      2. 3.5.2 document.write()
      3. 3.5.3 document.writeln()
      4. 3.5.4 innerHTML
      5. 3.5.5 outerHTML
      6. 3.5.6 insertAdjacentHTML()
  4. 4 The elements of HTML
    1. 4.1 The root element
      1. 4.1.1 The html element
    2. 4.2 Document metadata
      1. 4.2.1 The head element
      2. 4.2.2 The title element
      3. 4.2.3 The base element
      4. 4.2.4 The link element
      5. 4.2.5 The meta element
        1. 4.2.5.1 Standard metadata names
        2. 4.2.5.2 Other metadata names
        3. 4.2.5.3 Pragma directives
        4. 4.2.5.4 Other pragma directives
        5. 4.2.5.5 Specifying the document's character encoding
      6. 4.2.6 The style element
      7. 4.2.7 Styling
    3. 4.3 Scripting
      1. 4.3.1 The script element
        1. 4.3.1.1 Scripting languages
        2. 4.3.1.2 Inline documentation for external scripts
      2. 4.3.2 The noscript element
    4. 4.4 Sections
      1. 4.4.1 The body element
      2. 4.4.2 The section element
      3. 4.4.3 The nav element
      4. 4.4.4 The article element
      5. 4.4.5 The aside element
      6. 4.4.6 The h1, h2, h3, h4, h5, and h6 elements
      7. 4.4.7 The hgroup element
      8. 4.4.8 The header element
      9. 4.4.9 The footer element
      10. 4.4.10 The address element
      11. 4.4.11 Headings and sections
        1. 4.4.11.1 Creating an outline
        2. 4.4.11.2 Distinguishing site-wide headings from page headings
    5. 4.5 Grouping content
      1. 4.5.1 The p element
      2. 4.5.2 The hr element
      3. 4.5.3 The br element
      4. 4.5.4 The pre element
      5. 4.5.5 The dialog element
      6. 4.5.6 The blockquote element
      7. 4.5.7 The ol element
      8. 4.5.8 The ul element
      9. 4.5.9 The li element
      10. 4.5.10 The dl element
      11. 4.5.11 The dt element
      12. 4.5.12 The dd element
      13. 4.5.13 Common grouping idioms
        1. 4.5.13.1 Tag clouds
    6. 4.6 Text-level semantics
      1. 4.6.1 The a element
      2. 4.6.2 The q element
      3. 4.6.3 The cite element
      4. 4.6.4 The em element
      5. 4.6.5 The strong element
      6. 4.6.6 The small element
      7. 4.6.7 The mark element
      8. 4.6.8 The dfn element
      9. 4.6.9 The abbr element
      10. 4.6.10 The time element
      11. 4.6.11 The progress element
      12. 4.6.12 The meter element
      13. 4.6.13 The code element
      14. 4.6.14 The var element
      15. 4.6.15 The samp element
      16. 4.6.16 The kbd element
      17. 4.6.17 The sub and sup elements
      18. 4.6.18 The span element
      19. 4.6.19 The i element
      20. 4.6.20 The b element
      21. 4.6.21 The bdo element
      22. 4.6.22 The ruby element
      23. 4.6.23 The rt element
      24. 4.6.24 The rp element
      25. 4.6.25 Usage summary
      26. 4.6.26 Footnotes
    7. 4.7 Edits
      1. 4.7.1 The ins element
      2. 4.7.2 The del element
      3. 4.7.3 Attributes common to ins and del elements
      4. 4.7.4 Edits and paragraphs
      5. 4.7.5 Edits and lists
    8. 4.8 Embedded content
      1. 4.8.1 The figure element
      2. 4.8.2 The img element
        1. 4.8.2.1 Requirements for providing text to act as an alternative for images
          1. 4.8.2.1.1 A link or button containing nothing but the image
          2. 4.8.2.1.2 A phrase or paragraph with an alternative graphical representation: charts, diagrams, graphs, maps, illustrations
          3. 4.8.2.1.3 A short phrase or label with an alternative graphical representation: icons, logos
          4. 4.8.2.1.4 Text that has been rendered to a graphic for typographical effect
          5. 4.8.2.1.5 A graphical representation of some of the surrounding text
          6. 4.8.2.1.6 A purely decorative image that doesn't add any information
          7. 4.8.2.1.7 A group of images that form a single larger picture with no links
          8. 4.8.2.1.8 A group of images that form a single larger picture with links
          9. 4.8.2.1.9 A key part of the content
          10. 4.8.2.1.10 An image not intended for the user
          11. 4.8.2.1.11 An image in an e-mail or private document intended for a specific person who is known to be able to view images
          12. 4.8.2.1.12 General guidelines
      3. 4.8.3 The iframe element
      4. 4.8.4 The embed element
      5. 4.8.5 The object element
      6. 4.8.6 The param element
      7. 4.8.7 The video element
      8. 4.8.8 The audio element
      9. 4.8.9 The source element
      10. 4.8.10 Media elements
        1. 4.8.10.1 Error codes
        2. 4.8.10.2 Location of the media resource
        3. 4.8.10.3 MIME types
        4. 4.8.10.4 Network states
        5. 4.8.10.5 Loading the media resource
        6. 4.8.10.6 Offsets into the media resource
        7. 4.8.10.7 The ready states
        8. 4.8.10.8 Cue ranges
        9. 4.8.10.9 Playing the media resource
        10. 4.8.10.10 Seeking
        11. 4.8.10.11 User interface
        12. 4.8.10.12 Time ranges
        13. 4.8.10.13 Event summary
      11. 4.8.11 The canvas element
        1. 4.8.11.1 The 2D context
          1. 4.8.11.1.1 The canvas state
          2. 4.8.11.1.2 Transformations
          3. 4.8.11.1.3 Compositing
          4. 4.8.11.1.4 Colors and styles
          5. 4.8.11.1.5 Line styles
          6. 4.8.11.1.6 Shadows
          7. 4.8.11.1.7 Simple shapes (rectangles)
          8. 4.8.11.1.8 Complex shapes (paths)
          9. 4.8.11.1.9 Text
          10. 4.8.11.1.10 Images
          11. 4.8.11.1.11 Pixel manipulation
      12. 4.8.12 The map element
      13. 4.8.13 The area element
      14. 4.8.14 Image maps
      15. 4.8.15 MathML
      16. 4.8.16 SVG
      17. 4.8.17 Dimension attributes
    9. 4.9 Tabular data
      1. 4.9.1 Introduction
      2. 4.9.2 The table element
      3. 4.9.3 The caption element
      4. 4.9.4 The colgroup element
      5. 4.9.5 The col element
      6. 4.9.6 The tbody element
      7. 4.9.7 The thead element
      8. 4.9.8 The tfoot element
      9. 4.9.9 The tr element
      10. 4.9.10 The td element
      11. 4.9.11 The th element
      12. 4.9.12 Attributes common to td and th elements
    10. 4.10 Forms
      1. 4.10.1 The form element
      2. 4.10.2 The fieldset element
      3. 4.10.3 The label element
      4. 4.10.4 The input element
        1. 4.10.4.1 States of the type attribute
          1. 4.10.4.1.1 Hidden state
          2. 4.10.4.1.2 Text state and Search state
          3. 4.10.4.1.3 Telephone state
          4. 4.10.4.1.4 URL state
          5. 4.10.4.1.5 E-mail state
          6. 4.10.4.1.6 Password state
          7. 4.10.4.1.7 Date and Time state
          8. 4.10.4.1.8 Date state
          9. 4.10.4.1.9 Month state
          10. 4.10.4.1.10 Week state
          11. 4.10.4.1.11 Time state
          12. 4.10.4.1.12 Local Date and Time state
          13. 4.10.4.1.13 Number state
          14. 4.10.4.1.14 Range state
          15. 4.10.4.1.15 Color state
          16. 4.10.4.1.16 Checkbox state
          17. 4.10.4.1.17 Radio Button state
          18. 4.10.4.1.18 File Upload state
          19. 4.10.4.1.19 Submit Button state
          20. 4.10.4.1.20 Image Button state
          21. 4.10.4.1.21 Reset Button state
          22. 4.10.4.1.22 Button state
        2. 4.10.4.2 Common input element attributes
          1. 4.10.4.2.1 The autocomplete attribute
          2. 4.10.4.2.2 The list attribute
          3. 4.10.4.2.3 The readonly attribute
          4. 4.10.4.2.4 The size attribute
          5. 4.10.4.2.5 The required attribute
          6. 4.10.4.2.6 The multiple attribute
          7. 4.10.4.2.7 The maxlength attribute
          8. 4.10.4.2.8 The pattern attribute
          9. 4.10.4.2.9 The min and max attributes
          10. 4.10.4.2.10 The step attribute
          11. 4.10.4.2.11 The placeholder attribute
        3. 4.10.4.3 Common input element APIs
      5. 4.10.5 The button element
      6. 4.10.6 The select element
      7. 4.10.7 The datalist element
      8. 4.10.8 The optgroup element
      9. 4.10.9 The option element
      10. 4.10.10 The textarea element
      11. 4.10.11 The keygen element
      12. 4.10.12 The output element
      13. 4.10.13 Association of controls and forms
      14. 4.10.14 Attributes common to form controls
        1. 4.10.14.1 Naming form controls
        2. 4.10.14.2 Enabling and disabling form controls
        3. 4.10.14.3 Autofocusing a form control
        4. 4.10.14.4 Limiting user input length
        5. 4.10.14.5 Form submission
      15. 4.10.15 Constraints
        1. 4.10.15.1 Definitions
        2. 4.10.15.2 The constraint validation API
      16. 4.10.16 Form submission
    11. 4.11 Interactive elements
      1. 4.11.1 The details element
      2. 4.11.2 The command element
      3. 4.11.3 The bb element
        1. 4.11.3.1 Browser button types
          1. 4.11.3.1.1 The make application state
      4. 4.11.4 The menu element
        1. 4.11.4.1 Introduction
        2. 4.11.4.2 Context menus
      5. 4.11.5 Commands
    12. 4.12 Miscellaneous elements
      1. 4.12.1 The legend element
      2. 4.12.2 The div element
  5. 5 Microdata
    1. 5.1 Introduction
      1. 5.1.1 The basic syntax
      2. 5.1.2 Typed items
      3. 5.1.3 Selecting names when defining vocabularies
      4. 5.1.4 Using the microdata DOM API
    2. 5.2 Encoding microdata
      1. 5.2.1 The microdata model
      2. 5.2.2 Items: the item attribute
      3. 5.2.3 Associating names with items
      4. 5.2.4 Names: the itemprop attribute
      5. 5.2.5 Values
    3. 5.3 Microdata DOM API
    4. 5.4 Predefined vocabularies
      1. 5.4.1 General
      2. 5.4.2 vCard
        1. 5.4.2.1 Examples
      3. 5.4.3 vEvent
        1. 5.4.3.1 Examples
      4. 5.4.4 Licensing works
        1. 5.4.4.1 Examples
  6. 6 Web browsers
    1. 6.1 Browsing contexts
      1. 6.1.1 Nested browsing contexts
        1. 6.1.1.1 Navigating nested browsing contexts in the DOM
      2. 6.1.2 Auxiliary browsing contexts
        1. 6.1.2.1 Navigating auxiliary browsing contexts in the DOM
      3. 6.1.3 Secondary browsing contexts
      4. 6.1.4 Browsing context names
    2. 6.2 The Window object
      1. 6.2.1 APIs for creating and navigating browsing contexts by name
      2. 6.2.2 Accessing other browsing contexts
      3. 6.2.3 Named access on the Window object
      4. 6.2.4 Browser interface elements
      5. 6.2.5 Relaxing the same-origin restriction
    3. 6.3 Scripting
      1. 6.3.1 Introduction
      2. 6.3.2 Events
    4. 6.4 Timers
    5. 6.5 User prompts
      1. 6.5.1 Simple dialogs
      2. 6.5.2 Printing
      3. 6.5.3 Dialogs implemented using separate documents
    6. 6.6 System state and capabilities
      1. 6.6.1 Client identification
      2. 6.6.2 Custom scheme and content handlers
      3. 6.6.3 Manually releasing the storage mutex
    7. 6.7 Offline Web applications
      1. 6.7.1 Introduction
        1. 6.7.1.1 Event summary
      2. 6.7.2 The cache manifest syntax
        1. 6.7.2.1 A sample manifest
        2. 6.7.2.2 Writing cache manifests
      3. 6.7.3 Expiring application caches
      4. 6.7.4 Application cache API
      5. 6.7.5 Browser state
    8. 6.8 Session history and navigation
      1. 6.8.1 The session history of browsing contexts
      2. 6.8.2 The History interface
      3. 6.8.3 Activating state object entries
      4. 6.8.4 The Location interface
    9. 6.9 Browsing the Web
      1. 6.9.1 Unloading documents
    10. 6.10 Links
      1. 6.10.1 Hyperlink elements
      2. 6.10.2 Link types
        1. 6.10.2.1 Link type "alternate"
        2. 6.10.2.2 Link type "archives"
        3. 6.10.2.3 Link type "author"
        4. 6.10.2.4 Link type "bookmark"
        5. 6.10.2.5 Link type "external"
        6. 6.10.2.6 Link type "feed"
        7. 6.10.2.7 Link type "help"
        8. 6.10.2.8 Link type "icon"
        9. 6.10.2.9 Link type "license"
        10. 6.10.2.10 Link type "nofollow"
        11. 6.10.2.11 Link type "noreferrer"
        12. 6.10.2.12 Link type "pingback"
        13. 6.10.2.13 Link type "prefetch"
        14. 6.10.2.14 Link type "search"
        15. 6.10.2.15 Link type "stylesheet"
        16. 6.10.2.16 Link type "sidebar"
        17. 6.10.2.17 Link type "tag"
        18. 6.10.2.18 Hierarchical link types
          1. 6.10.2.18.1 Link type "index"
          2. 6.10.2.18.2 Link type "up"
        19. 6.10.2.19 Sequential link types
          1. 6.10.2.19.1 Link type "first"
          2. 6.10.2.19.2 Link type "last"
          3. 6.10.2.19.3 Link type "next"
          4. 6.10.2.19.4 Link type "prev"
        20. 6.10.2.20 Other link types
  7. 7 User Interaction
    1. 7.1 Introduction
    2. 7.2 The hidden attribute
    3. 7.3 Activation
    4. 7.4 Scrolling elements into view
    5. 7.5 Focus
      1. 7.5.1 Sequential focus navigation
      2. 7.5.2 Document-level focus APIs
      3. 7.5.3 Element-level focus APIs
    6. 7.6 The accesskey attribute
    7. 7.7 The text selection APIs
      1. 7.7.1 APIs for the browsing context selection
      2. 7.7.2 APIs for the text field selections
    8. 7.8 The contenteditable attribute
      1. 7.8.1 Making entire documents editable
    9. 7.9 Spelling and grammar checking
    10. 7.10 Drag and drop
      1. 7.10.1 Introduction
      2. 7.10.2 The DragEvent and DataTransfer interfaces
      3. 7.10.3 Events fired during a drag-and-drop action
      4. 7.10.4 The draggable attribute
      5. 7.10.5 Copy and paste
    11. 7.11 Undo history
      1. 7.11.1 Introduction
      2. 7.11.2 The UndoManager interface
      3. 7.11.3 The UndoManagerEvent interface and the undo and redo events
    12. 7.12 Editing APIs
  8. 8 Communication
    1. 8.1 Event definitions
    2. 8.2 Cross-document messaging
      1. 8.2.1 Introduction
      2. 8.2.2 Security
      3. 8.2.3 Posting messages
    3. 8.3 Channel messaging
      1. 8.3.1 Introduction
      2. 8.3.2 Message channels
      3. 8.3.3 Message ports
        1. 8.3.3.1 Ports and garbage collection
  9. 9 The HTML syntax
    1. 9.1 Writing HTML documents
      1. 9.1.1 The DOCTYPE
      2. 9.1.2 Elements
        1. 9.1.2.1 Start tags
        2. 9.1.2.2 End tags
        3. 9.1.2.3 Attributes
        4. 9.1.2.4 Optional tags
        5. 9.1.2.5 Restrictions on content models
        6. 9.1.2.6 Restrictions on the contents of raw text and RCDATA elements
      3. 9.1.3 Text
        1. 9.1.3.1 Newlines
      4. 9.1.4 Character references
      5. 9.1.5 CDATA sections
      6. 9.1.6 Comments
    2. 9.2 Named character references
  10. 10 The XHTML syntax
    1. 10.1 Selectors
  11. 11 Obsolete features
    1. 11.1 Obsolete but conforming features
    2. 11.2 Non-conforming features
  12. 12 Things that you can't do with this specification because they are better handled using other technologies that are further described herein
    1. 12.1 Localization
    2. 12.2 Declarative 3D scenes
  13. IANA considerations
    1. 12.1 text/html
    2. 12.2 application/xhtml+xml
    3. 12.3 text/cache-manifest
    4. 12.4 text/ping
    5. 12.5 application/microdata+json
  14. Index
  15. References
  16. Acknowledgements

1 Introduction

Status: Working draft

1.1 Background

This section is non-normative.

The World Wide Web's markup language has always been HTML. HTML was primarily designed as a language for semantically describing scientific documents, although its general design and adaptations over the years have enabled it to be used to describe a number of other types of documents.

The main area that has not been adequately addressed by HTML is a vague subject referred to as Web Applications. This specification attempts to rectify this, while at the same time updating the HTML specifications to address issues raised in the past few years.

1.2 Audience

This section is non-normative.

This specification is intended for authors of documents and scripts that use the features defined in this specification, implementors of tools that operate on pages that use the features defined in this specification, and individuals wishing to establish the correctness of documents or implementations with respect to the requirements of this specification

This document is probably not suited to readers who do not already have at least a passing familiarity with Web technologies, as in places it sacrifices clarity for precision, and brevity for completeness. More approachable tutorials and authoring guides can provide a gentler introduction to the topic.

In particular, familiarity with the basics of DOM Core and DOM Events is necessary for a complete understanding of some of the more technical parts of this specification. An understanding of Web IDL, HTTP, XML, Unicode, character encodings, JavaScript, and CSS will also be helpful in places but is not essential.

1.3 Scope

This section is non-normative.

This specification is limited to providing a semantic-level markup language and associated semantic-level scripting APIs for authoring accessible pages on the Web ranging from static documents to dynamic applications.

The scope of this specification does not include providing mechanisms for media-specific customization of presentation (although default rendering rules for Web browsers are included at the end of this specification, and several mechanisms for hooking into CSS are provided as part of the language).

The scope of this specification does not include documenting every HTML or DOM feature supported by Web browsers. Browsers support many features that are considered to be very bad for accessibility or that are otherwise inappropriate. For example, the blink element is clearly presentational and authors wishing to cause text to blink should instead use CSS.

The scope of this specification is not to describe an entire operating system. In particular, hardware configuration software, image manipulation tools, and applications that users would be expected to use with high-end workstations on a daily basis are out of scope. In terms of applications, this specification is targeted specifically at applications that would be expected to be used by users on an occasional basis, or regularly but from disparate locations, with low CPU requirements. For instance online purchasing systems, searching systems, games (especially multiplayer online games), public telephone books or address books, communications software (e-mail clients, instant messaging clients, discussion software), document editing software, etc.

1.4 History

This section is non-normative.

Work on HTML 5 originally started in late 2003, as a proof of concept to show that it was possible to extend HTML 4's forms to provide many of the features that XForms 1.0 introduced, without requiring browsers to implement rendering engines that were incompatible with existing HTML Web pages. At this early stage, while the draft was already publicly available, and input was already being solicited from all sources, the specification was only under Opera Software's copyright.

In early 2004, some of the principles that underlie this effort, as well as an early draft proposal covering just forms-related features, were presented to the W3C jointly by Mozilla and Opera at a workshop discussing the future of Web Applications on the Web. The proposal was rejected on the grounds that the proposal conflicted with the previously chosen direction for the Web's evolution.

Shortly thereafter, Apple, Mozilla, and Opera jointly announced their intent to continue working on the effort. A public mailing list was created, and the drafts were moved to the WHATWG site. The copyright was subsequently amended to be jointly owned by all three vendors, and to allow reuse of the specifications.

In 2006, the W3C expressed interest in the specification, and created a working group chartered to work with the WHATWG on the development of the HTML 5 specifications. The working group opened in 2007. Apple, Mozilla, and Opera allowed the W3C to publish the specifications under the W3C copyright, while keeping versions with the less restrictive license on the WHATWG site.

Since then, both groups have been working together.

1.5 Design notes

This section is non-normative.

It must be admitted that many aspects of HTML appear at first glance to be nonsensical and inconsistent.

HTML, its supporting DOM APIs, as well as many of its supporting technologies, have been developed over a period of several decades by a wide array of people with different priorities who, in many cases, did not know of each other's existence.

Features have thus arisen from many sources, and have not always been designed in especially consistent ways. Furthermore, because of the unique characteristics of the Web, implementation bugs have often become de-facto, and now de-jure, standards, as content is often unintentionally written in ways that rely on them before they can be fixed.

Despite all this, efforts have been made to adhere to certain design goals. These are described in the next few subsections.

1.5.1 Serializability of script execution

This section is non-normative.

To avoid exposing Web authors to the complexities of multithreading, the HTML and DOM APIs are designed such that no script can ever detect the simultaneous execution of other scripts. Even with workers, the intent is that the behavior of implementations can be thought of as completely serialising the execution of all scripts in all browsing contexts.

The navigator.getStorageUpdates() method, in this model, is equivalent to allowing other scripts to run while the calling script is blocked.

1.5.2 Compliance with other specifications

This section is non-normative.

This specification interacts with and relies on a wide variety of other specifications. In certain circumstances, unfortunately, the desire to be compatible with legacy content has led to this specification violating the requirements of these other specifications. Whenever this has occurred, the transgressions have been noted as "willful violations".

1.6 Relationships to other specifications

1.6.1 Relationship to HTML 4.01 and DOM2 HTML

Status: Working draft

This section is non-normative.

This specification describes a new revision of the HTML language and its associated DOM API.

The requirements in this specification for features that were already in HTML 4 and DOM2 HTML are based primarily on the implementation and deployment experience collected over the past ten years. Some features have been removed from the language, based on best current practices; implementation requirements for some of these, as well as for non-standard features that have nonetheless garnered wide use, are still included in this specification to allow implementations to continue supporting legacy content. [HTML4] [DOM2HTML]

A separate document has been published by the W3C HTML working group to provide a more detailed reference of the differences between this specification and the language described in the HTML 4 specification. [HTMLDIFF]

1.6.2 Relationship to XHTML 1.x

Status: Working draft

This section is non-normative.

This specification is intended to replace XHTML 1.0 as the normative definition of the XML serialization of the HTML vocabulary. [XHTML10]

While this specification updates the semantics and requirements of the vocabulary defined by XHTML Modularization 1.1 and used by XHTML 1.1, it does not attempt to provide a replacement for the modularization scheme defined and used by those (and other) specifications, and therefore cannot be considered a complete replacement for them. [XHTMLMOD] [XHTML11]

Thus, authors and implementors who do not need such a modularization scheme can consider this specification a replacement for XHTML 1.x, but those who do need such a mechanism are encouraged to continue using the XHTML 1.1 line of specifications.

1.7 HTML vs XHTML

Status: Controversial Working Draft

This section is non-normative.

This specification defines an abstract language for describing documents and applications, and some APIs for interacting with in-memory representations of resources that use this language.

The in-memory representation is known as "DOM5 HTML", or "the DOM" for short.

There are various concrete syntaxes that can be used to transmit resources that use this abstract language, two of which are defined in this specification.

The first such concrete syntax is "HTML5". This is the format recommended for most authors. It is compatible with all legacy Web browsers. If a document is transmitted with the MIME type text/html, then it will be processed as an "HTML5" document by Web browsers.

The second concrete syntax uses XML, and is known as "XHTML5". When a document is transmitted with an XML MIME type, such as application/xhtml+xml, then it is processed by an XML processor by Web browsers, and treated as an "XHTML5" document. Authors are reminded that the processing for XML and HTML differs; in particular, even minor syntax errors will prevent an XML document from being rendered fully, whereas they would be ignored in the "HTML5" syntax.

The "DOM5 HTML", "HTML5", and "XHTML5" representations cannot all represent the same content. For example, namespaces cannot be represented using "HTML5", but they are supported in "DOM5 HTML" and "XHTML5". Similarly, documents that use the noscript feature can be represented using "HTML5", but cannot be represented with "XHTML5" and "DOM5 HTML". Comments that contain the string "-->" can be represented in "DOM5 HTML" but not in "HTML5" and "XHTML5". And so forth.

1.8 Structure of this specification

This section is non-normative.

This specification is divided into the following major sections:

Common Infrastructure
The conformance classes, algorithms, definitions, and the common underpinnings of the rest of the specification.
Semantics, structure, and APIs of HTML documents
Documents are built from elements. These elements form a tree using the DOM. This section defines the features of this DOM, as well as introducing the features common to all elements, and the concepts used in defining elements.
Elements
Each element has a predefined meaning, which is explained in this section. Rules for authors on how to use the element, along with user agent requirements for how to handle each element,
Microdata
This specification introduces a mechanism for adding machine-readable annotations to documents, so that tools can extract trees of name/value pairs from the document. This section describes this mechanism and some algorithms that can be used to convert HTML documents into other formats
Web Browsers
HTML documents do not exist in a vacuum — this section defines many of the features that affect environments that deal with multiple pages, links between pages, and running scripts.
User Interaction
HTML documents can provide a number of mechanisms for users to interact with and modify content, which are described in this section.
The Communication APIs
This section describes some mechanisms that applications written in HTML can use to communicate with other applications from different domains running on the same client.
The HTML Syntax
The XHTML Syntax
All of these features would be for naught if they couldn't be represented in a serialized form and sent to other people, and so these sections define the syntaxes of HTML, along with rules for how to parse content using those syntaxes.

There are also a couple of appendices, defining rendering rules for Web browsers and listing obsolete features and areas that are out of scope for this specification.

1.8.1 How to read this specification

This specification should be read like all other specifications. First, it should be read cover-to-cover, multiple times. Then, it should be read backwards at least once. Then it should be read by picking random sections from the contents list and following all the cross-references.

1.8.2 Typographic conventions

Status: Implemented and widely deployed

This is a definition, requirement, or explanation.

This is a note.

This is an example.

This is an open issue.

This is a warning.

interface Example {
  // this is an IDL definition
};
variable = object . method( [ optionalArgument ] )

This is a note to authors describing the usage of an interface.

/* this is a CSS fragment */

The defining instance of a term is marked up like this. Uses of that term are marked up like this or like this.

The defining instance of an element, attribute, or API is marked up like this. References to that element, attribute, or API are marked up like this.

Other code fragments are marked up like this.

Variables are marked up like this.

1.9 A quick introduction to HTML

Status: Last call for comments

This section is non-normative.

A basic HTML document looks like this:

<!DOCTYPE HTML>
<html>
 <head>
  <title>Sample page</title>
 </head>
 <body>
  <h1>Sample page</h1>
  <p>This is a <a href="demo.html">simple</a> sample.</p>
  <!-- this is a comment -->
 </body>
</html>

HTML documents consist of a tree of elements and text. Each element is denoted in the source by a start tag, such as "<body>", and an end tag, such as "</body>". (Certain start tags and end tags can in certain cases be omitted and are implied by other tags.)

Tags have to be nested such that elements are all completely within each other, without overlapping:

<p>This is <em>very <strong>wrong</em>!</strong></p>
<p>This <em>is <strong>correct</strong>.</em></p>

This specification defines a set of elements that can be used in HTML, along with rules about the ways in which the elements can be nested.

Elements can have attributes, which control how the elements work. In the example above, there is a hyperlink, formed using the a element and its href attribute:

<a href="demo.html">simple</a>

Attributes are placed inside the start tag, and consist of a name and a value, separated by an "=" character. The attribute value can be left unquoted if it doesn't contain any special characters. Otherwise, it has to be quoted using either single or double quotes. The value, along with the "=" character, can be omitted altogether if the value is the empty string.

<!-- empty attributes -->
<input name=address disabled>
<input name=address disabled="">

<!-- attributes with a value -->
<input name=address maxlength=200>
<input name=address maxlength='200'>
<input name=address maxlength="200">

HTML user agents (e.g. Web browsers) then parse this markup, turning it into a DOM (Document Object Model) tree. A DOM tree is an in-memory representation of a document.

DOM trees contain several kinds of nodes, in particular a DOCTYPE node, elements, text nodes, and comment nodes.

The markup snippet at the top of this section would be turned into the following DOM tree:

The root element of this tree is the html element, which is the element always found at the root of HTML documents. It contains two elements, head and body, as well as a text node between them.

There are many more text nodes in the DOM tree than one would initially expect, because the source contains a number of spaces (presented by "␣") and line breaks ("⏎") that all end up as text nodes in the DOM.

The head element contains a title element, which itself contains a text node with the text "Sample page". Similarly, the body element contains an h1 element, a p element, and a comment.


This DOM tree can be manipulated from scripts in the page. Scripts (typically in JavaScript) are small programs that can be embedded using the script element or using event handler content attributes. For example, here is a form with a script that sets the value of the form's output element to say "Hello World":

<form name="main">
 Result: <output name="result"></output>
 <script>
  document.forms.main.elements.result.value = 'Hello World';
 </script>
</form>

Each element in the DOM tree is represented by an object, and these objects have APIs so that they can be manipulated. For instance, a link (e.g. the a element in the tree above) can have its "href" attributed changed in several ways:

var a = document.links[0]; // obtain the first link in the document
a.href = 'sample.html'; // change the destination URL of the link
a.protocol = 'https'; // change just the scheme part of the URL
a.setAttribute('href', 'http://example.com/'); // change the content attribute directly

Since DOM trees are used as the way to represent HTML documents when they are processed and presented by implementations (especially interactive implementations like Web browsers), this specification is mostly phrased in terms of DOM trees, instead of the markup described above.


HTML documents represent a media-independent description of interactive content. HTML documents might be rendered to a screen, or through a speech synthesizer, or on a braille display. To influence exactly how such rendering takes place, authors can use a styling language such as CSS.

In the following example, the page has been made yellow-on-blue using CSS.

<!DOCTYPE HTML>
<html>
 <head>
  <title>Sample styled page</title>
  <style>
   body { background: navy; color: yellow; }
  </style>
 </head>
 <body>
  <h1>Sample styled page</h1>
  <p>This page is just a demo.</p>
 </body>
</html>

For more details on how to use HTML, authors are encouraged to consult tutorials and guides. Some of the examples included in this specification might also be of use, but the novice author is cautioned that this specification, by necessity, defines the language with a level of detail that may be difficult to understand at first.

2 Common infrastructure

2.1 Terminology

Status: Working draft

This specification refers to both HTML and XML attributes and DOM attributes, often in the same context. When it is not clear which is being referred to, they are referred to as content attributes for HTML and XML attributes, and DOM attributes for those from the DOM. Similarly, the term "properties" is used for both JavaScript object properties and CSS properties. When these are ambiguous they are qualified as object properties and CSS properties respectively.

Generally, when the specification states that a feature applies to the HTML syntax or the XHTML syntax, it also includes the other. When a feature specifically only applies to one of the two languages, it is called out by explicitly stating that it does not apply to the other format, as in "for HTML, ... (this does not apply to XHTML)".

This specification uses the term document to refer to any use of HTML, ranging from short static documents to long essays or reports with rich multimedia, as well as to fully-fledged interactive applications.

For simplicity, terms such as shown, displayed, and visible might sometimes be used when referring to the way a document is rendered to the user. These terms are not meant to imply a visual medium; they must be considered to apply to other media in equivalent ways.

When an algorithm B says to return to another algorithm A, it implies that A called B. Upon returning to A, the implementation must continue from where it left off in calling B.

2.1.1 Resources

The specification uses the term supported when referring to whether a user agent has an implementation capable of decoding the semantics of an external resource. A format or type is said to be supported if the implementation can process an external resource of that format or type without critical aspects of the resource being ignored. Whether a specific resource is supported can depend on what features of the resource's format are in use.

For example, a PNG image would be considered to be in a supported format if its pixel data could be decoded and rendered, even if, unbeknownst to the implementation, the image actually also contained animation data.

A MPEG4 video file would not be considered to be in a supported format if the compression format used was not supported, even if the implementation could determine the dimensions of the movie from the file's metadata.

The term MIME type is used to refer to what is sometimes called an Internet media type in protocol literature. The term media type in this specification is used to refer to the type of media intended for presentation, as used by the CSS specifications. [RFC2046] [MQ]

A string is a valid MIME type if it matches the media-type token defined in section 3.7 "Media Types" of RFC 2616. [HTTP]

2.1.2 XML

Status: Working draft

To ease migration from HTML to XHTML, UAs conforming to this specification will place elements in HTML in the http://www.w3.org/1999/xhtml namespace, at least for the purposes of the DOM and CSS. The term "elements in the HTML namespace", or "HTML elements" for short, when used in this specification, thus refers to both HTML and XHTML elements.

Unless otherwise stated, all elements defined or mentioned in this specification are in the http://www.w3.org/1999/xhtml namespace, and all attributes defined or mentioned in this specification have no namespace (they are in the per-element partition).

When an XML name, such as an attribute or element name, is referred to in the form prefix:localName, as in xml:id or svg:rect, it refers to a name with the local name localName and the namespace given by the prefix, as defined by the following table:

xml
http://www.w3.org/XML/1998/namespace
html
http://www.w3.org/1999/xhtml
svg
http://www.w3.org/2000/svg

Attribute names are said to be XML-compatible if they match the Name production defined in XML, they contain no U+003A COLON (:) characters, and their first three characters are not an ASCII case-insensitive match for the string "xml". [XML]

The term XML MIME type is used to refer to the MIME types text/xml, application/xml, and any MIME type ending with the four characters "+xml". [RFC3023]

2.1.3 DOM trees

The term root element, when not explicitly qualified as referring to the document's root element, means the furthest ancestor element node of whatever node is being discussed, or the node itself if it has no ancestors. When the node is a part of the document, then that is indeed the document's root element; however, if the node is not currently part of the document tree, the root element will be an orphaned node.

A node's home subtree is the subtree rooted at that node's root element.

The Document of a Node (such as an element) is the Document that the Node's ownerDocument DOM attribute returns.

When an element's root element is the root element of a Document, it is said to be in a Document. An element is said to have been inserted into a document when its root element changes and is now the document's root element. Analogously, an element is said to have been removed from a document when its root element changes from being the document's root element to being another element.

If a Node is in a Document then that Document is always the Node's Document, and the Node's ownerDocument DOM attribute thus always returns that Document.

The term tree order means a pre-order, depth-first traversal of DOM nodes involved (through the parentNode/childNodes relationship).

When it is stated that some element or attribute is ignored, or treated as some other value, or handled as if it was something else, this refers only to the processing of the node after it is in the DOM.

The term text node refers to any Text node, including CDATASection nodes; specifically, any Node with node type TEXT_NODE (3) or CDATA_SECTION_NODE (4). [DOMCORE]

A content attribute is said to change value only if its new value is different than its previous value; setting an attribute to a value it already has does not change it.

2.1.4 Scripting

The construction "a Foo object", where Foo is actually an interface, is sometimes used instead of the more accurate "an object implementing the interface Foo".

A DOM attribute is said to be getting when its value is being retrieved (e.g. by author script), and is said to be setting when a new value is assigned to it.

If a DOM object is said to be live, then that means that any attributes returning that object always return the same object (not a new object each time), and the attributes and methods on that object operate on the actual underlying data, not a snapshot of the data.

The terms fire and dispatch are used interchangeably in the context of events, as in the DOM Events specifications. [DOMEVENTS]

2.1.5 Plugins

The term plugin is used to mean any content handler for Web content types that are either not supported by the user agent natively or that do not expose a DOM, which supports rendering the content as part of the user agent's interface.

Typically such content handlers are provided by third parties.

One example of a plugin would be a PDF viewer that is instantiated in a browsing context when the user navigates to a PDF file. This would count as a plugin regardless of whether the party that implemented the PDF viewer component was the same as that which implemented the user agent itself. However, a PDF viewer application that launches separate from the user agent (as opposed to using the same interface) is not a plugin by this definition.

This specification does not define a mechanism for interacting with plugins, as it is expected to be user-agent- and platform-specific. Some UAs might opt to support a plugin mechanism such as the Netscape Plugin API; others might use remote content converters or have built-in support for certain types. [NPAPI]

Browsers should take extreme care when interacting with external content intended for plugins. When third-party software is run with the same privileges as the user agent itself, vulnerabilities in the third-party software become as dangerous as those in the user agent.

2.1.6 Character encodings

An ASCII-compatible character encoding is a single-byte or variable-length encoding in which the bytes 0x09, 0x0A, 0x0C, 0x0D, 0x20 - 0x22, 0x26, 0x27, 0x2C - 0x3F, 0x41 - 0x5A, and 0x61 - 0x7A, ignoring bytes that are the second and later bytes of multibyte sequences, all correspond to single-byte sequences that map to the same Unicode characters as those bytes in ANSI_X3.4-1968 (US-ASCII). [RFC1345]

This includes such encodings as Shift_JIS and variants of ISO-2022, even though it is possible in these encodings for bytes like 0x70 to be part of longer sequences that are unrelated to their interpretation as ASCII. It excludes such encodings as UTF-7, UTF-16, HZ-GB-2312, GSM03.38, and EBCDIC variants.

2.2 Conformance requirements

Status: Working draft

All diagrams, examples, and notes in this specification are non-normative, as are all sections explicitly marked non-normative. Everything else in this specification is normative.

The key words "MUST", "MUST NOT", "REQUIRED", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in the normative parts of this document are to be interpreted as described in RFC2119. For readability, these words do not appear in all uppercase letters in this specification. [RFC2119]

This specification describes the conformance criteria for user agents (relevant to implementors) and (relevant to authors and authoring tool implementors)

For compatibility with existing content and prior specifications, this specification describes two authoring formats: one based on XML (referred to as the XHTML syntax), and one using a custom format inspired by SGML (referred to as the HTML syntax).

XML documents that use elements or attributes from the HTML namespace and that are served over the wire (e.g. by HTTP) must be sent using an XML MIME type such as application/xml or application/xhtml+xml and must not be served as text/html. [RFC3023]

Documents that use the HTML syntax, if they are served over the wire (e.g. by HTTP) must be labeled with the text/html MIME type.

2.3 Case-sensitivity and string comparison

Status: Working draft

This specification defines several comparison operators for strings.

Comparing two strings in a case-sensitive manner means comparing them exactly, code point for code point.

Comparing two strings in an ASCII case-insensitive manner means comparing them exactly, code point for code point, except that the characters in the range U+0041 .. U+005A (i.e. LATIN CAPITAL LETTER A to LATIN CAPITAL LETTER Z) and the corresponding characters in the range U+0061 .. U+007A (i.e. LATIN SMALL LETTER A to LATIN SMALL LETTER Z) are considered to also match.

Comparing two strings in a compatibility caseless manner means using the Unicode compatibility caseless match operation to compare the two strings. [UNICODE]

A string pattern is a prefix match for a string s when pattern is not longer than s and truncating s to pattern's length leaves the two strings as matches of each other.

2.4 Common microsyntaxes

Status: Working draft

There are various places in HTML that accept particular data types, such as dates or numbers. This section describes what the conformance criteria for content in those formats is, and how to parse them.

2.4.1 Boolean attributes

A number of attributes are boolean attributes. The presence of a boolean attribute on an element represents the true value, and the absence of the attribute represents the false value.

If the attribute is present, its value must either be the empty string or a value that is an ASCII case-insensitive match for the attribute's canonical name, with no leading or trailing whitespace.

The values "true" and "false" are not allowed on boolean attributes. To represent a false value, the attribute has to be omitted altogether.

2.4.2 Keywords and enumerated attributes

Some attributes are defined as taking one of a finite set of keywords. Such attributes are called enumerated attributes. The keywords are each defined to map to a particular state (several keywords might map to the same state, in which case some of the keywords are synonyms of each other; additionally, some of the keywords can be said to be non-conforming, and are only in the specification for historical reasons). In addition, two default states can be given. The first is the invalid value default, the second is the missing value default.

If an enumerated attribute is specified, the attribute's value must be an ASCII case-insensitive match for one of the given keywords that are not said to be non-conforming, with no leading or trailing whitespace.

When the attribute is specified, if its value is an ASCII case-insensitive match for one of the given keywords then that keyword's state is the state that the attribute represents. If the attribute value matches none of the given keywords, but the attribute has an invalid value default, then the attribute represents that state. Otherwise, if the attribute value matches none of the keywords but there is a missing value default state defined, then that is the state represented by the attribute. Otherwise, there is no default, and invalid values must be ignored.

When the attribute is not specified, if there is a missing value default state defined, then that is the state represented by the (missing) attribute. Otherwise, the absence of the attribute means that there is no state represented.

The empty string can be a valid keyword.

2.4.3 Numbers

Status: First draft

2.4.3.1 Non-negative integers

A string is a valid non-negative integer if it consists of one or more characters in the range U+0030 DIGIT ZERO (0) to U+0039 DIGIT NINE (9).

A valid non-negative integer represents the number that is represented in base ten by that string of digits.

2.4.3.2 Signed integers

A string is a valid integer if it consists of one or more characters in the range U+0030 DIGIT ZERO (0) to U+0039 DIGIT NINE (9), optionally prefixed with a U+002D HYPHEN-MINUS ("-") character.

A valid integer without a U+002D HYPHEN-MINUS ("-") prefix represents the number that is represented in base ten by that string of digits. A valid integer with a U+002D HYPHEN-MINUS ("-") prefix represents the number represented in base ten by the string of digits that follows the U+002D HYPHEN-MINUS, subtracted from zero.

2.4.3.3 Real numbers

A string is a valid floating point number if it consists of:

  1. Optionally, a U+002D HYPHEN-MINUS ("-") character.
  2. A series of one or more characters in the range U+0030 DIGIT ZERO (0) to U+0039 DIGIT NINE (9).
  3. Optionally:
    1. A single U+002E FULL STOP (".") character.
    2. A series of one or more characters in the range U+0030 DIGIT ZERO (0) to U+0039 DIGIT NINE (9).
  4. Optionally:
    1. Either a U+0065 LATIN SMALL LETTER E character or a U+0045 LATIN CAPITAL LETTER E character.
    2. Optionally, a U+002D HYPHEN-MINUS ("-") character or U+002B PLUS SIGN ("+") character.
    3. A series of one or more characters in the range U+0030 DIGIT ZERO (0) to U+0039 DIGIT NINE (9).

A valid floating point number represents the number obtained by multiplying the significand by ten raised to the power of the exponent, where the significand is the first number, interpreted as base ten (including the decimal point and the number after the decimal point, if any, and interpreting the significand as a negative number if the whole string starts with a U+002D HYPHEN-MINUS ("-") character and the number is not zero), and where the exponent is the number after the E, if any (interpreted as a negative number if there is a U+002D HYPHEN-MINUS ("-") character between the E and the number and the number is not zero, or else ignoring a U+002B PLUS SIGN ("+") character between the E and the number if there is one). If there is no E, then the exponent is treated as zero.

The Infinity and Not-a-Number (NaN) values are not valid floating point numbers.

2.4.3.4 Ratios

The algorithms described in this section are used by the progress and meter elements.

A valid denominator punctuation character is one of the characters from the table below. There is a value associated with each denominator punctuation character, as shown in the table below.

Denominator Punctuation Character Value
U+0025 PERCENT SIGN % 100
U+066A ARABIC PERCENT SIGN Ùª 100
U+FE6A SMALL PERCENT SIGN ﹪ 100
U+FF05 FULLWIDTH PERCENT SIGN ï¼… 100
U+2030 PER MILLE SIGN ‰ 1000
U+2031 PER TEN THOUSAND SIGN ‱ 10000
2.4.3.5 Lists of integers

A valid list of integers is a number of valid integers separated by U+002C COMMA characters, with no other characters (e.g. no space characters). In addition, there might be restrictions on the number of integers that can be given, or on the range of values allowed.

2.4.4 Dates and times

In the algorithms below, the number of days in month month of year year is: 31 if month is 1, 3, 5, 7, 8, 10, or 12; 30 if month is 4, 6, 9, or 11; 29 if month is 2 and year is a number divisible by 400, or if year is a number divisible by 4 but not by 100; and 28 otherwise. This takes into account leap years in the Gregorian calendar. [GREGORIAN]

The digits in the date and time syntaxes defined in this section must be characters in the range U+0030 DIGIT ZERO to U+0039 DIGIT NINE, used to express numbers in base ten.

2.4.4.1 Months

A month consists of a specific proleptic Gregorian date with no time-zone information and no date information beyond a year and a month. [GREGORIAN]

A string is a valid month string representing a year year and month month if it consists of the following components in the given order:

  1. Four or more digits, representing year, where year > 0
  2. A U+002D HYPHEN-MINUS character (-)
  3. Two digits, representing the month month, in the range 1 â‰¤ month â‰¤ 12
2.4.4.2 Dates

A date consists of a specific proleptic Gregorian date with no time-zone information, consisting of a year, a month, and a day. [GREGORIAN]

A string is a valid date string representing a year year, month month, and day day if it consists of the following components in the given order:

  1. A valid month string, representing year and month
  2. A U+002D HYPHEN-MINUS character (-)
  3. Two digits, representing day, in the range 1 â‰¤ day â‰¤ maxday where maxday is the number of days in the month month and year year
2.4.4.3 Times

A time consists of a specific time with no time-zone information, consisting of an hour, a minute, a second, and a fraction of a second.

A string is a valid time string representing an hour hour, a minute minute, and a second second if it consists of the following components in the given order:

  1. Two digits, representing hour, in the range 0 â‰¤ hour â‰¤ 23
  2. A U+003A COLON character (:)
  3. Two digits, representing minute, in the range 0 â‰¤ minute â‰¤ 59
  4. Optionally (required if second is non-zero):
    1. A U+003A COLON character (:)
    2. Two digits, representing the integer part of second, in the range 0 â‰¤ s â‰¤ 59
    3. Optionally (required if second is not an integer):
      1. A 002E FULL STOP character (.)
      2. One or more digits, representing the fractional part of second

The second component cannot be 60 or 61; leap seconds cannot be represented.

2.4.4.4 Local dates and times

A local date and time consists of a specific proleptic Gregorian date, consisting of a year, a month, and a day, and a time, consisting of an hour, a minute, a second, and a fraction of a second, but expressed without a time zone. [GREGORIAN]

A string is a valid local date and time string representing a date and time if it consists of the following components in the given order:

  1. A valid date string representing the date.
  2. A U+0054 LATIN CAPITAL LETTER T character.
  3. A valid time string representing the time.
2.4.4.5 Global dates and times

A global date and time consists of a specific proleptic Gregorian date, consisting of a year, a month, and a day, and a time, consisting of an hour, a minute, a second, and a fraction of a second, expressed with a time zone, consisting of a number of hours and minutes. [GREGORIAN]

A string is a valid global date and time string representing a date, time, and a time-zone offset if it consists of the following components in the given order:

  1. A valid date string representing the date
  2. A U+0054 LATIN CAPITAL LETTER T character
  3. A valid time string representing the time
  4. Either:

This format allows for time zone offsets from -23:59 to +23:59. In practice, however, the range of actual time zones is -12:00 to +14:00, and the minutes component of actual time zones is always either 00, 30, or 45.

The following are some examples of dates written as valid global date and time strings.

"0037-12-13T00:00Z"
Midnight UTC on the birthday of Nero (the Roman Emperor).
"1979-10-14T12:00:00.001-04:00"
One millisecond after noon on October 14th 1979, in the time zone in use on the east coast of North America during daylight saving time.
"8592-01-01T02:09+02:09"
Midnight UTC on the 1st of January, 8592. The time zone associated with that time is two hours and nine minutes ahead of UTC, which is not a real time zone currently, but is nonetheless allowed.

Several things are notable about these dates:

2.4.4.6 Weeks

A week consists of a week-year number and a week number representing a seven day period. Each week-year in this calendaring system has either 52 weeks or 53 weeks, as defined below. A week is a seven-day period. The week starting on the Gregorian date Monday December 29th 1969 (1969-12-29) is defined as week number 1 in week-year 1970. Consecutive weeks are numbered sequentially. The week before the number 1 week in a week-year is the last week in the previous week-year, and vice versa. [GREGORIAN]

A week-year with a number year has 53 weeks if it corresponds to either a year year in the proleptic Gregorian calendar that has a Thursday as its first day (January 1st), or a year year in the proleptic Gregorian calendar that has a Wednesday as its first day (January 1st) and where year is a number divisible by 400, or a number divisible by 4 but not by 100. All other week-years have 52 weeks.

The week number of the last day of a week-year with 53 weeks is 53; the week number of the last day of a week-year with 52 weeks is 52.

The week-year number of a particular day can be different than the number of the year that contains that day in the proleptic Gregorian calendar. The first week in a week-year y is the week that contains the first Thursday of the Gregorian year y.

A string is a valid week string representing a week-year year and week week if it consists of the following components in the given order:

  1. Four or more digits, representing year, where year > 0
  2. A U+002D HYPHEN-MINUS character (-)
  3. A U+0057 LATIN CAPITAL LETTER W character
  4. Two digits, representing the week week, in the range 1 â‰¤ week â‰¤ maxweek, where maxweek is the week number of the last day of week-year year
2.4.4.7 Vaguer moments in time

A date or time string consists of either a date, a time, or a global date and time.

A string is a valid date or time string if it is also one of the following:

A string is a valid date or time string in content if it consists of zero or more White_Space characters, followed by a valid date or time string, followed by zero or more further White_Space characters.

2.4.5 Colors

Status: First draft

A simple color consists of three 8-bit numbers in the range 0..255, representing the red, green, and blue components of the color respectively, in the sRGB color space. [SRGB]

A string is a valid simple color if it is exactly seven characters long, and the first character is a U+0023 NUMBER SIGN (#) character, and the remaining six characters are all in the range U+0030 DIGIT ZERO (0) .. U+0039 DIGIT NINE (9), U+0041 LATIN CAPITAL LETTER A .. U+0046 LATIN CAPITAL LETTER F, U+0061 LATIN SMALL LETTER A .. U+0066 LATIN SMALL LETTER F, with the first two digits representing the red component, the middle two digits representing the green component, and the last two digits representing the blue component, in hexadecimal.

A string is a valid lowercase simple color if it is a valid simple color and doesn't use any characters in the range U+0041 LATIN CAPITAL LETTER A .. U+0046 LATIN CAPITAL LETTER F.


The 2D graphics context has a separate color syntax that also handles opacity.

2.4.6 Space-separated tokens

A set of space-separated tokens is a set of zero or more words separated by one or more space characters, where words consist of any string of one or more characters, none of which are space characters.

A string containing a set of space-separated tokens may have leading or trailing space characters.

An unordered set of unique space-separated tokens is a set of space-separated tokens where none of the words are duplicated.

An ordered set of unique space-separated tokens is a set of space-separated tokens where none of the words are duplicated but where the order of the tokens is meaningful.

Sets of space-separated tokens sometimes have a defined set of allowed values. When a set of allowed values is defined, the tokens must all be from that list of allowed values; other values are non-conforming. If no such set of allowed values is provided, then all values are conforming.

2.4.7 Comma-separated tokens

A set of comma-separated tokens is a set of zero or more tokens each separated from the next by a single U+002C COMMA character (,), where tokens consist of any string of zero or more characters, neither beginning nor ending with space characters, nor containing any U+002C COMMA characters (,), and optionally surrounded by space characters.

For instance, the string " a ,b,,d d " consists of four tokens: "a", "b", the empty string, and "d d". Leading and trailing whitespace around each token doesn't count as part of the token, and the empty string can be a token.

Sets of comma-separated tokens sometimes have further restrictions on what consists a valid token. When such restrictions are defined, the tokens must all fit within those restrictions; other values are non-conforming. If no such restrictions are specified, then all values are conforming.

2.4.8 Reversed DNS identifiers

A valid reversed DNS identifier is a string that consists of a series of IDNA labels in reverse order (i.e. starting with the top-level domain), the prefix of which, when reversed and converted to ASCII, corresponds to a registered domain.

For instance, the string "com.example.xn--74h" is a valid reversed DNS identifier because the string "example.com" is a registered domain.

2.4.9 References

A valid hash-name reference to an element of type type is a string consisting of a U+0023 NUMBER SIGN (#) character followed by a string which exactly matches the value of the name attribute of an element in the document with type type.

2.5 URLs

Status: Working draft

2.5.1 Terminology

Status: Working draft

A URL is a string used to identify a resource.

A URL is a valid URL if it is a valid Web address as defined by the Web addresses specification. [WEBADDRESSES]

A URL is an absolute URL if it is an absolute Web address as defined by the Web addresses specification. [WEBADDRESSES]

The term "URL" in this specification is used in a manner distinct from the precise technical meaning it is given in RFC 3986. Readers familiar with that RFC will find it easier to read this specification if they pretend the term "URL" as used herein is really called something else altogether. This is a willful violation of RFC 3986. [RFC3986]

2.5.2 Interfaces for URL manipulation

Status: Last call for comments

An interface that has a complement of URL decomposition attributes will have seven attributes with the following definitions:

           attribute DOMString protocol;
           attribute DOMString host;
           attribute DOMString hostname;
           attribute DOMString port;
           attribute DOMString pathname;
           attribute DOMString search;
           attribute DOMString hash;
o . protocol [ = value ]

Returns the current scheme of the underlying URL.

Can be set, to change the underlying URL's scheme.

o . host [ = value ]

Returns the current host and port (if it's not the default port) in the underlying URL.

Can be set, to change the underlying URL's host and port.

The host and the port are separated by a colon. The port part, if omitted, will be assumed to be the current scheme's default port.

o . hostname [ = value ]

Returns the current host in the underlying URL.

Can be set, to change the underlying URL's host.

o . port [ = value ]

Returns the current port in the underlying URL.

Can be set, to change the underlying URL's port.

o . pathname [ = value ]

Returns the current path in the underlying URL.

Can be set, to change the underlying URL's path.

o . search [ = value ]

Returns the current query component in the underlying URL.

Can be set, to change the underlying URL's query component.

o . hash [ = value ]

Returns the current fragment identifier in the underlying URL.

Can be set, to change the underlying URL's fragment identifier.

The table below demonstrates how the getter conditionsearch results in different results depending on the exact original syntax of the URL:

Input URL search value Explanation
http://example.com/ empty string No <query> component in input URL.
http://example.com/? ? There is a <query> component, but it is empty.
http://example.com/?test ?test The <query> component has the value "test".
http://example.com/?test# ?test The (empty) <fragment> component is not part of the <query> component.

2.6 Common DOM interfaces

Status: Working draft

2.6.1 Reflecting content attributes in DOM attributes

Some DOM attributes are defined to reflect a particular content attribute. This means that on getting, the DOM attribute returns the current value of the content attribute, and on setting, the DOM attribute changes the value of the content attribute to the given value.

A list of reflecting DOM attributes and their corresponding content attributes is given in the index.

2.6.2 Collections

Status: Working draft

The HTMLCollection, HTMLAllCollection, HTMLFormControlsCollection, HTMLOptionsCollection, and HTMLPropertyCollection interfaces represent various lists of DOM nodes. Collectively, objects implementing these interfaces are called collections.

When a collection is created, a filter and a root are associated with the collection.

For example, when the HTMLCollection object for the document.images attribute is created, it is associated with a filter that selects only img elements, and rooted at the root of the document.

The collection then represents a live view of the subtree rooted at the collection's root, containing only nodes that match the given filter. The view is linear.

2.6.2.1 HTMLCollection

The HTMLCollection interface represents a generic collection of elements.

interface HTMLCollection {
  readonly attribute unsigned long length;
  caller getter Element item(in unsigned long index);
  caller getter Element namedItem(in DOMString name);
  HTMLAllCollection tags(in DOMString tagName);
};
collection . length

Returns the number of elements in the collection.

element = collection . item(index)
collection[index]
collection(index)

Returns the item with index index from the collection. The items are sorted in tree order.

Returns null if index is out of range.

element = collection . namedItem(name)
collection[name]
collection(name)

Returns the first item with ID or name name from the collection.

Returns null if no element with that ID or name could be found.

Only a, applet, area, embed, form, frame, frameset, iframe, img, and object elements can have a name for the purpose of this method; their name is given by the value of their name attribute.

collection = collection . tags(tagName)

Returns a collection that is a filtered view of the current collection, containing only elements with the given tag name.

2.6.2.2 HTMLAllCollection

The HTMLAllCollection interface represents a generic collection of elements just like HTMLCollection, with the exception that its namedItem() method returns an HTMLCollection object when there are multiple matching elements.

interface HTMLAllCollection {
  readonly attribute unsigned long length;
  caller getter Element item(in unsigned long index);
  caller getter Object namedItem(in DOMString name);
  HTMLAllCollection tags(in DOMString tagName);
};
collection . length

Returns the number of elements in the collection.

element = collection . item(index)
collection[index]
collection(index)

Returns the item with index index from the collection. The items are sorted in tree order.

Returns null if index is out of range.

element = collection . namedItem(name)
collection = collection . namedItem(name)
collection[name]
collection(name)

Returns the item with ID or name name from the collection.

If there are multiple matching items, then an HTMLAllCollection object containing all those elements is returned.

Returns null if no element with that ID or name could be found.

Only a, applet, area, embed, form, frame, frameset, iframe, img, and object elements can have a name for the purpose of this method; their name is given by the value of their name attribute.

collection = collection . tags(tagName)

Returns a collection that is a filtered view of the current collection, containing only elements with the given tag name.

2.6.2.3 HTMLFormControlsCollection

The HTMLFormControlsCollection interface represents a collection of listed elements in form and fieldset elements.

interface HTMLFormControlsCollection {
  readonly attribute unsigned long length;
  caller getter HTMLElement item(in unsigned long index);
  caller getter Object namedItem(in DOMString name);
};

interface RadioNodeList : NodeList {
          attribute DOMString value;
};
collection . length

Returns the number of elements in the collection.

element = collection . item(index)
collection[index]
collection(index)

Returns the item with index index from the collection. The items are sorted in tree order.

Returns null if index is out of range.

element = collection . namedItem(name)
radioNodeList = collection . namedItem(name)
collection[name]
collection(name)

Returns the item with ID or name name from the collection.

If there are multiple matching items, then a RadioNodeList object containing all those elements is returned.

Returns null if no element with that ID or name could be found.

radioNodeList . value [ = value ]

Returns the value of the first checked radio button represented by the object.

Can be set, to check the first radio button with the given value represented by the object.

2.6.2.4 HTMLOptionsCollection

The HTMLOptionsCollection interface represents a list of option elements. It is always rooted on a select element and has attributes and methods that manipulate that element's descendants.

interface HTMLOptionsCollection {
           attribute unsigned long length;
  caller getter HTMLOptionElement item(in unsigned long index);
  caller getter Object namedItem(in DOMString name);
  void add(in HTMLElement element, optional in HTMLElement before);
  void add(in HTMLElement element, in long before);
  void remove(in long index);
};
collection . length [ = value ]

Returns the number of elements in the collection.

When set to a smaller number, truncates the number of option elements in the corresponding container.

When set to a greater number, adds new blank option elements to that container.

element = collection . item(index)
collection[index]
collection(index)

Returns the item with index index from the collection. The items are sorted in tree order.

Returns null if index is out of range.

element = collection . namedItem(name)
nodeList = collection . namedItem(name)
collection[name]
collection(name)

Returns the item with ID or name name from the collection.

If there are multiple matching items, then a NodeList object containing all those elements is returned.

Returns null if no element with that ID could be found.

collection . add(element [, before ] )

Inserts element before the node given by before.

The before argument can be a number, in which case element is inserted before the item with that number, or an element from the collection, in which case element is inserted before that element.

If before is omitted, null, or a number out of range, then element will be added at the end of the list.

This method will throw a HIERARCHY_REQUEST_ERR exception if element is an ancestor of the element into which it is to be inserted. If element is not an option or optgroup element, then the method does nothing.

2.6.2.5 HTMLPropertyCollection

The HTMLPropertyCollection interface represents a collection of elements that add name-value pairs to a particular item in the microdata model.

interface HTMLPropertyCollection {
  readonly attribute unsigned long length;
  readonly attribute DOMStringList names;
  caller getter HTMLElement item(in unsigned long index);
  caller getter PropertyNodeList namedItem(in DOMString name);
};

typedef sequence<any> PropertyValueArray;

interface PropertyNodeList : NodeList {
          attribute PropertyValueArray contents;
};
collection . length

Returns the number of elements in the collection.

collection . names

Returns a DOMStringList with the property names of the elements in the collection.

element = collection . item(index)
collection[index]
collection(index)

Returns the element with index index from the collection. The items are sorted in tree order.

Returns null if index is out of range.

propertyNodeList = collection . namedItem(name)
collection[name]
collection(name)

Returns a PropertyNodeList object containing any elements that add a property named name.

propertyNodeList . contents

Returns an array of the various values that the relevant elements have.

2.6.3 DOMTokenList

The DOMTokenList interface represents an interface to an underlying string that consists of a set of space-separated tokens.

DOMTokenList objects are always case-sensitive, even when the underlying string might ordinarily be treated in a case-insensitive manner.

interface DOMTokenList {
  readonly attribute unsigned long length;
  getter DOMString item(in unsigned long index);
  boolean contains(in DOMString token);
  void add(in DOMString token);
  void remove(in DOMString token);
  boolean toggle(in DOMString token);
  stringifier DOMString ();
};
tokenlist . length

Returns the number of tokens in the string.

element = tokenlist . item(index)
tokenlist[index]

Returns the token with index index. The tokens are returned in the order they are found in the underlying string.

Returns null if index is out of range.

hastoken = tokenlist . contains(token)

Returns true if the token is present; false otherwise.

Throws a SYNTAX_ERR exception if token is empty.

Throws an INVALID_CHARACTER_ERR exception if token contains any spaces.

tokenlist . add(token)

Adds token, unless it is already present.

Throws a SYNTAX_ERR exception if token is empty.

Throws an INVALID_CHARACTER_ERR exception if token contains any spaces.

tokenlist . remove(token)

Removes token if it is present.

Throws a SYNTAX_ERR exception if token is empty.

Throws an INVALID_CHARACTER_ERR exception if token contains any spaces.

hastoken = tokenlist . toggle(token)

Adds token if it is not present, or removes it if it is.

Throws a SYNTAX_ERR exception if token is empty.

Throws an INVALID_CHARACTER_ERR exception if token contains any spaces.

2.6.4 DOMSettableTokenList

The DOMSettableTokenList interface is the same as the DOMTokenList interface, except that it allows the underlying string to be directly changed.

interface DOMSettableTokenList : DOMTokenList {
            attribute DOMString value;
};
tokenlist . value

Returns the underlying string.

Can be set, to change the underlying string.

2.6.5 DOMStringMap

The DOMStringMap interface represents a set of name-value pairs. It exposes these using the scripting language's native mechanisms for property access.

The dataset attribute on elements exposes the data-* attributes on the element.

Given the following fragment and elements with similar constructions:

<img class="tower" id="tower5" data-x="12" data-y="5"
     data-ai="robotarget" data-hp="46" data-ability="flames"
     src="towers/rocket.png alt="Rocket Tower">

...one could imagine a function splashDamage() that takes some arguments, the first of which is the element to process:

function splashDamage(node, x, y, damage) {
  if (node.classList.contains('tower') && // checking the 'class' attribute
      node.dataset.x == x && // reading the 'data-x' attribute
      node.dataset.y == y) { // reading the 'data-y' attribute
    var hp = parseInt(node.dataset.hp); // reading the 'data-hp' attribute
    hp = hp - damage;
    if (hp < 0) {
      hp = 0;
      node.dataset.ai = 'dead'; // setting the 'data-ai' attribute
      delete node.dataset.ability; // removing the 'data-ability' attribute
    }
    node.dataset.hp = hp; // setting the 'data-hp' attribute
  }
}

2.6.6 DOM feature strings

DOM3 Core defines mechanisms for checking for interface support, and for obtaining implementations of interfaces, using feature strings. [DOMCORE]

Authors are strongly discouraged from using these, as they are notoriously unreliable and imprecise. Authors are encouraged to rely on explicit feature testing or the graceful degradation behavior intrinsic to some of the features in this specification.

2.6.7 Exceptions

The following DOMException codes are defined in DOM Core. [DOMCORE]

  1. INDEX_SIZE_ERR
  2. DOMSTRING_SIZE_ERR
  3. HIERARCHY_REQUEST_ERR
  4. WRONG_DOCUMENT_ERR
  5. INVALID_CHARACTER_ERR
  6. NO_DATA_ALLOWED_ERR
  7. NO_MODIFICATION_ALLOWED_ERR
  8. NOT_FOUND_ERR
  9. NOT_SUPPORTED_ERR
  10. INUSE_ATTRIBUTE_ERR
  11. INVALID_STATE_ERR
  12. SYNTAX_ERR
  13. INVALID_MODIFICATION_ERR
  14. NAMESPACE_ERR
  15. INVALID_ACCESS_ERR
  16. VALIDATION_ERR
  17. TYPE_MISMATCH_ERR
  18. SECURITY_ERR
  19. NETWORK_ERR
  20. ABORT_ERR
  21. URL_MISMATCH_ERR
  22. QUOTA_EXCEEDED_ERR
  23. PARSE_ERR
  24. SERIALIZE_ERR

3 Semantics, structure, and APIs of HTML documents

Status: Working draft

3.1 Introduction

This section is non-normative.

An introduction to marking up a document.

3.2 Documents

Every XML and HTML document in an HTML UA is represented by a Document object. [DOMCORE]

The document's address is an absolute URL that is set when the Document is created. The document's current address is an absolute URL that can change during the lifetime of the Document, for example when the user navigates to a fragment identifier on the page.

Interactive user agents typically expose the document's current address in their user interface.

When a Document is created by a script using the createDocument() API, the document's address is the same as the document's address of the active document of the script's browsing context.

Document objects are assumed to be XML documents unless they are flagged as being HTML documents when they are created. Whether a document is an HTML document or an XML document affects the behavior of certain APIs, as well as a few CSS rendering rules. [CSS]

A Document object created by the createDocument() API on the DOMImplementation object is initially an XML document, but can be made into an HTML document by calling document.open() on it.

3.2.1 Documents in the DOM

All Document objects (in user agents implementing this specification) also implement the HTMLDocument interface, available using binding-specific methods. (This is the case whether or not the document in question is an HTML document or indeed whether it contains any HTML elements at all.) Document objects also implement the document-level interface of any other namespaces found in the document that the UA supports.

For example, if an HTML implementation also supports SVG, then the Document object implements both HTMLDocument and SVGDocument.

Because the HTMLDocument interface is now obtained using binding-specific casting methods instead of simply being the primary interface of the document object, it is no longer defined as inheriting from Document.

[OverrideBuiltins]
interface HTMLDocument {
  // resource metadata management
  [PutForwards=href] readonly attribute Location location;
  readonly attribute DOMString URL;
           attribute DOMString domain;
  readonly attribute DOMString referrer;
           attribute DOMString cookie;
  readonly attribute DOMString lastModified;
  readonly attribute DOMString compatMode;
           attribute DOMString charset;
  readonly attribute DOMString characterSet;
  readonly attribute DOMString defaultCharset;
  readonly attribute DOMString readyState;

  // DOM tree accessors
           attribute DOMString title;
           attribute DOMString dir;
           attribute HTMLElement body;
  readonly attribute HTMLCollection images;
  readonly attribute HTMLCollection embeds;
  readonly attribute HTMLCollection plugins;
  readonly attribute HTMLCollection links;
  readonly attribute HTMLCollection forms;
  readonly attribute HTMLCollection scripts;
  NodeList getElementsByName(in DOMString elementName);
  NodeList getElementsByClassName(in DOMString classNames);
  NodeList getItems(optional in DOMString typeNames);
  getter any (in DOMString name);

  // dynamic markup insertion
           attribute DOMString innerHTML;
  HTMLDocument open(optional in DOMString type, optional in DOMString replace);
  WindowProxy open(in DOMString url, in DOMString name, in DOMString features, optional in boolean replace);
  void close();
  void write(in DOMString... text);
  void writeln(in DOMString... text);

  // user interaction
  Selection getSelection();
  readonly attribute Element activeElement;
  boolean hasFocus();
           attribute DOMString designMode;
  boolean execCommand(in DOMString commandId);
  boolean execCommand(in DOMString commandId, in boolean showUI);
  boolean execCommand(in DOMString commandId, in boolean showUI, in DOMString value);
  boolean queryCommandEnabled(in DOMString commandId);
  boolean queryCommandIndeterm(in DOMString commandId);
  boolean queryCommandState(in DOMString commandId);
  boolean queryCommandSupported(in DOMString commandId);
  DOMString queryCommandValue(in DOMString commandId);
  readonly attribute HTMLCollection commands;

  // event handler DOM attributes
           attribute Function onabort;
           attribute Function onblur;
           attribute Function oncanplay;
           attribute Function oncanplaythrough;
           attribute Function onchange;
           attribute Function onclick;
           attribute Function oncontextmenu;
           attribute Function ondblclick;
           attribute Function ondrag;
           attribute Function ondragend;
           attribute Function ondragenter;
           attribute Function ondragleave;
           attribute Function ondragover;
           attribute Function ondragstart;
           attribute Function ondrop;
           attribute Function ondurationchange;
           attribute Function onemptied;
           attribute Function onended;
           attribute Function onerror;
           attribute Function onfocus;
           attribute Function onformchange;
           attribute Function onforminput;
           attribute Function oninput;
           attribute Function oninvalid;
           attribute Function onkeydown;
           attribute Function onkeypress;
           attribute Function onkeyup;
           attribute Function onload;
           attribute Function onloadeddata;
           attribute Function onloadedmetadata;
           attribute Function onloadstart;
           attribute Function onmousedown;
           attribute Function onmousemove;
           attribute Function onmouseout;
           attribute Function onmouseover;
           attribute Function onmouseup;
           attribute Function onmousewheel;
           attribute Function onpause;
           attribute Function onplay;
           attribute Function onplaying;
           attribute Function onprogress;
           attribute Function onratechange;
           attribute Function onreadystatechange;
           attribute Function onscroll;
           attribute Function onseeked;
           attribute Function onseeking;
           attribute Function onselect;
           attribute Function onshow;
           attribute Function onstalled;
           attribute Function onsubmit;
           attribute Function onsuspend;
           attribute Function ontimeupdate;
           attribute Function onvolumechange;
           attribute Function onwaiting;
};
Document implements HTMLDocument;

Since the HTMLDocument interface holds methods and attributes related to a number of disparate features, the members of this interface are described in various different sections.

3.2.2 Security

User agents mustSECURITY_ERR exception whenever any of the members of an HTMLDocument object are accessed by scripts whose effective script origin is not the same as the Document's effective script origin.

3.2.3 Resource metadata management

Status: Last call for comments

document . URL

Returns the document's address.

document . referrer

Returns the address of the Document from which the user navigated to this one, unless it was blocked or there was no such document, in which case it returns the empty string.

The noreferrer link type can be used to block the referrer.

document . cookie [ = value ]

Returns the HTTP cookies that apply to the Document. If there are no cookies or cookies can't be applied to this resource, the empty string will be returned.

Can be set, to add a new cookie to the element's set of HTTP cookies.

If the Document has no browsing context an INVALID_STATE_ERR exception will be thrown. If the contents are sandboxed into a unique origin, a SECURITY_ERR exception will be thrown.

document . lastModified

Returns the date of the last modification to the document, as reported by the server, in the form "MM/DD/YYYY hh:mm:ss".

If the last modification date is not known, the current time is returned instead.

document . compatMode

In a conforming document, returns the string "CSS1Compat". (In quirks mode documents, returns the string "BackCompat", but a conforming document can never trigger quirks mode.)

document . charset [ = value ]

Returns the document's character encoding.

Can be set, to dynamically change the document's character encoding.

New values that are not IANA-registered aliases supported by the user agent are ignored.

document . characterSet

Returns the document's character encoding.

document . defaultCharset

Returns what might be the user agent's default character encoding.

document . readyState

Returns "loading" while the Document is loading, and "complete" once it has loaded.

The readystatechange event fires on the Document object when this value changes.

3.2.4 DOM tree accessors

The html element of a document is the document's root element, if there is one and it's an html element, or null otherwise.

The head element of a document is the first head element that is a child of the html element, if there is one, or null otherwise.


document . title [ = value ]

Returns the document's title, as given by the title element.

Can be set, to update the document's title. If there is no head element, the new value is ignored.

In SVG documents, the SVGDocument interface's title attribute takes precedence.

The title element of a document is the first title element in the document (in tree order), if there is one, or null otherwise.


document . body [ = value ]

Returns the body element.

Can be set, to replace the body element.

If the new value is not a body or frameset element, this will throw a HIERARCHY_REQUEST_ERR exception.

The body element of a document is the first child of the html element that is either a body element or a frameset element. If there is no such element, it is null.


document . images

Returns an HTMLCollection of the img elements in the Document.

document . embeds
document . plugins

Return an HTMLCollection of the embed elements in the Document.

document . links

Returns an HTMLCollection of the a and area elements in the Document that have href attributes.

document . forms

Return an HTMLCollection of the form elements in the Document.

document . scripts

Return an HTMLCollection of the script elements in the Document.

collection = document . getElementsByName(name)

Returns a NodeList of elements in the Document that have a name attribute with the value name.

collection = document . getElementsByClassName(classes)
collection = element . getElementsByClassName(classes)

Returns a NodeList of the elements in the object on which the method was invoked (a Document or an Element) that have all the classes given by classes.

The classes argument is interpreted as a space-separated list of classes.

HTML, SVG, and MathML elements define which classes they are in by having an attribute in the per-element partition with the name class containing a space-separated list of classes to which the element belongs. Other specifications may also allow elements in their namespaces to be labeled as being in specific classes.

Given the following XHTML fragment:

<div id="example">
 <p id="p1" class="aaa bbb"/>
 <p id="p2" class="aaa ccc"/>
 <p id="p3" class="bbb ccc"/>
</div>

A call to document.getElementById('example').getElementsByClassName('aaa') would return a NodeList with the two paragraphs p1 and p2 in it.

A call to getElementsByClassName('ccc bbb') would only return one node, however, namely p3. A call to document.getElementById('example').getElementsByClassName('bbb  ccc ') would return the same thing.

A call to getElementsByClassName('aaa,bbb') would return no nodes; none of the elements above are in the "aaa,bbb" class.


The dir attribute on the HTMLDocument interface is defined along with the dir content attribute.

3.3 Elements

3.3.1 Semantics

Elements, attributes, and attribute values in HTML are defined (by this specification) to have certain meanings (semantics). For example, the ol element represents an ordered list, and the lang attribute represents the language of the content.

Authors must not use elements, attributes, and attribute values for purposes other than their appropriate intended semantic purpose. Authors must not use elements, attributes, and attribute values that are not permitted by this specification or other applicable specifications.

For example, the following document is non-conforming, despite being syntactically correct:

<!DOCTYPE html>
<html lang="en-GB">
 <head> <title> Demonstration </title> </head>
 <body>
  <table>
   <tr> <td> My favourite animal is the cat. </td> </tr>
   <tr>
    <td>
     —<a href="http://example.org/~ernest/"><cite>Ernest</cite></a>,
     in an essay from 1992
    </td>
   </tr>
  </table>
 </body>
</html>

...because the data placed in the cells is clearly not tabular data (and the cite element mis-used). A corrected version of this document might be:

<!DOCTYPE html>
<html lang="en-GB">
 <head> <title> Demonstration </title> </head>
 <body>
  <blockquote>
   <p> My favourite animal is the cat. </p>
  </blockquote>
  <p>
   —<a href="http://example.org/~ernest/">Ernest</a>,
   in an essay from 1992
  </p>
 </body>
</html>

This next document fragment, intended to represent the heading of a corporate site, is similarly non-conforming because the second line is not intended to be a heading of a subsection, but merely a subheading or subtitle (a subordinate heading for the same section).

<body>
 <h1>ABC Company</h1>
 <h2>Leading the way in widget design since 1432</h2>
 ...

The hgroup element should be used in these kinds of situations:

<body>
 <hgroup>
  <h1>ABC Company</h1>
  <h2>Leading the way in widget design since 1432</h2>
 </hgroup>
 ...

In the next example, there is a non-conforming attribute value ("carpet") and a non-conforming attribute ("texture"), which is not permitted by this specification:

<label>Carpet: <input type="carpet" name="c" texture="deep pile"></label>

Here would be an alternative and correct way to mark this up:

<label>Carpet: <input type="text" class="carpet" name="c" data-texture="deep pile"></label>

Through scripting and using other mechanisms, the values of attributes, text, and indeed the entire structure of the document may change dynamically while a user agent is processing it. The semantics of a document at an instant in time are those represented by the state of the document at that instant in time, and the semantics of a document can therefore change over time. User agents must

HTML has a progress element that describes a progress bar. If its "value" attribute is dynamically updated by a script, the UA would update the rendering to show the progress changing.

3.3.2 Elements in the DOM

The nodes representing HTML elements in the DOM implement, and expose to scripts, the interfaces listed for them in the relevant sections of this specification. This includes HTML elements in XML documents, even when those documents are in another context (e.g. inside an XSLT transform).

Elements in the DOM represent things; that is, they have intrinsic meaning, also known as semantics.

For example, an ol element represents an ordered list.

The basic interface, from which all the HTML elements' interfaces inherit, is the HTMLElement interface.

interface HTMLElement : Element {
  // DOM tree accessors
  NodeList getElementsByClassName(in DOMString classNames);

  // dynamic markup insertion
           attribute DOMString innerHTML;
           attribute DOMString outerHTML;
  void insertAdjacentHTML(in DOMString position, in DOMString text);

  // metadata attributes
           attribute DOMString id;
           attribute DOMString title;
           attribute DOMString lang;
           attribute DOMString dir;
           attribute DOMString className;
  readonly attribute DOMTokenList classList;
  readonly attribute DOMStringMap dataset;

  // microdata
  [PutForwards=value] readonly attribute DOMSettableTokenList item;
  [PutForwards=value] readonly attribute DOMSettableTokenList itemprop;
  readonly attribute HTMLPropertyCollection properties;
           attribute DOMString content;
           attribute HTMLElement subject;

  // user interaction
           attribute boolean hidden;
  void click();
  void scrollIntoView();
  void scrollIntoView(in boolean top);
           attribute long tabIndex;
  void focus();
  void blur();
           attribute DOMString accessKey;
  readonly attribute DOMString accessKeyLabel;
           attribute boolean draggable;
           attribute DOMString contentEditable;
  readonly attribute boolean isContentEditable;
           attribute HTMLMenuElement contextMenu;
           attribute DOMString spellcheck;

  // command API
  readonly attribute DOMString commandType;
  readonly attribute DOMString label;
  readonly attribute DOMString icon;
  readonly attribute boolean disabled;
  readonly attribute boolean checked;

  // styling
  readonly attribute CSSStyleDeclaration style;

  // event handler DOM attributes
           attribute Function onabort;
           attribute Function onblur;
           attribute Function oncanplay;
           attribute Function oncanplaythrough;
           attribute Function onchange;
           attribute Function onclick;
           attribute Function oncontextmenu;
           attribute Function ondblclick;
           attribute Function ondrag;
           attribute Function ondragend;
           attribute Function ondragenter;
           attribute Function ondragleave;
           attribute Function ondragover;
           attribute Function ondragstart;
           attribute Function ondrop;
           attribute Function ondurationchange;
           attribute Function onemptied;
           attribute Function onended;
           attribute Function onerror;
           attribute Function onfocus;
           attribute Function onformchange;
           attribute Function onforminput;
           attribute Function oninput;
           attribute Function oninvalid;
           attribute Function onkeydown;
           attribute Function onkeypress;
           attribute Function onkeyup;
           attribute Function onload;
           attribute Function onloadeddata;
           attribute Function onloadedmetadata;
           attribute Function onloadstart;
           attribute Function onmousedown;
           attribute Function onmousemove;
           attribute Function onmouseout;
           attribute Function onmouseover;
           attribute Function onmouseup;
           attribute Function onmousewheel;
           attribute Function onpause;
           attribute Function onplay;
           attribute Function onplaying;
           attribute Function onprogress;
           attribute Function onratechange;
           attribute Function onreadystatechange;
           attribute Function onscroll;
           attribute Function onseeked;
           attribute Function onseeking;
           attribute Function onselect;
           attribute Function onshow;
           attribute Function onstalled;
           attribute Function onsubmit;
           attribute Function onsuspend;
           attribute Function ontimeupdate;
           attribute Function onvolumechange;
           attribute Function onwaiting;
};

interface HTMLUnknownElement : HTMLElement { };

The HTMLElement interface holds methods and attributes related to a number of disparate features, and the members of this interface are therefore described in various different sections of this specification.

3.3.3 Global attributes

The following attributes are common to and may be specified on all HTML elements:

In addition, unless otherwise specified, the following event handler content attributes may be specified on any HTML element:

The attributes marked with an asterisk have a different meaning when specified on body elements as those elements expose event handler attributes of the Window object with the same names.


Also, custom data attributes (e.g. data-foldername or data-msgid) can be specified on any HTML element, to store custom data specific to the page.

In HTML documents, elements in the HTML namespace may have an xmlns attribute specified, if, and only if, it has the exact value "http://www.w3.org/1999/xhtml". This does not apply to XML documents.

In HTML, the xmlns attribute has absolutely no effect. It is basically a talisman. It is allowed merely to make migration to and from XHTML mildly easier. When parsed by an HTML parser, the attribute ends up in no namespace, not the "http://www.w3.org/2000/xmlns/" namespace like namespace declaration attributes in XML do.

In XML, an xmlns attribute is part of the namespace declaration mechanism, and an element cannot actually have an xmlns attribute in no namespace specified.

3.3.3.1 The id attribute

Status: Implemented and widely deployed

The id attribute represents its element's unique identifier. The value must be unique in the element's home subtree and must contain at least one character. The value must not contain any space characters.

An element's unique identifier can be used for a variety of purposes, most notably as a way to link to specific parts of a document using fragment identifiers, as a way to target an element when scripting, and as a way to style a specific element from CSS.

3.3.3.2 The title attribute

Status: Implemented and widely deployed

The title attribute represents advisory information for the element, such as would be appropriate for a tooltip. On a link, this could be the title or a description of the target resource; on an image, it could be the image credit or a description of the image; on a paragraph, it could be a footnote or commentary on the text; on a citation, it could be further information about the source; and so forth. The value is text.

If this attribute is omitted from an element, then it implies that the title attribute of the nearest ancestor HTML element with a title attribute set is also relevant to this element. Setting the attribute overrides this, explicitly stating that the advisory information of any ancestors is not relevant to this element. Setting the attribute to the empty string indicates that the element has no advisory information.

If the title attribute's value contains U+000A LINE FEED (LF) characters, the content is split into multiple lines. Each U+000A LINE FEED (LF) character represents a line break.

Caution is advised with respect to the use of newlines in title attributes.

For instance, the following snippet actually defines an abbreviation's expansion with a line break in it:

<p>My logs show that there was some interest in <abbr title="Hypertext
Transport Protocol">HTTP</abbr> today.</p>

Some elements, such as link, abbr, and input, define additional semantics for the title attribute beyond the semantics described above.

3.3.3.3 The lang and xml:lang attributes

Status: Implemented and widely deployed

The lang attribute (in no namespace) specifies the primary language for the element's contents and for any of the element's attributes that contain text. Its value must be a valid BCP 47 language code, or the empty string. [BCP47]

The lang attribute in the XML namespace is defined in XML. [XML]

If these attributes are omitted from an element, then the language of this element is the same as the language of its parent element, if any. Setting the attribute to the empty string indicates that the primary language is unknown.

The lang attribute in no namespace may be used on any HTML element.

The lang attribute in the XML namespace may be used on HTML elements in XML documents, as well as elements in other namespaces if the relevant specifications allow it (in particular, MathML and SVG allow lang attributes in the XML namespace to be specified on their elements). If both the lang attribute in no namespace and the lang attribute in the XML namespace are specified on the same element, they must have exactly the same value when compared in an ASCII case-insensitive manner.

Authors must not use the lang attribute in the XML namespace in HTML documents. To ease migration to and from XHTML, authors may specify an attribute in no namespace with no prefix and with the literal localname "xml:lang" on HTML elements in HTML documents, but such attributes must only be specified if a lang attribute in no namespace is also specified, and both attributes must have the same value when compared in an ASCII case-insensitive manner.

3.3.3.4 The xml:base attribute (XML only)

The xml:base attribute is defined in XML Base. [XMLBASE]

The xml:base attribute may be used on elements of XML documents. Authors must not use the xml:base attribute in HTML documents.

3.3.3.5 The dir attribute

Status: Implemented and widely deployed

The dir attribute specifies the element's text directionality. The attribute is an enumerated attribute with the keyword ltr mapping to the state ltr, and the keyword rtl mapping to the state rtl. The attribute has no defaults.

The directionality of an element, which is used in particular by the canvas element's text rendering API, is either 'ltr' or 'rtl'. If the user agent supports CSS and the 'direction' property on this element has a computed value of either 'ltr' or 'rtl', then that is the directionality of the element. Otherwise, if the element is being rendered, then the directionality of the element is the directionality used by the presentation layer, potentially determined from the value of the dir attribute on the element. Otherwise, if the element's dir attribute has the state ltr, the element's directionality is 'ltr' (left-to-right); if the attribute has the state rtl, the element's directionality is 'rtl' (right-to-left); and otherwise, the element's directionality is the same as its parent element, or 'ltr' if there is no parent element.


document . dir [ = value ]

Returns the html element's dir attribute's value, if any.

Can be set, to either "ltr" or "rtl", to replace the html element's dir attribute's value.

If there is no html element, returns the empty string and ignores new values.

Authors are strongly encouraged to use the dir attribute to indicate text direction rather than using CSS, since that way their documents will continue to render correctly even in the absence of CSS (e.g. as interpreted by search engines).

3.3.3.6 The class attribute

Status: Last call for comments

Every HTML element may have a class attribute specified.

The attribute, if specified, must have a value that is an unordered set of unique space-separated tokens representing the various classes that the element belongs to.

Assigning classes to an element affects class matching in selectors in CSS, the getElementsByClassName() method in the DOM, and other such features.

Authors may use any value in the class attribute, but are encouraged to use the values that describe the nature of the content, rather than values that describe the desired presentation of the content.

3.3.3.7 The style attribute

Status: Implemented and widely deployed

All HTML elements may have the style content attribute set. If specified, the attribute must contain only a list of zero or more semicolon-separated (;) CSS declarations. [CSS]

Documents that use style attributes on any of their elements must still be comprehensible and usable if those attributes were removed.

In particular, using the style attribute to hide and show content, or to convey meaning that is otherwise not included in the document, is non-conforming. (To hide and show content, use the hidden attribute.)


element . style

Returns a CSSStyleDeclaration object for the element's style attribute.

In the following example, the words that refer to colors are marked up using the span element and the style attribute to make those words show up in the relevant colors in visual media.

<p>My sweat suit is <span style="color: green; background:
transparent">green</span> and my eyes are <span style="color: blue;
background: transparent">blue</span>.</p>
3.3.3.8 Embedding custom non-visible data

Status: Last call for comments

A custom data attribute is an attribute in no namespace whose name starts with the string "data-", has at least one character after the hyphen, is XML-compatible, and contains no characters in the range U+0041 .. U+005A (LATIN CAPITAL LETTER A .. LATIN CAPITAL LETTER Z).

All attributes in HTML documents get lowercased automatically, so the restriction on uppercase letters doesn't affect such documents.

Custom data attributes are intended to store custom data private to the page or application, for which there are no more appropriate attributes or elements.

These attributes are not intended for use by software that is independent of the site that uses the attributes.

For instance, a site about music could annotate list items representing tracks in an album with custom data attributes containing the length of each track. This information could then be used by the site itself to allow the user to sort the list by track length, or to filter the list for tracks of certain lengths.

<ol>
 <li data-length="2m11s">Beyond The Sea</li>
 ...
</ol>

It would be inappropriate, however, for the user to use generic software not associated with that music site to search for tracks of a certain length by looking at this data.

This is because these attributes are intended for use by the site's own scripts, and are not a generic extension mechanism for publicly-usable metadata.

Every HTML element may have any number of custom data attributes specified, with any value.


element . dataset

Returns a DOMStringMap object for the element's data-* attributes.

If a Web page wanted an element to represent a space ship, e.g. as part of a game, it would have to use the class attribute along with data-* attributes:

<div class="spaceship" data-id="92432"
     data-weapons="laser 2" data-shields="50%"
     data-x="30" data-y="10" data-z="90">
 <button class="fire"
         onclick="spaceships[this.parentNode.dataset.id].fire()">
  Fire
 </button>
</div>

Authors should carefully design such extensions so that when the attributes are ignored and any associated CSS dropped, the page is still usable.

3.3.4 Element definitions

Each element in this specification has a definition that includes the following information:

Categories
A list of categories to which the element belongs. These are used when defining the content models for each element.
Contexts in which this element may be used
A non-normative description of where the element can be used. This information is redundant with the content models of elements that allow this one as a child, and is provided only as a convenience.
Content model
A normative description of what content must be included as children and descendants of the element.
Content attributes
A normative list of attributes that may be specified on the element.
DOM interface
A normative definition of a DOM interface that such elements must implement.

This is then followed by a description of what the element represents, along with any additional normative conformance criteria that may apply to authors. Examples are sometimes also included.

3.3.5 Content models

All the elements in this specification have a defined content model, which describes what nodes are allowed inside the elements, and thus what the structure of an HTML document or fragment must look like.

As noted in the conformance and terminology sections, for the purposes of determining if an element matches its content model or not, CDATASection nodes in the DOM are treated as equivalent to Text nodes, and entity reference nodes are treated as if they were expanded in place.

The space characters are always allowed between elements. User agents represent these characters between elements in the source markup as text nodes in the DOM. Empty text nodes and text nodes consisting of just sequences of those characters are considered inter-element whitespace.

Inter-element whitespace, comment nodes, and processing instruction nodes must be ignored when establishing whether an element matches its content model or not, and must be ignored when following algorithms that define document and element semantics.

An element A is said to be preceded or followed by a second element B if A and B have the same parent node and there are no other element nodes or text nodes (other than inter-element whitespace) between them.

Authors must not use elements in the HTML namespace anywhere except where they are explicitly allowed, as defined for each element, or as explicitly required by other specifications. For XML compound documents, these contexts could be inside elements from other namespaces, if those elements are defined as providing the relevant contexts.

The Atom specification defines the Atom content element, when its type attribute has the value xhtml, as requiring that it contains a single HTML div element. Thus, a div element is allowed in that context, even though this is not explicitly normatively stated by this specification. [ATOM]

In addition, elements in the HTML namespace may be orphan nodes (i.e. without a parent node).

For example, creating a td element and storing it in a global variable in a script is conforming, even though td elements are otherwise only supposed to be used inside tr elements.

var data = {
  name: "Banana",
  cell: document.createElement('td'),
};
3.3.5.1 Kinds of content

Each element in HTML falls into zero or more categories that group elements with similar characteristics together. The following broad categories are used in this specification:

Some elements also fall into other categories, which are defined in other parts of this specification.

These categories are related as follows:

Sectioning content, heading content, phrasing content, and
  embedded content are all types of flow content. Embedded content is
  also a type of phrasing content.

In addition, certain elements are categorized as form-associated elements and further subcategorized to define their role in various form-related processing models.

Some elements have unique requirements and do not fit into any particular category.

3.3.5.1.1 Metadata content

Metadata content is content that sets up the presentation or behavior of the rest of the content, or that sets up the relationship of the document with other documents, or that conveys other "out of band" information.

Elements from other namespaces whose semantics are primarily metadata-related (e.g. RDF) are also metadata content.

Thus, in the XML serialization, one can use RDF, like this:

<html xmlns="http://www.w3.org/1999/xhtml"
      xmlns:r="http://www.w3.org/1999/02/22-rdf-syntax-ns#">
 <head>
  <title>Hedral's Home Page</title>
  <r:RDF>
   <Person xmlns="http://www.w3.org/2000/10/swap/pim/contact#"
           r:about="http://hedral.example.com/#">
    <fullName>Cat Hedral</fullName>
    <mailbox r:resource="mailto:hedral@damowmow.com"/>
    <personalTitle>Sir</personalTitle>
   </Person>
  </r:RDF>
 </head>
 <body>
  <h1>My home page</h1>
  <p>I like playing with string, I guess. Sister says squirrels are fun
  too so sometimes I follow her to play with them.</p>
 </body>
</html>

This isn't possible in the HTML serialization, however.

3.3.5.1.2 Flow content

Most elements that are used in the body of documents and applications are categorized as flow content.

As a general rule, elements whose content model allows any flow content should have either at least one descendant text node that is not inter-element whitespace, or at least one descendant element node that is embedded content. For the purposes of this requirement, del elements and their descendants must not be counted as contributing to the ancestors of the del element.

This requirement is not a hard requirement, however, as there are many cases where an element can be empty legitimately, for example when it is used as a placeholder which will later be filled in by a script, or when the element is part of a template and would on most pages be filled in but on some pages is not relevant.

3.3.5.1.3 Sectioning content

Sectioning content is content that defines the scope of headings and footers.

Each sectioning content element potentially has a heading and an outline. See the section on headings and sections for further details.

There are also certain elements that are sectioning roots. These are distinct from sectioning content, but they can also have an outline.

3.3.5.1.4 Heading content

Heading content defines the header of a section (whether explicitly marked up using sectioning content elements, or implied by the heading content itself).

3.3.5.1.5 Phrasing content

Phrasing content is the text of the document, as well as elements that mark up that text at the intra-paragraph level. Runs of phrasing content form paragraphs.

As a general rule, elements whose content model allows any phrasing content should have either at least one descendant text node that is not inter-element whitespace, or at least one descendant element node that is embedded content. For the purposes of this requirement, nodes that are descendants of del elements must not be counted as contributing to the ancestors of the del element.

Most elements that are categorized as phrasing content can only contain elements that are themselves categorized as phrasing content, not any flow content.

Text, in the context of content models, means text nodes. Text is sometimes used as a content model on its own, but is also phrasing content, and can be inter-element whitespace (if the text nodes are empty or contain just space characters).

3.3.5.1.6 Embedded content

Embedded content is content that imports another resource into the document, or content from another vocabulary that is inserted into the document.

Elements that are from namespaces other than the HTML namespace and that convey content but not metadata, are embedded content for the purposes of the content models defined in this specification. (For example, MathML, or SVG.)

Some embedded content elements can have fallback content: content that is to be used when the external resource cannot be used (e.g. because it is of an unsupported format). The element definitions state what the fallback is, if any.

3.3.5.1.7 Interactive content

Interactive content is content that is specifically intended for user interaction.

Certain elements in HTML have an activation behavior, which means that the user can activate them. This triggers a sequence of events dependent on the activation mechanism, and normally culminating in a click event followed by a DOMActivate event.

3.3.5.2 Transparent content models

Some elements are described as transparent; they have "transparent" in the description of their content model.

When a content model includes a part that is "transparent", those parts must not contain content that would not be conformant if all transparent elements in the tree were replaced, in their parent element, by the children in the "transparent" part of their content model, retaining order.

When a transparent element has no parent, then the part of its content model that is "transparent" must instead be treated as accepting any flow content.

3.3.5.3 Paragraphs

The term paragraph as defined in this section is distinct from (though related to) the p element defined later. The paragraph concept defined here is used to describe how to interpret documents.

A paragraph is typically a run of phrasing content that forms a block of text with one or more sentences that discuss a particular topic, as in typography, but can also be used for more general thematic grouping. For instance, an address is also a paragraph, as is a part of a form, a byline, or a stanza in a poem.

In the following example, there are two paragraphs in a section. There is also a heading, which contains phrasing content that is not a paragraph. Note how the comments and inter-element whitespace do not form paragraphs.

<section>
  <h1>Example of paragraphs</h1>
  This is the <em>first</em> paragraph in this example.
  <p>This is the second.</p>
  <!-- This is not a paragraph. -->
</section>

Paragraphs in flow content are defined relative to what the document looks like without the a, ins, del, and map elements complicating matters, since those elements, with their hybrid content models, can straddle paragraph boundaries, as shown in the first two examples below.

Generally, having elements straddle paragraph boundaries is best avoided. Maintaining such markup can be difficult.

The following example takes the markup from the earlier example and puts ins and del elements around some of the markup to show that the text was changed (though in this case, the changes admittedly don't make much sense). Notice how this example has exactly the same paragraphs as the previous one, despite the ins and del elements — the ins element straddles the heading and the first paragraph, and the del element straddles the boundary between the two paragraphs.

<section>
  <ins><h1>Example of paragraphs</h1>
  This is the <em>first</em> paragraph in</ins> this example<del>.
  <p>This is the second.</p></del>
  <!-- This is not a paragraph. -->
</section>

A paragraph is also formed explicitly by p elements.

The p element can be used to wrap individual paragraphs when there would otherwise not be any content other than phrasing content to separate the paragraphs from each other.

In the following example, the link spans half of the first paragraph, all of the heading separating the two paragraphs, and half of the second paragraph. It straddles the paragraphs and the heading.

<aside>
 Welcome!
 <a href="about.html">
  This is home of...
  <h1>The Falcons!</h1>
  The Lockheed Martin multirole jet fighter aircraft!
 </a>
 This page discusses the F-16 Fighting Falcon's innermost secrets.
</aside>

Here is another way of marking this up, this time showing the paragraphs explicitly, and splitting the one link element into three:

<aside>
 <p>Welcome! <a href="about.html">This is home of...</a></p>
 <h1><a href="about.html">The Falcons!</a></h1>
 <p><a href="about.html">The Lockheed Martin multirole jet
 fighter aircraft!</a> This page discusses the F-16 Fighting
 Falcon's innermost secrets.</p>
</aside>

It is possible for paragraphs to overlap when using certain elements that define fallback content. For example, in the following section:

<section>
 <h1>My Cats</h1>
 You can play with my cat simulator.
 <object data="cats.sim">
  To see the cat simulator, use one of the following links:
  <ul>
   <li><a href="cats.sim">Download simulator file</a>
   <li><a href="http://sims.example.com/watch?v=LYds5xY4INU">Use online simulator</a>
  </ul>
  Alternatively, upgrade to the Mellblom Browser.
 </object>
 I'm quite proud of it.
</section>

There are five paragraphs:

  1. The paragraph that says "You can play with my cat simulator. object I'm quite proud of it.", where object is the object element.
  2. The paragraph that says "To see the cat simulator, use one of the following links:".
  3. The paragraph that says "Download simulator file".
  4. The paragraph that says "Use online simulator".
  5. The paragraph that says "Alternatively, upgrade to the Mellblom Browser.".

The first paragraph is overlapped by the other four. A user agent that supports the "cats.sim" resource will only show the first one, but a user agent that shows the fallback will confusingly show the first sentence of the first paragraph as if it was in the same paragraph as the second one, and will show the last paragraph as if it was at the start of the second sentence of the first paragraph.

To avoid this confusion, explicit p elements can be used.

3.4 APIs in HTML documents

Status: Awaiting implementation feedback

For HTML documents, and for HTML elements in HTML documents, certain APIs defined in DOM Core become case-insensitive or case-changing, as sometimes defined in DOM Core, and as summarized below. [DOMCORE].

This does not apply to XML documents or to elements that are not in the HTML namespace despite being in HTML documents.

Element.tagName and Node.nodeName

These attributes mustconverted to ASCII uppercase, regardless of the case with which they were created.

Document.createElement()

The canonical form of HTML markup is all-lowercase; thus, this method will lowercase the argument before creating the requisite element. .

This doesn't apply to Document.createElementNS(). Thus, it is possible, by passing this last method a tag name in the wrong case, to create an element that claims to have the tag name of an element defined in this specification, but doesn't support its interfaces, because it really has another tag name not accessible from the DOM APIs.

Element.setAttribute()
Element.setAttributeNode()

Attribute names are converted to ASCII lowercase.

This doesn't apply to Document.setAttributeNS() and Document.setAttributeNodeNS().

Element.getAttribute()
Element.getAttributeNode()

Attribute names are converted to ASCII lowercase.

This doesn't apply to Document.getAttributeNS() and Document.getAttributeNodeNS().

Document.getElementsByTagName()
Element.getElementsByTagName()

HTML elements match by lower-casing the argument before comparison, elements from other namespaces are treated as in XML (case-sensitively).

Thus, in an HTML document with nodes in multiple namespaces, these methods will effectively be both case-sensitive and case-insensitive at the same time.

3.5 Dynamic markup insertion

APIs for dynamically inserting markup into the document interact with the parser, and thus their behavior, varies depending on whether they are used with HTML documents (and the HTML parser) or XHTML in XML documents (and the XML parser).

3.5.1 Controlling the input stream

Status: Last call for comments

The open() method comes in several variants with different numbers of arguments.

document = document . open( [ type [, replace ] ] )

Causes the Document to be replaced in-place, as if it was a new Document object, but reusing the previous object, which is then returned.

If the type argument is omitted or has the value "text/html", then the resulting Document has an HTML parser associated with it, which can be given data to parse using document.write(). Otherwise, all content passed to document.write() will be parsed as plain text.

If the replace argument is absent or false, a new entry is added to the session history to represent this entry, and the previous entries for this Document are all collapsed into one entry with a new Document object.

The method has no effect if the Document is still being parsed.

window = document . open( url, name, features [, replace ] )

Works like the window.open() method.

document . close()

Closes the input stream that was opened by the document.open() method.

3.5.2 document.write()

document . write(text...)

Adds the given string(s) to the Document's input stream. If necessary, calls the open() method implicitly first.

This method throws an INVALID_ACCESS_ERR exception when invoked on XML documents.

3.5.3 document.writeln()

document . writeln(text...)

Adds the given string(s) to the Document's input stream, followed by a newline character. If necessary, calls the open() method implicitly first.

This method throws an INVALID_ACCESS_ERR exception when invoked on XML documents.

3.5.4 innerHTML

Status: Implemented and widely deployed

The innerHTML DOM attribute represents the markup of the node's contents.

document . innerHTML [ = value ]

Returns a fragment of HTML or XML that represents the Document.

Can be set, to replace the Document's contents with the result of parsing the given string.

In the case of XML documents, will throw a SYNTAX_ERR if the Document cannot be serialized to XML, or if the given string is not well-formed.

element . innerHTML [ = value ]

Returns a fragment of HTML or XML that represents the element's contents.

Can be set, to replace the contents of the element with nodes parsed from the given string.

In the case of XML documents, will throw a SYNTAX_ERR if the element cannot be serialized to XML, or if the given string is not well-formed.

3.5.5 outerHTML

Status: Last call for comments

The outerHTML DOM attribute represents the markup of the element and its contents.

element . outerHTML [ = value ]

Returns a fragment of HTML or XML that represents the element and its contents.

Can be set, to replace the element with nodes parsed from the given string.

In the case of XML documents, will throw a SYNTAX_ERR if the element cannot be serialized to XML, or if the given string is not well-formed.

3.5.6 insertAdjacentHTML()

element . insertAdjacentHTML(position, text)

Parsed the given string text as HTML or XML and inserts the resulting nodes into the tree in the position given by the position argument, as follows:

"beforebegin"
Before the element itself.
"afterbegin"
Just inside the element, before its first child.
"beforeend"
Just inside the element, after its last child.
"afterend"
After the element itself.

Throws a SYNTAX_ERR exception the arguments have invalid values (e.g., in the case of XML documents, if the given string is not well-formed).

Throws a NO_MODIFICATION_ALLOWED_ERR exception if the given position isn't possible (e.g. inserting elements after the root element of a Document).

4 The elements of HTML

4.1 The root element

4.1.1 The html element

Status: Implemented and widely deployed

Categories
None.
Contexts in which this element may be used:
As the root element of a document.
Wherever a subdocument fragment is allowed in a compound document.
Content model:
A head element followed by a body element.
Content attributes:
Global attributes
manifest
DOM interface:
interface HTMLHtmlElement : HTMLElement {};

The html element represents the root of an HTML document.

The manifest attribute gives the address of the document's application cache manifest, if there is one. If the attribute is present, the attribute's value must be a valid URL.

The manifest attribute only has an effect during the early stages of document load. Changing the attribute dynamically thus has no effect (and thus, no DOM API is provided for this attribute).

For the purposes of application cache selection, later base elements cannot affect the resolving of relative URLs in manifest attributes, as the attributes are processed before those elements are seen.

4.2 Document metadata

4.2.1 The head element

Status: Implemented and widely deployed

Categories
None.
Contexts in which this element may be used:
As the first element in an html element.
Content model:
One or more elements of metadata content, of which exactly one is a title element.
Content attributes:
Global attributes
DOM interface:
interface HTMLHeadElement : HTMLElement {};

The head element represents a collection of metadata for the Document.

4.2.2 The title element

Status: Implemented and widely deployed

Categories
Metadata content.
Contexts in which this element may be used:
In a head element containing no other title elements.
Content model:
Text.
Content attributes:
Global attributes
DOM interface:
interface HTMLTitleElement : HTMLElement {
           attribute DOMString text;
};

The title element represents the document's title or name. Authors should use titles that identify their documents even when they are used out of context, for example in a user's history or bookmarks, or in search results. The document's title is often different from its first heading, since the first heading does not have to stand alone when taken out of context.

There must be no more than one title element per document.

The title element must not contain any elements.

The text DOM attribute must return the same value as the textContent DOM attribute on the element.

Here are some examples of appropriate titles, contrasted with the top-level headings that might be used on those same pages.

  <title>Introduction to The Mating Rituals of Bees</title>
    ...
  <h1>Introduction</h1>
  <p>This companion guide to the highly successful
  <cite>Introduction to Medieval Bee-Keeping</cite> book is...

The next page might be a part of the same site. Note how the title describes the subject matter unambiguously, while the first heading assumes the reader knows what the context is and therefore won't wonder if the dances are Salsa or Waltz:

  <title>Dances used during bee mating rituals</title>
    ...
  <h1>The Dances</h1>

The string to use as the document's title is given by the document.title DOM attribute.

4.2.3 The base element

Status: Working draft

Categories
Metadata content.
Contexts in which this element may be used:
In a head element containing no other base elements.
Content model:
Empty.
Content attributes:
Global attributes
href
target
DOM interface:
interface HTMLBaseElement : HTMLElement {
           attribute DOMString href;
           attribute DOMString target;
};

The base element allows authors to specify the document base URL for the purposes of resolving relative URLs, and the name of the default browsing context for the purposes of following hyperlinks. The element does not represent any content beyond this information.

There must be no more than one base element per document.

A base element must have either an href attribute, a target attribute, or both.

The href content attribute, if specified, must contain a valid URL.

A base element, if it has an href attribute, must come before any other elements in the tree that have attributes defined as taking URLs, except the html element (its manifest attribute isn't affected by base elements).

The target attribute, if specified, must contain a valid browsing context name or keyword, which specifies which browsing context is to be used as the default when hyperlinks and forms in the Document cause navigation.

A base element, if it has a target attribute, must come before any elements in the tree that represent hyperlinks.

Status: Last call for comments

Categories
Metadata content.
If the itemprop attribute is present: flow content.
If the itemprop attribute is present: phrasing content.
Contexts in which this element may be used:
Where metadata content is expected.
In a noscript element that is a child of a head element.
If the itemprop attribute is present: where phrasing content is expected.
Content model:
Empty.
Content attributes:
Global attributes
href
rel
media
hreflang
type
sizes
Also, the title attribute has special semantics on this element.
DOM interface:
interface HTMLLinkElement : HTMLElement {
           attribute boolean disabled;
           attribute DOMString href;
           attribute DOMString rel;
  readonly attribute DOMTokenList relList;
           attribute DOMString media;
           attribute DOMString hreflang;
           attribute DOMString type;
           attribute DOMString sizes;
};
HTMLLinkElement implements LinkStyle;

The link element allows authors to link their document to other resources.

The destination of the link(s) is given by the href attribute, which must be present and must contain a valid URL. If the href attribute is absent, then the element does not define a link.

The types of link indicated (the relationships) are given by the value of the rel attribute, which must be present, and must have a value that is a set of space-separated tokens. The allowed values and their meanings are defined in a later section. If the rel attribute is absent, or if the values used are not allowed according to the definitions in this specification, then the element does not define a link.

Two categories of links can be created using the link element. Links to external resources are links to resources that are to be used to augment the current document, and hyperlink links are links to other documents. The link types section defines whether a particular link type is an external resource or a hyperlink. One element can create multiple links (of which some might be external resource links and some might be hyperlinks); exactly which and how many links are created depends on the keywords given in the rel attribute. User agents must process the links on a per-link basis, not a per-element basis.

Each link is handled separately. For instance, if there are two link elements with rel="stylesheet", they each count as a separate external resource, and each is affected by its own attributes independently.

The exact behavior for links to external resources depends on the exact relationship, as defined for the relevant link type. Some of the attributes control whether or not the external resource is to be applied (as defined below).

Hyperlinks created with the link element and its rel attribute apply to the whole page. This contrasts with the rel attribute of a and area elements, which indicates the type of a link whose context is given by the link's location within the document.

The media attribute says which media the resource applies to. The value must be a valid media query. [MQ]

The default, if the media attribute is omitted, is all, meaning that by default links apply to all media.

The hreflang attribute on the link element has the same semantics as the hreflang attribute on hyperlink elements.

The type attribute gives the MIME type of the linked resource. It is purely advisory. The value must be a valid MIME type, optionally with parameters.

For external resource links, the type attribute is used as a hint to user agents so that they can avoid fetching resources they do not support.

The title attribute gives the title of the link. With one exception, it is purely advisory. The value is text. The exception is for style sheet links, where the title attribute defines alternative style sheet sets.

The title attribute on link elements differs from the global title attribute of most other elements in that a link without a title does not inherit the title of the parent element: it merely has no title.

The sizes attribute is used with the icon link type. The attribute must not be specified on link elements that do not have a rel attribute that specifies the icon keyword.

The DOM attribute disabled only applies to style sheet links. When the link element defines a style sheet link, then the disabled attribute behaves as defined for the alternative style sheets DOM. For all other link elements it always return false and does nothing on setting.

The LinkStyle interface is also be implemented by this element; the styling processing model defines how. [CSSOM]

4.2.5 The meta element

Status: Working draft

Categories
Metadata content.
If the itemprop attribute is present: flow content.
If the itemprop attribute is present: phrasing content.
Contexts in which this element may be used:
If the charset attribute is present, or if the element's http-equiv attribute is in the Encoding declaration state: in a head element.
If the http-equiv attribute is present and in the Encoding declaration state: in a head element.
If the http-equiv attribute is present but not in the Encoding declaration state: in a noscript element that is a child of a head element.
If the name attribute is present: where metadata content is expected.
If the itemprop attribute is present: where phrasing content is expected.
Content model:
Empty.
Content attributes:
Global attributes
name
http-equiv
content
charset
DOM interface:
interface HTMLMetaElement : HTMLElement {
           attribute DOMString name;
           attribute DOMString httpEquiv;
};

The meta element represents various kinds of metadata that cannot be expressed using the title, base, link, style, and script elements.

The meta element can represent document-level metadata with the name attribute, pragma directives with the http-equiv attribute, and the file's character encoding declaration when an HTML document is serialized to string form (e.g. for transmission over the network or for disk storage) with the charset attribute.

Exactly one of the name, http-equiv, charset, and itemprop attributes must be specified.

If either name, http-equiv, or itemprop is specified, then the content attribute must also be specified. Otherwise, it must be omitted.

The charset attribute specifies the character encoding used by the document. This is a character encoding declaration. If the attribute is present in an XML document, its value must be an ASCII case-insensitive match for the string "UTF-8" (and the document is therefore required to use UTF-8 as its encoding).

The charset attribute on the meta element has no effect in XML documents, and is only allowed in order to facilitate migration to and from XHTML.

There must not be more than one meta element with a charset attribute per document.

The content attribute gives the value of the document metadata or pragma directive when the element is used for those purposes. The allowed values depend on the exact context, as described in subsequent sections of this specification.

If a meta element has a name attribute, it sets document metadata. Document metadata is expressed in terms of name/value pairs, the name attribute on the meta element giving the name, and the content attribute on the same element giving the value. The name specifies what aspect of metadata is being set; valid names and the meaning of their values are described in the following sections. If a meta element has no content attribute, then the value part of the metadata name/value pair is the empty string.

4.2.5.1 Standard metadata names

This specification defines a few names for the name attribute of the meta element.

application-name

The value must be a short free-form string that giving the name of the Web application that the page represents. If the page is not a Web application, the application-name metadata name must not be used.

description

The value must be a free-form string that describes the page. The value must be appropriate for use in a directory of pages, e.g. in a search engine.

generator

The value must be a free-form string that identifies the software used to generate the document. This value must not be used on hand-authored pages.

4.2.5.2 Other metadata names

Extensions to the predefined set of metadata names may be registered in the WHATWG Wiki MetaExtensions page.

Anyone is free to edit the WHATWG Wiki MetaExtensions page at any time to add a type. These new names must be specified with the following information:

Keyword

The actual name being defined. The name should not be confusingly similar to any other defined name (e.g. differing only in case).

Brief description

A short description of what the metadata name's meaning is, including the format the value is required to be in.

Link to more details
A link to a more detailed description of the metadata name's semantics and requirements. It could be another page on the Wiki, or a link to an external page.
Synonyms

A list of other names that have exactly the same processing requirements. Authors should not use the names defined to be synonyms, they are only intended to allow user agents to support legacy content.

Status

One of the following:

Proposal
The name has not received wide peer review and approval. Someone has proposed it and is using it.
Accepted
The name has received wide peer review and approval. It has a specification that unambiguously defines how to handle pages that use the name, including when they use it in incorrect ways.
Unendorsed
The metadata name has received wide peer review and it has been found wanting. Existing pages are using this keyword, but new pages should avoid it. The "brief description" and "link to more details" entries will give details of what authors should use instead, if anything.

If a metadata name is added with the "proposal" status and found to be redundant with existing values, it should be removed and listed as a synonym for the existing value.

This specification does not define how new values will get approved. It is expected that the Wiki will have a community that addresses this.

Metadata names whose values are to be URLs must not be proposed or accepted. Links must be represented using the link element, not the meta element.

4.2.5.3 Pragma directives

When the http-equiv attribute is specified on a meta element, the element is a pragma directive.

The http-equiv attribute is an enumerated attribute. The following table lists the keywords defined for this attribute. The states given in the first cell of the rows with keywords give the states to which those keywords map.

State Keywords Notes
Content Language content-language Conformance checkers will include a warning
Encoding declaration content-type
Default style default-style
Refresh refresh
Content language state (http-equiv="content-language")

This pragma sets the document-wide default language. Until the pragma is successfully processed, there is no document-wide default language.

Conformance checkers will include a warning if this pragma is used. Authors are encouraged to use the lang attribute instead.

For meta elements with an http-equiv attribute in the Content Language state, the content attribute must have a value consisting of a valid BCP 47 language code. [BCP47]

This pragma is not exactly equivalent to the HTTP Content-Language header, for instance it only supports one language. [HTTP]

Encoding declaration state (http-equiv="content-type")

The Encoding declaration state is just an alternative form of setting the charset attribute: it is a character encoding declaration.

For meta elements with an http-equiv attribute in the Encoding declaration state, the content attribute must have a value that is an ASCII case-insensitive match for a string that consists of: the literal string "text/html;", optionally followed by any number of space characters, followed by the literal string "charset=", followed by the character encoding name of the character encoding declaration.

If the document contains a meta element with an http-equiv attribute in the Encoding declaration state, then the document must not contain a meta element with the charset attribute present.

The Encoding declaration state may be used in HTML documents, but elements with an http-equiv attribute in that state must not be used in XML documents.

Default style state (http-equiv="default-style")

This pragma sets the name of the default alternative style sheet set.

Refresh state (http-equiv="refresh")

This pragma acts as timed redirect.

For meta elements with an http-equiv attribute in the Refresh state, the content attribute must have a value consisting either of:

In the former case, the integer represents a number of seconds before the page is to be reloaded; in the latter case the integer represents a number of seconds before the page is to be replaced by the page at the given URL.

There must not be more than one meta element with any particular state in the document at a time.

4.2.5.4 Other pragma directives

Extensions to the predefined set of pragma directives may, under certain conditions, be registered in the WHATWG Wiki PragmaExtensions page.

Such extensions must use a name that is identical to a previously-registered HTTP header defined in an RFC, and must have behavior identical to that described for the HTTP header. Pragma directions corresponding to headers describing metadata, or not requiring specific user agent processing, must not be registered; instead, use metadata names. Pragma directions corresponding to headers that affect the HTTP processing model (e.g. caching) must not be registered, as they would result in HTTP-level behavior being different for user agents that implement HTML than for user agents that do not.

Anyone is free to edit the WHATWG Wiki PragmaExtensions page at any time to add a pragma directive satisfying these conditions. Such registrations must specify the following information:

Keyword

The actual name being defined.

Brief description

A short description of the purpose of the pragma directive.

Specification
A link to an IETF RFC defining the corresponding HTTP header.
4.2.5.5 Specifying the document's character encoding

A character encoding declaration is a mechanism by which the character encoding used to store or transmit a document is specified.

The following restrictions apply to character encoding declarations:

If an HTML document does not start with a BOM, and if its encoding is not explicitly given by Content-Type metadata, then the character encoding used must be an ASCII-compatible character encoding, and, in addition, if that encoding isn't US-ASCII itself, then the encoding must be specified using a meta element with a charset attribute or a meta element with an http-equiv attribute in the Encoding declaration state.

If an HTML document contains a meta element with a charset attribute or a meta element with an http-equiv attribute in the Encoding declaration state, then the character encoding used must be an ASCII-compatible character encoding.

Authors should not use JIS-X-0208 (JIS_C6226-1983), JIS-X-0212 (JIS_X0212-1990), encodings based on ISO-2022, and encodings based on EBCDIC. Authors should not use UTF-32. Authors must not use the CESU-8, UTF-7, BOCU-1 and SCSU encodings. [RFC1345] [RFC1468] [RFC2237] [RFC1554] [RFC1922] [RFC1557] [UNICODE] [CESU8] [UTF7] [BOCU1] [SCSU]

Authors are encouraged to use UTF-8. Conformance checkers may advise against authors using legacy encodings.

Using non-UTF-8 encodings can have unexpected results on form submission and URL encodings, which use the document's character encoding by default.

In XHTML, the XML declaration should be used for inline character encoding information, if necessary.

4.2.6 The style element

Status: Working draft

Categories
Metadata content.
If the scoped attribute is present: flow content.
Contexts in which this element may be used:
If the scoped attribute is absent: where metadata content is expected.
If the scoped attribute is absent: in a noscript element that is a child of a head element.
If the scoped attribute is present: where flow content is expected, but before any other flow content other than other style elements and inter-element whitespace.
Content model:
Depends on the value of the type attribute.
Content attributes:
Global attributes
media
type
scoped
Also, the title attribute has special semantics on this element.
DOM interface:
interface HTMLStyleElement : HTMLElement {
           attribute boolean disabled;
           attribute DOMString media;
           attribute DOMString type;
           attribute boolean scoped;
};
HTMLStyleElement implements LinkStyle;

The style element allows authors to embed style information in their documents. The style element is one of several inputs to the styling processing model. The element does not represent content for the user.

If the type attribute is given, it must contain a valid MIME type, optionally with parameters, that designates a styling language. If the attribute is absent, the type defaults to text/css. [RFC2318]

The media attribute says which media the styles apply to. The value must be a valid media query. [MQ]

The default, if the media attribute is omitted, is all, meaning that by default styles apply to all media.

Status: First draft

The scoped attribute is a boolean attribute. If set, it indicates that the styles are intended just for the subtree rooted at the style element's parent element, as opposed to the whole Document.

The title attribute on style elements defines alternative style sheet sets. If the style element has no title attribute, then it has no title; the title attribute of ancestors does not apply to the style element. [CSSOM]

The title attribute on style elements, like the title attribute on link elements, differs from the global title attribute in that a style block without a title does not inherit the title of the parent element: it merely has no title.

This specification does not specify a style system, but CSS is expected to be supported by most Web browsers. [CSS]

The DOM disabled attribute behaves as defined for the alternative style sheets DOM.

The LinkStyle interface is also be implemented by this element; the styling processing model defines how. [CSSOM]

4.2.7 Styling

Status: Working draft

The link and style elements can provide styling information for the user agent to use when rendering the document. The DOM Styling specification specifies what styling information is to be used by the user agent and how it is to be used. [CSSOM]

The style and link elements implement the LinkStyle interface. [CSSOM]

4.3 Scripting

Scripts allow authors to add interactivity to their documents.

Authors are encouraged to use declarative alternatives to scripting where possible, as declarative mechanisms are often more maintainable, and many users disable scripting.

For example, instead of using script to show or hide a section to show more details, the details element could be used.

Authors are also encouraged to make their applications degrade gracefully in the absence of scripting support.

For example, if an author provides a link in a table header to dynamically resort the table, the link could also be made to function without scripts by requesting the sorted table from the server.

4.3.1 The script element

Status: Working draft

Categories
Metadata content.
Flow content.
Phrasing content.
Contexts in which this element may be used:
Where metadata content is expected.
Where phrasing content is expected.
Content model:
If there is no src attribute, depends on the value of the type attribute.
If there is a src attribute, the element must be either empty or contain only script documentation.
Content attributes:
Global attributes
src
async
defer
type
charset
DOM interface:
interface HTMLScriptElement : HTMLElement {
           attribute DOMString src;
           attribute boolean async;
           attribute boolean defer;
           attribute DOMString type;
           attribute DOMString charset;
           attribute DOMString text;
};

The script element allows authors to include dynamic script and data blocks in their documents. The element does not represent content for the user.

When used to include dynamic scripts, the scripts may either be embedded inline or may be imported from an external file using the src attribute. If the language is not that described by "text/javascript", then the type attribute must be present. If the type attribute is present, its value must be the type of the script's language.

When used to include data blocks, the data must be embedded inline, the format of the data must be given using the type attribute, and the src attribute must not be specified.

The type attribute gives the language of the script or format of the data. If the attribute is present, its value must be a valid MIME type, optionally with parameters. The charset parameter must not be specified. (The default, which is used if the attribute is absent, is "text/javascript".)

The src attribute, if specified, gives the address of the external script resource to use. The value of the attribute must be a valid URL identifying a script resource of the type given by the type attribute, if the attribute is present, or of the type "text/javascript", if the attribute is absent.

The charset attribute gives the character encoding of the external script resource. The attribute must not be specified if the src attribute is not present. If the attribute is set, its value must be a valid character encoding name, must be the preferred name for that encoding, and must match the encoding given in the charset parameter of the Content-Type metadata of the external file, if any. [IANACHARSET]

The async and defer attributes are boolean attributes that indicate how the script should be executed.

There are three possible modes that can be selected using these attributes. If the async attribute is present, then the script will be executed asynchronously, as soon as it is available. If the async attribute is not present but the defer attribute is present, then the script is executed when the page has finished parsing. If neither attribute is present, then the script is fetched and executed immediately, before the user agent continues parsing the page. The exact processing details for these attributes is described below.

The defer attribute may be specified even if the async attribute is specified, to cause legacy Web browsers that only support defer (and not async) to fall back to the defer behavior instead of the synchronous blocking behavior that is the default.

If the defer attribute may be specified, the src attribute must also be specified.

Changing the src, type, charset, async, and defer attributes dynamically has no direct effect; these attribute are only used at specific times described below (namely, when the element is inserted into the document).

script . text [ = value ]

Returns the contents of the element, ignoring child nodes that aren't text nodes.

Can be set, to replace the element's children with the given value.

In this example, two script elements are used. One embeds an external script, and the other includes some data.

<script src="game-engine.js"></script>
<script type="text/x-game-map">
........U.........e
o............A....e
.....A.....AAA....e
.A..AAA...AAAAA...e
</script>

The data in this case might be used by the script to generate the map of a video game. The data doesn't have to be used that way, though; maybe the map data is actually embedded in other parts of the page's markup, and the data block here is just used by the site's search engine to help users who are looking for particular features in their game maps.

When inserted using the document.write() method, script elements execute (typically synchronously), but when inserted using innerHTML and outerHTML attributes, they do not execute at all.

4.3.1.1 Scripting languages

The following lists some MIME types and the languages to which they refer:

application/ecmascript
application/javascript
application/x-ecmascript
application/x-javascript
text/ecmascript
text/javascript
text/javascript1.0
text/javascript1.1
text/javascript1.2
text/javascript1.3
text/javascript1.4
text/javascript1.5
text/jscript
text/livescript
text/x-ecmascript
text/x-javascript
JavaScript. [ECMA262]
text/javascript;e4x=1
JavaScript with ECMAScript for XML. [ECMA357]
4.3.1.2 Inline documentation for external scripts

If a script element's src attribute is specified, then the contents of the script element, if any, must be such that the value of the DOM text attribute, which is derived from the element's contents, matches the documentation production in the following ABNF, the character set for which is Unicode. [ABNF]

documentation = *( *( space / tab / comment ) [ line-comment ] newline )
comment       = slash star *( not-star / star not-slash ) 1*star slash
line-comment  = slash slash *not-newline

; characters
tab           = %x0009 ; U+0009 TAB
newline       = %x000A ; U+000A LINE FEED
space         = %x0020 ; U+0020 SPACE
star          = %x002A ; U+002A ASTERISK
slash         = %x002F ; U+002F SOLIDUS
not-newline   = %x0000-0009 / %x000B-10FFFF
                ; a Unicode character other than U+000A LINE FEED
not-star      = %x0000-0029 / %x002B-10FFFF
                ; a Unicode character other than U+002A ASTERISK
not-slash     = %x0000-002E / %x0030-10FFFF
                ; a Unicode character other than U+002F SOLIDUS

This allows authors to include documentation, such as license information or API information, inside their documents while still referring to external script files. The syntax is constrained so that authors don't accidentally include what looks like valid script while also providing a src attribute.

<script src="cool-effects.js">
 // create new instances using:
 //    var e = new Effect();
 // start the effect using .play, stop using .stop:
 //    e.play();
 //    e.stop();
</script>

4.3.2 The noscript element

Status: Implemented and widely deployed

Categories
Metadata content.
Flow content.
Phrasing content.
Contexts in which this element may be used:
In a head element of an HTML document, if there are no ancestor noscript elements.
Where phrasing content is expected in HTML documents, if there are no ancestor noscript elements.
Content model:
When scripting is disabled, in a head element: in any order, zero or more link elements, zero or more style elements, and zero or more meta elements.
When scripting is disabled, not in a head element: transparent, but there must be no noscript element descendants.
Otherwise: text that conforms to the requirements given in the prose.
Content attributes:
Global attributes
DOM interface:
Uses HTMLElement.

The noscript element represents nothing if scripting is enabled, and represents its children if scripting is disabled. It is used to present different markup to user agents that support scripting and those that don't support scripting, by affecting how the document is parsed.

When used in HTML documents, the allowed content model is as follows:

In a head element, if scripting is disabled for the noscript element

The noscript element must contain only link, style, and meta elements.

In a head element, if scripting is enabled for the noscript element

The noscript element must contain only text, except that invoking the HTML fragment parsing algorithm with the noscript element as the context element and the text contents as the input must result in a list of nodes that consists only of link, style, and meta elements, and no parse errors.

Outside of head elements, if scripting is disabled for the noscript element

The noscript element's content model is transparent, with the additional restriction that a noscript element must not have a noscript element as an ancestor (that is, noscript can't be nested).

Outside of head elements, if scripting is enabled for the noscript element

The noscript element must contain only text, except that the text must be such that running the following algorithm results in a conforming document with no noscript elements and no script elements, and such that no step in the algorithm causes an HTML parser to flag a parse error:

  1. Remove every script element from the document.
  2. Make a list of every noscript element in the document. For every noscript element in that list, perform the following steps:
    1. Let the parent element be the parent element of the noscript element.
    2. Take all the children of the parent element that come before the noscript element, and call these elements the before children.
    3. Take all the children of the parent element that come after the noscript element, and call these elements the after children.
    4. Let s be the concatenation of all the text node children of the noscript element.
    5. Set the innerHTML attribute of the parent element to the value of s. (This, as a side-effect, causes the noscript element to be removed from the document.)
    6. Insert the before children at the start of the parent element, preserving their original relative order.
    7. Insert the after children at the end of the parent element, preserving their original relative order.

All these contortions are required because, for historical reasons, the noscript element is handled differently by the HTML parser based on whether scripting was enabled or not when the parser was invoked. The element is not allowed in XML, because in XML the parser is not affected by such state, and thus the element would not have the desired effect.

The noscript element must not be used in XML documents.

The noscript element is only effective in the the HTML syntax, it has no effect in the the XHTML syntax.

4.4 Sections

4.4.1 The body element

Status: Implemented and widely deployed

Categories
Sectioning root.
Contexts in which this element may be used:
As the second element in an html element.
Content model:
Flow content.
Content attributes:
Global attributes
onafterprint
onbeforeprint
onbeforeunload
onblur
onerror
onfocus
onhashchange
onload
onmessage
onoffline
ononline
onpopstate
onredo
onresize
onstorage
onundo
onunload
DOM interface:
interface HTMLBodyElement : HTMLElement {
           attribute Function onafterprint;
           attribute Function onbeforeprint;
           attribute Function onbeforeunload;
           attribute Function onblur;
           attribute Function onerror;
           attribute Function onfocus;
           attribute Function onhashchange;
           attribute Function onload;
           attribute Function onmessage;
           attribute Function onoffline;
           attribute Function ononline;
           attribute Function onpopstate;
           attribute Function onredo;
           attribute Function onresize;
           attribute Function onstorage;
           attribute Function onundo;
           attribute Function onunload;
};

The body element represents the main content of the document.

In conforming documents, there is only one body element. The document.body DOM attribute provides scripts with easy access to a document's body element.

The body element exposes as event handler content attributes a number of the event handler attributes of the Window object. It also mirrors their event handler DOM attributes.

The onblur, onerror, onfocus, and onload event handler attributes of the Window object, exposed on the body element, shadow the generic event handler attributes with the same names normally supported by HTML elements.

Thus, for example, a bubbling error event fired on a child of the body element of a Document would first trigger the onerror event handler content attributes of that element, then that of the root html element, and only then would it trigger the onerror event handler content attribute on the body element. This is because the event would bubble from the target, to the body, to the html, to the Document, to the Window, and the event handler attribute on the body is watching the Window not the body. A regular event listener attached to the body using addEventListener(), however, would fire when the event bubbled through the body and not when it reaches the Window object.

4.4.2 The section element

Status: Last call for comments

Categories
Flow content.
Sectioning content.
formatBlock candidate.
Contexts in which this element may be used:
Where flow content is expected.
Content model:
Flow content.
Content attributes:
Global attributes
cite
DOM interface:
interface HTMLSectionElement : HTMLElement {
           attribute DOMString cite;
};

The section element represents a generic document or application section. A section, in this context, is a thematic grouping of content, typically with a heading, possibly with a footer.

Examples of sections would be chapters, the various tabbed pages in a tabbed dialog box, or the numbered sections of a thesis. A Web site's home page could be split into sections for an introduction, news items, contact information.

The cite attribute may be used if the content of the section was taken from another page (e.g. syndicating content from multiple sources on one page). The attribute, if present, must contain a valid URL referencing the original source.

The section element is not a generic container element. When an element is needed for styling purposes or as a convenience for scripting, authors are encouraged to use the div element instead. A general rule is that the section element is appropriate only if the element's contents would be listed explicitly in the document's outline.

In the following example, we see an article (part of a larger Web page) about apples, containing two short sections.

<article>
 <hgroup>
  <h1>Apples</h1>
  <h2>Tasty, delicious fruit!</h2>
 </hgroup>
 <p>The apple is the pomaceous fruit of the apple tree.</p>
 <section>
  <h1>Red Delicious</h1>
  <p>These bright red apples are the most common found in many
  supermarkets.</p>
 </section>
 <section>
  <h1>Granny Smith</h1>
  <p>These juicy, green apples make a great filling for
  apple pies.</p>
 </section>
</article>

Notice how the use of section means that the author can use h1 elements throughout, without having to worry about whether a particular section is at the top level, the second level, the third level, and so on.

4.4.3 The nav element

Status: Last call for comments

Categories
Flow content.
Sectioning content.
formatBlock candidate.
Contexts in which this element may be used:
Where flow content is expected.
Content model:
Flow content.
Content attributes:
Global attributes
DOM interface:
Uses HTMLElement.

The nav element represents a section of a page that links to other pages or to parts within the page: a section with navigation links. Not all groups of links on a page need to be in a nav element — only sections that consist of major navigation blocks are appropriate for the nav element. In particular, it is common for footers to have a list of links to various key parts of a site, but the footer element is more appropriate in such cases, and no nav element is necessary for those links.

In the following example, the page has several places where links are present, but only one of those places is considered a navigation section.

<body>
 <header>
  <h1>Wake up sheeple!</h1>
  <p><a href="news.html">News</a> -
     <a href="blog.html">Blog</a> -
     <a href="forums.html">Forums</a></p>
  <p>Last Modified: <time>2009-04-01</time></p>
  <nav>
   <h1>Navigation</h1>
   <ul>
    <li><a href="articles.html">Index of all articles</a></li>
    <li><a href="today.html">Things sheeple need to wake up for today</a></li>
    <li><a href="successes.html">Sheeple we have managed to wake</a></li>
   </ul>
  </nav>
 </header>
 <article>
  <p>...page content would be here...</p>
 </article>
 <footer>
  <p>Copyright © 2006 The Example Company</p>
  <p><a href="about.html">About</a> -
     <a href="policy.html">Privacy Policy</a> -
     <a href="contact.html">Contact Us</a></p>
 </footer>
</body>

In the following example, there are two nav elements, one for primary navigation around the site, and one for secondary navigation around the page itself.

<body>
 <h1>The Wiki Center Of Exampland</h1>
 <nav>
  <ul>
   <li><a href="/">Home</a></li>
   <li><a href="/events">Current Events</a></li>
   ...more...
  </ul>
 </nav>
 <article>
  <header>
   <h1>Demos in Exampland</h1>
   <nav>
    <ul>
     <li><a href="#public">Public demonstrations</a></li>
     <li><a href="#destroy">Demolitions</a></li>
     ...more...
    </ul>
   </nav>
  </header>
  <section id="public">
   <h1>Public demonstrations</h1>
   <p>...more...</p>
  </section>
  <section id="destroy">
   <h1>Demolitions</h1>
   <p>...more...</p>
  </section>
  ...more...
  <footer>
   <p><a href="?edit">Edit</a> | <a href="?delete">Delete</a> | <a href="?Rename">Rename</a></p>
  </footer>
 </article>
 <footer>
  <p><small>© copyright 1998 Exampland Emperor</small></p>
 </footer>
</body>

4.4.4 The article element

Status: Last call for comments

Categories
Flow content.
Sectioning content.
formatBlock candidate.
Contexts in which this element may be used:
Where flow content is expected.
Content model:
Flow content.
Content attributes:
Global attributes
cite
pubdate
DOM interface:
interface HTMLArticleElement : HTMLElement {
           attribute DOMString cite;
           attribute DOMString pubDate;
};

The article element represents a section of a page that consists of a composition that forms an independent part of a document, page, or site. This could be a forum post, a magazine or newspaper article, a Web log entry, a user-submitted comment, or any other independent item of content.

An article element is "independent" in the sense that its contents could stand alone, for example in syndication.

When article elements are nested, the inner article elements represent articles that are in principle related to the contents of the outer article. For instance, a Web log entry on a site that accepts user-submitted comments could represent the comments as article elements nested within the article element for the Web log entry.

Author information associated with an article element (q.v. the address element) does not apply to nested article elements.

The cite attribute may be used if the content of the article was taken from another page (e.g. syndicating content from multiple sources on one page). The attribute, if present, must contain a valid URL referencing the original source.

The pubdate attribute may be used to specify the time and date that the article was first published. If present, the pubdate attribute must be a valid global date and time string value.

4.4.5 The aside element

Status: Last call for comments

Categories
Flow content.
Sectioning content.
formatBlock candidate.
Contexts in which this element may be used:
Where flow content is expected.
Content model:
Flow content.
Content attributes:
Global attributes
DOM interface:
Uses HTMLElement.

The aside element represents a section of a page that consists of content that is tangentially related to the content around the aside element, and which could be considered separate from that content. Such sections are often represented as sidebars in printed typography.

The element can also be used for typographical effects like pull quotes.

It's not appropriate to use the aside element just for parentheticals, since those are part of the main flow of the document.

The following example shows how an aside is used to mark up background material on Switzerland in a much longer news story on Europe.

<aside>
 <h1>Switzerland</h1>
 <p>Switzerland, a land-locked country in the middle of geographic
 Europe, has not joined the geopolitical European Union, though it is
 a signatory to a number of European treaties.</p>
</aside>

The following example shows how an aside is used to mark up a pull quote in a longer article.

...

<p>He later joined a large company, continuing on the same work.
<q>I love my job. People ask me what I do for fun when I'm not at
work. But I'm paid to do my hobby, so I never know what to
answer. Some people wonder what they would do if they didn't have to
work... but I know what I would do, because I was unemployed for a
year, and I filled that time doing exactly what I do
now.</q></p>

<aside>
 <q> People ask me what I do for fun when I'm not at work. But I'm
 paid to do my hobby, so I never know what to answer. </q>
</aside>

<p>Of course his work — or should that be hobby? —
isn't his only passion. He also enjoys other pleasures.</p>

...

4.4.6 The h1, h2, h3, h4, h5, and h6 elements

Categories
Flow content.
Heading content.
formatBlock candidate.
Contexts in which this element may be used:
Where flow content is expected.
Content model:
Phrasing content.
Content attributes:
Global attributes
DOM interface:
interface HTMLHeadingElement : HTMLElement {};

These elements represent headings for their sections.

The semantics and meaning of these elements are defined in the section on headings and sections.

These elements have a rank given by the number in their name. The h1 element is said to have the highest rank, the h6 element has the lowest rank, and two elements with the same name have equal rank.

4.4.7 The hgroup element

Status: Last call for comments

Categories
Flow content.
Heading content.
formatBlock candidate.
Contexts in which this element may be used:
Where flow content is expected.
Content model:
One or more h1, h2, h3, h4, h5, and/or h6 elements.
Content attributes:
Global attributes
DOM interface:
Uses HTMLElement.

The hgroup element represents the heading of a section. The element is used to group a set of h1–h6 elements when the heading has multiple levels, such as subheadings, alternative titles, or taglines.

The point of hgroup is to mask an h2 element (that acts as a secondary title) from the outline algorithm.

For the purposes of document summaries, outlines, and the like, the text of hgroup elements is defined to be the text of the highest ranked h1–h6 element descendant of the hgroup element, if there are any such elements, and the first such element if there are multiple elements with that rank. If there are no such elements, then the text of the hgroup element is the empty string.

Other elements of heading content in the hgroup element indicate subheadings or subtitles.

The rank of an hgroup element is the rank of the highest-ranked h1–h6 element descendant of the hgroup element, if there are any such elements, or otherwise the same as for an h1 element (the highest rank).

The section on headings and sections defines how hgroup elements are assigned to individual sections.

Here are some examples of valid headings. In each case, the emphasized text represents the text that would be used as the heading in an application extracting heading data and ignoring subheadings.

<hgroup>
 <h1>The reality dysfunction</h1>
 <h2>Space is not the only void</h2>
</hgroup>
<hgroup>
 <h1>Dr. Strangelove</h1>
 <h2>Or: How I Learned to Stop Worrying and Love the Bomb</h2>
</hgroup>

4.4.8 The header element

Status: Last call for comments

Categories
Flow content.
formatBlock candidate.
Contexts in which this element may be used:
Where flow content is expected.
Content model:
Flow content, but with no header or footer element descendants.
Content attributes:
Global attributes
DOM interface:
Uses HTMLElement.

The header element represents a group of introductory or navigational aids.

A header element is intended to usually contain the section's heading (an h1–h6 element or an hgroup element), but this is not required. The header element can also be used to wrap a section's table of contents, a search form, or any relevant logos.

Here are some sample headers. This first one is for a game:

<header>
 <p>Welcome to...</p>
 <h1>Voidwars!</h1>
</header>

The following snippet shows how the element can be used to mark up a specification's header:

<header>
 <hgroup>
  <h1>Scalable Vector Graphics (SVG) 1.2</h1>
  <h2>W3C Working Draft 27 October 2004</h2>
 </hgroup>
 <dl>
  <dt>This version:</dt>
  <dd><a href="http://www.w3.org/TR/2004/WD-SVG12-20041027/">http://www.w3.org/TR/2004/WD-SVG12-20041027/</a></dd>
  <dt>Previous version:</dt>
  <dd><a href="http://www.w3.org/TR/2004/WD-SVG12-20040510/">http://www.w3.org/TR/2004/WD-SVG12-20040510/</a></dd>
  <dt>Latest version of SVG 1.2:</dt>
  <dd><a href="http://www.w3.org/TR/SVG12/">http://www.w3.org/TR/SVG12/</a></dd>
  <dt>Latest SVG Recommendation:</dt>
  <dd><a href="http://www.w3.org/TR/SVG/">http://www.w3.org/TR/SVG/</a></dd>
  <dt>Editor:</dt>
  <dd>Dean Jackson, W3C, <a href="mailto:dean@w3.org">dean@w3.org</a></dd>
  <dt>Authors:</dt>
  <dd>See <a href="#authors">Author List</a></dd>
 </dl>
 <p class="copyright"><a href="http://www.w3.org/Consortium/Legal/ipr-notic ...
</header>

The header element is not sectioning content; it doesn't introduce a new section.

In this example, the page has a page heading given by the h1 element, and two subsections whose headings are given by h2 elements. The content after the header element is still part of the last subsection started in the header element, because the header element doesn't take part in the outline algorithm.

<body>
 <header>
  <h1>Little Green Guys With Guns</h1>
  <nav>
   <ul>
    <li><a href="/games">Games</a> |
    <li><a href="/forum">Forum</a> |
    <li><a href="/download">Download</a>
   </ul>
  </nav>
  <h2>Important News</h2> <!-- this starts a second subsection -->
  <!-- this is part of the subsection entitled "Important News" -->
  <p>To play today's games you will need to update your client.</p>
  <h2>Games</h2> <!-- this starts a third subsection -->
 </header>
 <p>You have three active games:</p>
 <!-- this is still part of the subsection entitled "Games" -->
 ...

Status: Last call for comments

Categories
Flow content.
formatBlock candidate.
Contexts in which this element may be used:
Where flow content is expected.
Content model:
Flow content, but with no heading content descendants, no sectioning content descendants, and no header or footer element descendants.
Content attributes:
Global attributes
DOM interface:
Uses HTMLElement.

The footer element represents a footer for its nearest ancestor sectioning content. A footer typically contains information about its section such as who wrote it, links to related documents, copyright data, and the like.

Contact information belongs in an address element, possibly itself inside a footer.

Footers don't necessarily have to appear at the end of a section, though they usually do.

The footer element is inappropriate for containing entire sections. For appendices, indexes, long colophons, verbose license agreements, and other such content which needs sectioning with headings and so forth, regular section elements should be used, not a footer.

Here is a page with two footers, one at the top and one at the bottom, with the same content:

<body>
 <footer><a href="../">Back to index...</a></footer>
 <hgroup>
  <h1>Lorem ipsum</h1>
  <h2>The ipsum of all lorems</h2>
 </hgroup>
 <p>A dolor sit amet, consectetur adipisicing elit, sed do eiusmod
 tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim
 veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex
 ea commodo consequat. Duis aute irure dolor in reprehenderit in
 voluptate velit esse cillum dolore eu fugiat nulla
 pariatur. Excepteur sint occaecat cupidatat non proident, sunt in
 culpa qui officia deserunt mollit anim id est laborum.</p>
 <footer><a href="../">Back to index...</a></footer>
</body>

4.4.10 The address element

Status: Implemented and widely deployed

Categories
Flow content.
formatBlock candidate.
Contexts in which this element may be used:
Where flow content is expected.
Content model:
Flow content, but with no heading content descendants, no sectioning content descendants, and no header, footer, or address element descendants.
Content attributes:
Global attributes
DOM interface:
Uses HTMLElement.

The address element represents the contact information for its nearest article or body element ancestor. If that is the body element, then the contact information applies to the document as a whole.

For example, a page at the W3C Web site related to HTML might include the following contact information:

<ADDRESS>
 <A href="../People/Raggett/">Dave Raggett</A>,
 <A href="../People/Arnaud/">Arnaud Le Hors</A>,
 contact persons for the <A href="Activity">W3C HTML Activity</A>
</ADDRESS>

The address element must not be used to represent arbitrary addresses (e.g. postal addresses), unless those addresses are in fact the relevant contact information. (The p element is the appropriate element for marking up postal addresses in general.)

The address element must not contain information other than contact information.

For example, the following is non-conforming use of the address element:

<ADDRESS>Last Modified: 1999/12/24 23:37:50</ADDRESS>

Typically, the address element would be included along with other information in a footer element.

Contact information for one sectioning content element, e.g. an aside element, does not apply to its ancestor elements, e.g. the page's body.

4.4.11 Headings and sections

Status: Working draft

The h1–h6 elements and the hgroup element are headings.

The first element of heading content in an element of sectioning content represents the heading for that section. Subsequent headings of equal or higher rank start new (implied) sections, headings of lower rank start implied subsections that are part of the previous one. In both cases, the element represents the heading of the implied section.

Sectioning content elements are always considered subsections of their nearest ancestor element of sectioning content, regardless of what implied sections other headings may have created.

Certain elements are said to be sectioning roots, including blockquote and td elements. These elements can have their own outlines, but the sections and headings inside these elements do not contribute to the outlines of their ancestors.

For the following fragment:

<body>
 <h1>Foo</h1>
 <h2>Bar</h2>
 <blockquote>
  <h3>Bla</h3>
 </blockquote>
 <p>Baz</p>
 <h2>Quux</h2>
 <section>
  <h3>Thud</h3>
 </section>
 <p>Grunt</p>
</body>

...the structure would be:

  1. Foo (heading of explicit body section, containing the "Grunt" paragraph)
    1. Bar (heading starting implied section, containing a block quote and the "Baz" paragraph)
    2. Quux (heading starting implied section)
    3. Thud (heading of explicit section section)

Notice how the section ends the earlier implicit section so that a later paragraph ("Grunt") is back at the top level.

Sections may contain headings of any rank, but authors are strongly encouraged to either use only h1 elements, or to use elements of the appropriate rank for the section's nesting level.

Authors are also encouraged to explicitly wrap sections in elements of sectioning content, instead of relying on the implicit sections generated by having multiple headings in one element of sectioning content.

For example, the following is correct:

<body>
 <h4>Apples</h4>
 <p>Apples are fruit.</p>
 <section>
  <h2>Taste</h2>
  <p>They taste lovely.</p>
  <h6>Sweet</h6>
  <p>Red apples are sweeter than green ones.</p>
  <h1>Color</h1>
  <p>Apples come in various colors.</p>
 </section>
</body>

However, the same document would be more clearly expressed as:

<body>
 <h1>Apples</h1>
 <p>Apples are fruit.</p>
 <section>
  <h2>Taste</h2>
  <p>They taste lovely.</p>
  <section>
   <h3>Sweet</h3>
   <p>Red apples are sweeter than green ones.</p>
  </section>
 </section>
 <section>
  <h2>Color</h2>
  <p>Apples come in various colors.</p>
 </section>
</body>

Both of the documents above are semantically identical and would produce the same outline in compliant user agents.

4.4.11.1 Creating an outline

The outline for a sectioning content element or a sectioning root element consists of a list of one or more potentially nested sections. A section is a container that corresponds to some nodes in the original DOM tree. Each section can have one heading associated with it, and can contain any number of further nested sections. (The sections in the outline aren't section elements, though some may correspond to such elements — they are merely conceptual sections.)

The following markup fragment:

<body>
 <h1>A</h1>
 <p>B</p>
 <h2>C</h2>
 <p>D</p>
 <h2>E</h2>
 <p>F</p>
</body>

...results in the following outline being created for the body node (and thus the entire document):

  1. Section created for body node.

    Associated with heading "A".

    Also associated with paragraph "B".

    Nested sections:

    1. Section implied for first h2 element.

      Associated with heading "C".

      Also associated with paragraph "D".

      No nested sections.

    2. Section implied for second h2 element.

      Associated with heading "E".

      Also associated with paragraph "F".

      No nested sections.

4.4.11.2 Distinguishing site-wide headings from page headings

If a page starts with a heading that is common to the whole site, the document must be authored such that, in the document's outline, ignoring any sections created for nav and aside elements and any of their descendants, the tree has only one root section, the body element's section, its heading is the site-wide heading, the body element has just one subsection, that subsection is created by an article element, and that article's heading is the page heading.

If a page does not contain a site-wide heading, then the page must be authored such that, in the document's outline, ignoring any sections created for nav and aside elements and any of their descendants, either the body element has no subsections, or it has more than one subsection, or it has a single subsection but that subsection is not created by an article element, or there is more than one section at the root of the outline.

Conceptually, a site is thus a document with many articles — when those articles are split into many pages, the heading of the original single page becomes the heading of the site, repeated on every page.

4.5 Grouping content

Status: Last call for comments

4.5.1 The p element

Status: Implemented and widely deployed

Categories
Flow content.
formatBlock candidate.
Contexts in which this element may be used:
Where flow content is expected.
Content model:
Phrasing content.
Content attributes:
Global attributes
DOM interface:
interface HTMLParagraphElement : HTMLElement {};

The p element represents a paragraph.

The following examples are conforming HTML fragments:

<p>The little kitten gently seated himself on a piece of
carpet. Later in his life, this would be referred to as the time the
cat sat on the mat.</p>
<fieldset>
 <legend>Personal information</legend>
 <p>
   <label>Name: <input name="n"></label>
   <label><input name="anon" type="checkbox"> Hide from other users</label>
 </p>
 <p><label>Address: <textarea name="a"></textarea></label></p>
</fieldset>
<p>There was once an example from Femley,<br>
Whose markup was of dubious quality.<br>
The validator complained,<br>
So the author was pained,<br>
To move the error from the markup to the rhyming.</p>

The p element should not be used when a more specific element is more appropriate.

The following example is technically correct:

<section>
 <!-- ... -->
 <p>Last modified: 2001-04-23</p>
 <p>Author: fred@example.com</p>
</section>

However, it would be better marked-up as:

<section>
 <!-- ... -->
 <footer>Last modified: 2001-04-23</footer>
 <address>Author: fred@example.com</address>
</section>

Or:

<section>
 <!-- ... -->
 <footer>
  <p>Last modified: 2001-04-23</p>
  <address>Author: fred@example.com</address>
 </footer>
</section>

4.5.2 The hr element

Status: Implemented and widely deployed

Categories
Flow content.
Contexts in which this element may be used:
Where flow content is expected.
Content model:
Empty.
Content attributes:
Global attributes
DOM interface:
interface HTMLHRElement : HTMLElement {};

The hr element represents a paragraph-level thematic break, e.g. a scene change in a story, or a transition to another topic within a section of a reference book.

4.5.3 The br element

Status: Implemented and widely deployed

Categories
Flow content.
Phrasing content.
Contexts in which this element may be used:
Where phrasing content is expected.
Content model:
Empty.
Content attributes:
Global attributes
DOM interface:
interface HTMLBRElement : HTMLElement {};

The br element represents a line break.

br elements must be empty. Any content inside br elements must not be considered part of the surrounding text.

br elements must be used only for line breaks that are actually part of the content, as in poems or addresses.

The following example is correct usage of the br element:

<p>P. Sherman<br>
42 Wallaby Way<br>
Sydney</p>

br elements must not be used for separating thematic groups in a paragraph.

The following examples are non-conforming, as they abuse the br element:

<p><a ...>34 comments.</a><br>
<a ...>Add a comment.</a></p>
<p><label>Name: <input name="name"></label><br>
<label>Address: <input name="address"></label></p>

Here are alternatives to the above, which are correct:

<p><a ...>34 comments.</a></p>
<p><a ...>Add a comment.</a></p>
<p><label>Name: <input name="name"></label></p>
<p><label>Address: <input name="address"></label></p>

If a paragraph consists of nothing but a single br element, it represents a placeholder blank line (e.g. as in a template). Such blank lines must not be used for presentation purposes.

4.5.4 The pre element

Status: Implemented and widely deployed

Categories
Flow content.
formatBlock candidate.
Contexts in which this element may be used:
Where flow content is expected.
Content model:
Phrasing content.
Content attributes:
Global attributes
DOM interface:
interface HTMLPreElement : HTMLElement {};

The pre element represents a block of preformatted text, in which structure is represented by typographic conventions rather than by elements.

In the the HTML syntax, a leading newline character immediately following the pre element start tag is stripped.

Some examples of cases where the pre element could be used:

Authors are encouraged to consider how preformatted text will be experienced when the formatting is lost, as will be the case for users of speech synthesizers, braille displays, and the like. For cases like ASCII art, it is likely that an alternative presentation, such as a textual description, would be more universally accessible to the readers of the document.

To represent a block of computer code, the pre element can be used with a code element; to represent a block of computer output the pre element can be used with a samp element. Similarly, the kbd element can be used within a pre element to indicate text that the user is to enter.

In the following snippet, a sample of computer code is presented.

<p>This is the <code>Panel</code> constructor:</p>
<pre><code>function Panel(element, canClose, closeHandler) {
  this.element = element;
  this.canClose = canClose;
  this.closeHandler = function () { if (closeHandler) closeHandler() };
}</code></pre>

In the following snippet, samp and kbd elements are mixed in the contents of a pre element to show a session of Zork I.

<pre><samp>You are in an open field west of a big white house with a boarded
front door.
There is a small mailbox here.

></samp> <kbd>open mailbox</kbd>

<samp>Opening the mailbox reveals:
A leaflet.

></samp></pre>

The following shows a contemporary poem that uses the pre element to preserve its unusual formatting, which forms an intrinsic part of the poem itself.

<pre>                maxling

it is with a          heart
               heavy

that i admit loss of a feline
        so           loved

a friend lost to the
        unknown
                                (night)

~cdr 11dec07</pre>

4.5.5 The dialog element

Status: Working draft

Categories
Flow content.
Contexts in which this element may be used:
Where flow content is expected.
Content model:
Zero or more pairs of one dt element followed by one dd element.
Content attributes:
Global attributes
DOM interface:
Uses HTMLElement.

The dialog element represents a conversation, meeting minutes, a chat transcript, a dialog in a screenplay, an instant message log, or some other construct in which different players take turns in discourse.

Each part of the conversation must have an explicit talker (or speaker) given by a dt element, and a discourse (or quote) given by a dd element.

This example demonstrates this using an extract from Abbot and Costello's famous sketch, Who's on first:

<dialog>
 <dt> Costello
 <dd> Look, you gotta first baseman?
 <dt> Abbott
 <dd> Certainly.
 <dt> Costello
 <dd> Who's playing first?
 <dt> Abbott
 <dd> That's right.
 <dt> Costello
 <dd> When you pay off the first baseman every month, who gets the money?
 <dt> Abbott
 <dd> Every dollar of it.
</dialog>

Text in a dt element in a dialog element is implicitly the source of the text given in the following dd element, and the contents of the dd element are implicitly a quote from that speaker. There is thus no need to include cite, q, or blockquote elements in this markup. Indeed, a q element inside a dd element in a conversation would actually imply the people talking were themselves quoting another work. See the cite, q, and blockquote elements for other ways to cite or quote.

4.5.6 The blockquote element

Status: Last call for comments

Categories
Flow content.
Sectioning root.
formatBlock candidate.
Contexts in which this element may be used:
Where flow content is expected.
Content model:
Flow content.
Content attributes:
Global attributes
cite
DOM interface:
interface HTMLQuoteElement : HTMLElement {
           attribute DOMString cite;
};

The HTMLQuoteElement interface is also used by the q element.

The blockquote element represents a section that is quoted from another source.

Content inside a blockquote must be quoted from another source, whose address, if it has one, should be cited in the cite attribute.

If the cite attribute is present, it must be a valid URL.

The best way to represent a conversation is not with the cite and blockquote elements, but with the dialog element.

This next example shows the use of cite alongside blockquote:

<p>His next piece was the aptly named <cite>Sonnet 130</cite>:</p>
<blockquote cite="http://quotes.example.org/s/sonnet130.html">
  <p>My mistress' eyes are nothing like the sun,<br>
  Coral is far more red, than her lips red,<br>
  ...

4.5.7 The ol element

Status: Working draft

Categories
Flow content.
Contexts in which this element may be used:
Where flow content is expected.
Content model:
Zero or more li elements.
Content attributes:
Global attributes
reversed
start
DOM interface:
interface HTMLOListElement : HTMLElement {
           attribute boolean reversed;
           attribute long start;
};

The ol element represents a list of items, where the items have been intentionally ordered, such that changing the order would change the meaning of the document.

The items of the list are the li element child nodes of the ol element, in tree order.

The reversed attribute is a boolean attribute. If present, it indicates that the list is a descending list (..., 3, 2, 1). If the attribute is omitted, the list is an ascending list (1, 2, 3, ...).

The start attribute, if present, must be a valid integer giving the ordinal value of the first list item.

The following markup shows a list where the order matters, and where the ol element is therefore appropriate. Compare this list to the equivalent list in the ul section to see an example of the same items using the ul element.

<p>I have lived in the following countries (given in the order of when
I first lived there):</p>
<ol>
 <li>Switzerland
 <li>United Kingdom
 <li>United States
 <li>Norway
</ol>

Note how changing the order of the list changes the meaning of the document. In the following example, changing the relative order of the first two items has changed the birthplace of the author:

<p>I have lived in the following countries (given in the order of when
I first lived there):</p>
<ol>
 <li>United Kingdom
 <li>Switzerland
 <li>United States
 <li>Norway
</ol>

4.5.8 The ul element

Status: Implemented and widely deployed

Categories
Flow content.
Contexts in which this element may be used:
Where flow content is expected.
Content model:
Zero or more li elements.
Content attributes:
Global attributes
DOM interface:
interface HTMLUListElement : HTMLElement {};

The ul element represents a list of items, where the order of the items is not important — that is, where changing the order would not materially change the meaning of the document.

The items of the list are the li element child nodes of the ul element.

The following markup shows a list where the order does not matter, and where the ul element is therefore appropriate. Compare this list to the equivalent list in the ol section to see an example of the same items using the ol element.

<p>I have lived in the following countries:</p>
<ul>
 <li>Norway
 <li>Switzerland
 <li>United Kingdom
 <li>United States
</ul>

Note that changing the order of the list does not change the meaning of the document. The items in the snippet above are given in alphabetical order, but in the snippet below they are given in order of the size of their current account balance in 2007, without changing the meaning of the document whatsoever:

<p>I have lived in the following countries:</p>
<ul>
 <li>Switzerland
 <li>Norway
 <li>United Kingdom
 <li>United States
</ul>

4.5.9 The li element

Status: Implemented and widely deployed

Categories
None.
Contexts in which this element may be used:
Inside ol elements.
Inside ul elements.
Inside menu elements.
Content model:
Flow content.
Content attributes:
Global attributes
If the element is a child of an ol element: value
DOM interface:
interface HTMLLIElement : HTMLElement {
           attribute long value;
};

The li element represents a list item. If its parent element is an ol, ul, or menu element, then the element is an item of the parent element's list, as defined for those elements. Otherwise, the list item has no defined list-related relationship to any other li element.

The value attribute, if present, must be a valid integer giving the ordinal value of the list item.

The following example, the top ten movies are listed (in reverse order). Note the way the list is given a title by using a figure element and its legend.

<figure>
 <legend>The top 10 movies of all time</legend>
 <ol>
  <li value="10"><cite>Josie and the Pussycats</cite>, 2001</li>
  <li value="9"><cite lang="sh">Црна мачка, бели мачор</cite>, 1998</li>
  <li value="8"><cite>A Bug's Life</cite>, 1998</li>
  <li value="7"><cite>Toy Story</cite>, 1995</li>
  <li value="6"><cite>Monsters, Inc</cite>, 2001</li>
  <li value="5"><cite>Cars</cite>, 2006</li>
  <li value="4"><cite>Toy Story 2</cite>, 1999</li>
  <li value="3"><cite>Finding Nemo</cite>, 2003</li>
  <li value="2"><cite>The Incredibles</cite>, 2004</li>
  <li value="1"><cite>Ratatouille</cite>, 2007</li>
 </ol>
</figure>

The markup could also be written as follows, using the reversed attribute on the ol element:

<figure>
 <legend>The top 10 movies of all time</legend>
 <ol reversed>
  <li><cite>Josie and the Pussycats</cite>, 2001</li>
  <li><cite lang="sh">Црна мачка, бели мачор</cite>, 1998</li>
  <li><cite>A Bug's Life</cite>, 1998</li>
  <li><cite>Toy Story</cite>, 1995</li>
  <li><cite>Monsters, Inc</cite>, 2001</li>
  <li><cite>Cars</cite>, 2006</li>
  <li><cite>Toy Story 2</cite>, 1999</li>
  <li><cite>Finding Nemo</cite>, 2003</li>
  <li><cite>The Incredibles</cite>, 2004</li>
  <li><cite>Ratatouille</cite>, 2007</li>
 </ol>
</figure>

If the li element is the child of a menu element and itself has a child that defines a command, then the li element will match the :enabled and :disabled pseudo-classes in the same way as the first such child element does.

4.5.10 The dl element

Status: Implemented and widely deployed

Categories
Flow content.
Contexts in which this element may be used:
Where flow content is expected.
Content model:
Zero or more groups each consisting of one or more dt elements followed by one or more dd elements.
Content attributes:
Global attributes
DOM interface:
interface HTMLDListElement : HTMLElement {};

The dl element represents an association list consisting of zero or more name-value groups (a description list). Each group must consist of one or more names (dt elements) followed by one or more values (dd elements).

Name-value groups may be terms and definitions, metadata topics and values, or any other groups of name-value data.

The values within a group are alternatives; multiple paragraphs forming part of the same value must all be given within the same dd element.

The order of the list of groups, and of the names and values within each group, may be significant.

In the following example, one entry ("Authors") is linked to two values ("John" and "Luke").

<dl>
 <dt> Authors
 <dd> John
 <dd> Luke
 <dt> Editor
 <dd> Frank
</dl>

In the following example, one definition is linked to two terms.

<dl>
 <dt lang="en-US"> <dfn>color</dfn> </dt>
 <dt lang="en-GB"> <dfn>colour</dfn> </dt>
 <dd> A sensation which (in humans) derives from the ability of
 the fine structure of the eye to distinguish three differently
 filtered analyses of a view. </dd>
</dl>

The following example illustrates the use of the dl element to mark up metadata of sorts. At the end of the example, one group has two metadata labels ("Authors" and "Editors") and two values ("Robert Rothman" and "Daniel Jackson").

<dl>
 <dt> Last modified time </dt>
 <dd> 2004-12-23T23:33Z </dd>
 <dt> Recommended update interval </dt>
 <dd> 60s </dd>
 <dt> Authors </dt>
 <dt> Editors </dt>
 <dd> Robert Rothman </dd>
 <dd> Daniel Jackson </dd>
</dl>

The following example shows the dl element used to give a set of instructions. The order of the instructions here is important (in the other examples, the order of the blocks was not important).

<p>Determine the victory points as follows (use the
first matching case):</p>
<dl>
 <dt> If you have exactly five gold coins </dt>
 <dd> You get five victory points </dd>
 <dt> If you have one or more gold coins, and you have one or more silver coins </dt>
 <dd> You get two victory points </dd>
 <dt> If you have one or more silver coins </dt>
 <dd> You get one victory point </dd>
 <dt> Otherwise </dt>
 <dd> You get no victory points </dd>
</dl>

The following snippet shows a dl element being used as a glossary. Note the use of dfn to indicate the word being defined.

<dl>
 <dt><dfn>Apartment</dfn>, n.</dt>
 <dd>An execution context grouping one or more threads with one or
 more COM objects.</dd>
 <dt><dfn>Flat</dfn>, n.</dt>
 <dd>A deflated tire.</dd>
 <dt><dfn>Home</dfn>, n.</dt>
 <dd>The user's login directory.</dd>
</dl>

The dl element is inappropriate for marking up dialogue. For an example of how to mark up dialogue, see the dialog element.

4.5.11 The dt element

Status: Implemented and widely deployed

Categories
None.
Contexts in which this element may be used:
Before dd or dt elements inside dl elements.
Before a dd element inside a dialog element.
Content model:
Phrasing content.
Content attributes:
Global attributes
DOM interface:
Uses HTMLElement.

The dt element represents the term, or name, part of a term-description group in a description list (dl element), and the talker, or speaker, part of a talker-discourse pair in a conversation (dialog element).

The dt element itself, when used in a dl element, does not indicate that its contents are a term being defined, but this can be indicated using the dfn element.

If the dt element is the child of a dialog element, and it further contains a time element, then that time element represents a timestamp for when the associated discourse (dd element) was said, and is not part of the name of the talker.

The following extract shows how an IM conversation log could be marked up.

<dialog>
 <dt> <time>14:22</time> egof
 <dd> I'm not that nerdy, I've only seen 30% of the star trek episodes
 <dt> <time>14:23</time> kaj
 <dd> if you know what percentage of the star trek episodes you have seen, you are inarguably nerdy
 <dt> <time>14:23</time> egof
 <dd> it's unarguably
 <dt> <time>14:24</time> kaj
 <dd> you are not helping your case
</dialog>

4.5.12 The dd element

Status: Implemented and widely deployed

Categories
None.
Contexts in which this element may be used:
After dt or dd elements inside dl elements.
After a dt element inside a dialog element.
Content model:
Flow content.
Content attributes:
Global attributes
DOM interface:
Uses HTMLElement.

The dd element represents the description, definition, or value, part of a term-description group in a description list (dl element), and the discourse, or quote, part in a conversation (dialog element).

A dl can be used to define a vocabulary list, like in a dictionary. In the following example, each entry, given by a dt with a dfn, has several dds, showing the various parts of the definition.

<dl>
 <dt><dfn>happiness</dfn></dt>
 <dd class="pronunciation">/'hæ p. nes/</dd>
 <dd class="part-of-speech"><i><abbr>n.</abbr></i></dd>
 <dd>The state of being happy.</dd>
 <dd>Good fortune; success. <q>Oh <b>happiness</b>! It worked!</q></dd>
 <dt><dfn>rejoice</dfn></dt>
 <dd class="pronunciation">/ri jois'/</dd>
 <dd><i class="part-of-speech"><abbr>v.intr.</abbr></i> To be delighted oneself.</dd>
 <dd><i class="part-of-speech"><abbr>v.tr.</abbr></i> To cause one to be delighted.</dd>
</dl>

4.5.13 Common grouping idioms

4.5.13.1 Tag clouds

This specification does not define any markup specifically for marking up lists of keywords that apply to a group of pages (also known as tag clouds). In general, authors are encouraged to either mark up such lists using ul elements with explicit inline counts that are then hidden and turned into a presentational effect using a style sheet, or to use SVG.

Here, three tags are included in a short tag cloud:

<style>
@media screen, print, handheld, tv {
  /* should be ignored by non-visual browsers */
  .tag-cloud > li > span { display: none; }
  .tag-cloud > li { display: inline; }
  .tag-cloud-1 { font-size: 0.7em; }
  .tag-cloud-2 { font-size: 0.9em; }
  .tag-cloud-3 { font-size: 1.1em; }
  .tag-cloud-4 { font-size: 1.3em; }
  .tag-cloud-5 { font-size: 1.5em; }
}
</style>
...
<ul class="tag-cloud">
 <li class="tag-cloud-4"><a title="28 instances" href="/t/apple">apple</a> <span>(popular)</span>
 <li class="tag-cloud-2"><a title="6 instances"  href="/t/kiwi">kiwi</a> <span>(rare)</span>
 <li class="tag-cloud-5"><a title="41 instances" href="/t/pear">pear</a> <span>(very popular)</span>
</ul>

The actual frequency of each tag is given using the title attribute. A CSS style sheet is provided to convert the markup into a cloud of differently-sized words, but for user agents that do not support CSS or are not visual, the markup contains annotations like "(popular)" or "(rare)" to categorize the various tags by frequency, thus enabling all users to benefit from the information.

The ul element is used (rather than ol) because the order is not particular important: while the list is in fact ordered alphabetically, it would convey the same information if ordered by, say, the length of the tag.

The tag rel-keyword is not used on these a elements because they do not represent tags that apply to the page itself; they are just part of an index listing the tags themselves.

4.6 Text-level semantics

4.6.1 The a element

Status: Last call for comments

Categories
Flow content.
When the element only contains phrasing content: phrasing content.
Interactive content.
Contexts in which this element may be used:
Where phrasing content is expected.
Content model:
Transparent, but there must be no interactive content descendant.
Content attributes:
Global attributes
href
target
ping
rel
media
hreflang
type
DOM interface:
interface HTMLAnchorElement : HTMLElement {
  stringifier attribute DOMString href;
           attribute DOMString target;
           attribute DOMString ping;
           attribute DOMString rel;
  readonly attribute DOMTokenList relList;
           attribute DOMString media;
           attribute DOMString hreflang;
           attribute DOMString type;

  // URL decomposition attributes
           attribute DOMString protocol;
           attribute DOMString host;
           attribute DOMString hostname;
           attribute DOMString port;
           attribute DOMString pathname;
           attribute DOMString search;
           attribute DOMString hash;
};

If the a element has an href attribute, then it represents a hyperlink (a hypertext anchor).

If the a element has no href attribute, then the element represents a placeholder for where a link might otherwise have been placed, if it had been relevant.

The target, ping, rel, media, hreflang, and type attributes must be omitted if the href attribute is not present.

If a site uses a consistent navigation tool bar on every page, then the link that would normally link to the page itself could be marked up using an a element:

<nav>
 <ul>
  <li> <a href="/">Home</a> </li>
  <li> <a href="/news">News</a> </li>
  <li> <a>Examples</a> </li>
  <li> <a href="/legal">Legal</a> </li>
 </ul>
</nav>

The a element may be wrapped around entire paragraphs, lists, tables, and so forth, even entire sections, so long as there is no interactive content within (e.g. buttons or other links). This example shows how this can be used to make an entire advertising block into a link:

<aside class="advertising">
 <h1>Advertising</h1>
 <a href="http://ad.example.com/?adid=1929&amp;pubid=1422">
  <section>
   <h1>Mellblomatic 9000!</h1>
   <p>Turn all your widgets into mellbloms!</p>
   <p>Only $9.99 plus shipping and handling.</p>
  </section>
 </a>
 <a href="http://ad.example.com/?adid=375&amp;pubid=1422">
  <section>
   <h1>The Mellblom Browser</h1>
   <p>Web browsing at the speed of light.</p>
   <p>No other browser goes faster!</p>
  </section>
 </a>
</aside>

4.6.2 The q element

Status: Working draft

Categories
Flow content.
Phrasing content.
Contexts in which this element may be used:
Where phrasing content is expected.
Content model:
Phrasing content.
Content attributes:
Global attributes
cite
DOM interface:
The q element uses the HTMLQuoteElement interface.

The q element represents some phrasing content quoted from another source.

Quotation punctuation (such as quotation marks) must not appear immediately before, after, or inside q elements; they will be inserted into the rendering by the user agent.

Content inside a q element must be quoted from another source, whose address, if it has one, should be cited in the cite attribute. The source may be fictional, as when quoting characters in a novel or screenplay.

The q element must not be used in place of quotation marks that do not represent quotes; for example, it is inappropriate to use the q element for marking up sarcastic statements.

The use of q elements to mark up quotations is entirely optional; using explicit quotation punctuation without q elements is just as correct.

Here is a simple example of the use of the q element:

<p>The man said <q>Things that are impossible just take
longer</q>. I disagreed with him.</p>

Here is an example with both an explicit citation link in the q element, and an explicit citation outside:

<p>The W3C page <cite>About W3C</cite> says the W3C's
mission is <q cite="http://www.w3.org/Consortium/">To lead the
World Wide Web to its full potential by developing protocols and
guidelines that ensure long-term growth for the Web</q>. I
disagree with this mission.</p>

In the following example, the quotation itself contains a quotation:

<p>In <cite>Example One</cite>, he writes <q>The man
said <q>Things that are impossible just take longer</q>. I
disagreed with him</q>. Well, I disagree even more!</p>

In the following example, quotation marks are used instead of the q element:

<p>His best argument was ❝I disagree❞, which
I thought was laughable.</p>

In the following example, there is no quote — the quotation marks are used to name a word. Use of the q element in this case would be inappropriate.

<p>The word "ineffable" could have been used to describe the disaster
resulting from the campaign's mismanagement.</p>

4.6.3 The cite element

Status: Implemented and widely deployed

Categories
Flow content.
Phrasing content.
Contexts in which this element may be used:
Where phrasing content is expected.
Content model:
Phrasing content.
Content attributes:
Global attributes
DOM interface:
Uses HTMLElement.

The cite element represents the title of a work (e.g. a book, a paper, an essay, a poem, a score, a song, a script, a film, a TV show, a game, a sculpture, a painting, a theatre production, a play, an opera, a musical, an exhibition, etc). This can be a work that is being quoted or referenced in detail (i.e. a citation), or it can just be a work that is mentioned in passing.

A person's name is not the title of a work — even if people call that person a piece of work — and the element must therefore not be used to mark up people's names. (In some cases, the b element might be appropriate for names; e.g. in a gossip article where the names of famous people are keywords rendered with a different style to draw attention to them. In other cases, if an element is really needed, the span element can be used.)

A ship is similarly not a work, and the element must not be used to mark up ship names (the i element can be used for that purpose).

This next example shows a typical use of the cite element:

<p>My favorite book is <cite>The Reality Dysfunction</cite> by
Peter F. Hamilton. My favorite comic is <cite>Pearls Before
Swine</cite> by Stephan Pastis. My favorite track is <cite>Jive
Samba</cite> by the Cannonball Adderley Sextet.</p>

This is correct usage:

<p>According to the Wikipedia article <cite>HTML</cite>, as it
stood in mid-February 2008, leaving attribute values unquoted is
unsafe. This is obviously an over-simplification.</p>

The following, however, is incorrect usage, as the cite element here is containing far more than the title of the work:

<!-- do not copy this example, it is an example of bad usage! -->
<p>According to <cite>the Wikipedia article on HTML</cite>, as it
stood in mid-February 2008, leaving attribute values unquoted is
unsafe. This is obviously an over-simplification.</p>

The cite element is obviously a key part of any citation in a bibliography, but it is only used to mark the title:

<p><cite>Universal Declaration of Human Rights</cite>, United Nations,
December 1948. Adopted by General Assembly resolution 217 A (III).</p>

A citation is not a quote (for which the q element is appropriate).

This is incorrect usage, because cite is not for quotes:

<p><cite>This is wrong!</cite>, said Ian.</p>

This is also incorrect usage, because a person is not a work:

<p><q>This is still wrong!</q>, said <cite>Ian</cite>.</p>

The correct usage does not use a cite element:

<p><q>This is correct</q>, said Ian.</p>

As mentioned above, the b element might be relevant for marking names as being keywords in certain kinds of documents:

<p>And then <b>Ian</b> said <q>this might be right, in a
gossip column, maybe!</q>.</p>

4.6.4 The em element

Status: Implemented and widely deployed

Categories
Flow content.
Phrasing content.
Contexts in which this element may be used:
Where phrasing content is expected.
Content model:
Phrasing content.
Content attributes:
Global attributes
DOM interface:
Uses HTMLElement.

The em element represents stress emphasis of its contents.

The level of emphasis that a particular piece of content has is given by its number of ancestor em elements.

The placement of emphasis changes the meaning of the sentence. The element thus forms an integral part of the content. The precise way in which emphasis is used in this way depends on the language.

These examples show how changing the emphasis changes the meaning. First, a general statement of fact, with no emphasis:

<p>Cats are cute animals.</p>

By emphasizing the first word, the statement implies that the kind of animal under discussion is in question (maybe someone is asserting that dogs are cute):

<p><em>Cats</em> are cute animals.</p>

Moving the emphasis to the verb, one highlights that the truth of the entire sentence is in question (maybe someone is saying cats are not cute):

<p>Cats <em>are</em> cute animals.</p>

By moving it to the adjective, the exact nature of the cats is reasserted (maybe someone suggested cats were mean animals):

<p>Cats are <em>cute</em> animals.</p>

Similarly, if someone asserted that cats were vegetables, someone correcting this might emphasize the last word:

<p>Cats are cute <em>animals</em>.</p>

By emphasizing the entire sentence, it becomes clear that the speaker is fighting hard to get the point across. This kind of emphasis also typically affects the punctuation, hence the exclamation mark here.

<p><em>Cats are cute animals!</em></p>

Anger mixed with emphasizing the cuteness could lead to markup such as:

<p><em>Cats are <em>cute</em> animals!</em></p>

The em element isn't a generic "italics" element. Sometimes, text is intended to stand out from the rest of the paragraph, as if it was in a different mood or voice. For this, the i element is more appropriate.

The em element also isn't intended to convey importance; for that purpose, the strong element is more appropriate.

4.6.5 The strong element

Status: Implemented and widely deployed

Categories
Flow content.
Phrasing content.
Contexts in which this element may be used:
Where phrasing content is expected.
Content model:
Phrasing content.
Content attributes:
Global attributes
DOM interface:
Uses HTMLElement.

The strong element represents strong importance for its contents.

The relative level of importance of a piece of content is given by its number of ancestor strong elements; each strong element increases the importance of its contents.

Changing the importance of a piece of text with the strong element does not change the meaning of the sentence.

Here is an example of a warning notice in a game, with the various parts marked up according to how important they are:

<p><strong>Warning.</strong> This dungeon is dangerous.
<strong>Avoid the ducks.</strong> Take any gold you find.
<strong><strong>Do not take any of the diamonds</strong>,
they are explosive and <strong>will destroy anything within
ten meters.</strong></strong> You have been warned.</p>

4.6.6 The small element

Status: Last call for comments

Categories
Flow content.
Phrasing content.
Contexts in which this element may be used:
Where phrasing content is expected.
Content model:
Phrasing content.
Content attributes:
Global attributes
DOM interface:
Uses HTMLElement.

The small element represents small print or other side comments.

Small print typically features disclaimers, caveats, legal restrictions, or copyrights. Small print is also sometimes used for attribution, or for satisfying licensing requirements.

The small element does not "de-emphasize" or lower the importance of text emphasized by the em element or marked as important with the strong element.

In this example the footer contains contact information and a copyright notice.

<footer>
 <address>
  For more details, contact
  <a href="mailto:js@example.com">John Smith</a>.
 </address>
 <p><small>© copyright 2038 Example Corp.</small></p>
</footer>

In this second example, the small element is used for a side comment in an article.

<p>Example Corp today announced record profits for the
second quarter <small>(Full Disclosure: Foo News is a subsidiary of
Example Corp)</small>, leading to speculation about a third quarter
merger with Demo Group.</p>

This is distinct from a sidebar, which might be multiple paragraphs long and is removed from the main flow of text. In the following example, we see a sidebar from the same article. This sidebar also has small print, indicating the source of the information in the sidebar.

<aside>
 <h1>Example Corp</h1>
 <p>This company mostly creates small software and Web
 sites.</p>
 <p>The Example Corp company mission is "To provide entertainment
 and news on a sample basis".</p>
 <p><small>Information obtained from <a
 href="http://example.com/about.html">example.com</a> home
 page.</small></p>
</aside>

In this last example, the small element is marked as being important small print.

<p><strong><small>Continued use of this service will result in a kiss.</small></strong></p>

4.6.7 The mark element

Status: Working draft

Categories
Flow content.
Phrasing content.
Contexts in which this element may be used:
Where phrasing content is expected.
Content model:
Phrasing content.
Content attributes:
Global attributes
DOM interface:
Uses HTMLElement.

The mark element represents a run of text in one document marked or highlighted for reference purposes, due to its relevance in another context. When used in a quotation or other block of text referred to from the prose, it indicates a highlight that was not originally present but which has been added to bring the reader's attention to a part of the text that might not have been considered important by the original author when the block was originally written, but which is now under previously unexpected scrutiny. When used in the main prose of a document, it indicates a part of the document that has been highlighted due to its likely relevance to the user's current activity.

This example shows how the mark element can be used to bring attention to a particular part of a quotation:

<p lang="en-US">Consider the following quote:</p>
<blockquote lang="en-GB">
 <p>Look around and you will find, no-one's really
 <mark>colour</mark> blind.</p>
</blockquote>
<p lang="en-US">As we can tell from the <em>spelling</em> of the word,
the person writing this quote is clearly not American.</p>

Another example of the mark element is highlighting parts of a document that are matching some search string. If someone looked at a document, and the server knew that the user was searching for the word "kitten", then the server might return the document with one paragraph modified as follows:

<p>I also have some <mark>kitten</mark>s who are visiting me
these days. They're really cute. I think they like my garden! Maybe I
should adopt a <mark>kitten</mark>.</p>

In the following snippet, a paragraph of text refers to a specific part of a code fragment.

<p>The highlighted part below is where the error lies:</p>
<pre><code>var i: Integer;
begin
   i := <mark>1.1</mark>;
end.</code></pre>

This is another example showing the use of mark to highlight a part of quoted text that was originally not emphasized. In this example, common typographic conventions have led the author to explicitly style mark elements in quotes to render in italics.

<article>
 <style>
  blockquote mark, q mark {
    font: inherit; font-style: italic;
    text-decoration: none;
    background: transparent; color: inherit;
  }
  .bubble em {
    font: inherit; font-size: larger;
    text-decoration: underline;
  }
 </style>
 <h1>She knew</h1>
 <p>Did you notice the subtle joke in the joke on panel 4?</p>
 <blockquote>
  <p class="bubble">I didn't <em>want</em> to believe. <mark>Of course
  on some level I realized it was a known-plaintext attack.</mark> But I
  couldn't admit it until I saw for myself.</p>
 </blockquote>
 <p>(Emphasis mine.) I thought that was great. It's so pedantic, yet it
 explains everything neatly.</p>
</article>

Note, incidentally, the distinction between the em element in this example, which is part of the original text being quoted, and the mark element, which is highlighting a part for comment.

The following example shows the difference between denoting the importance of a span of text (strong) as opposed to denoting the relevance of a span of text (mark). It is an extract from a textbook, where the extract has had the parts relevant to the exam highlighted. The safety warnings, important though they may be, are apparently not relevant to the exam.

<h3>Wormhole Physics Introduction</h3>

<p><mark>A wormhole in normal conditions can be held open for a
maximum of just under 39 minutes.</mark> Conditions that can increase
the time include a powerful energy source coupled to one or both of
the gates connecting the wormhole, and a large gravity well (such as a
black hole).</p>

<p><mark>Momentum is preserved across the wormhole. Electromagnetic
radiation can travel in both directions through a wormhole,
but matter cannot.</mark></p>

<p>When a wormhole is created, a vortex normally forms.
<strong>Warning: The vortex caused by the wormhole opening will
annihilate anything in its path.</strong> Vortexes can be avoided when
using sufficiently advanced dialing technology.</p>

<p><mark>An obstruction in a gate will prevent it from accepting a
wormhole connection.</mark></p>

4.6.8 The dfn element

Status: Last call for comments

Categories
Flow content.
Phrasing content.
Contexts in which this element may be used:
Where phrasing content is expected.
Content model:
Phrasing content, but there must be no descendant dfn elements.
Content attributes:
Global attributes
Also, the title attribute has special semantics on this element.
DOM interface:
Uses HTMLElement.

The dfn element represents the defining instance of a term. The paragraph, description list group, or section that is the nearest ancestor of the dfn element must also contain the definition(s) for the term given by the dfn element.

Defining term: If the dfn element has a title attribute, then the exact value of that attribute is the term being defined. Otherwise, if it contains exactly one element child node and no child text nodes, and that child element is an abbr element with a title attribute, then the exact value of that attribute is the term being defined. Otherwise, it is the exact textContent of the dfn element that gives the term being defined.

If the title attribute of the dfn element is present, then it must contain only the term being defined.

The title attribute of ancestor elements does not affect dfn elements.

An a element that links to a dfn element represents an instance of the term defined by the dfn element.

In the following fragment, the term "GDO" is first defined in the first paragraph, then used in the second.

<p>The <dfn><abbr title="Garage Door Opener">GDO</abbr></dfn>
is a device that allows off-world teams to open the iris.</p>
<!-- ... later in the document: -->
<p>Teal'c activated his <abbr title="Garage Door Opener">GDO</abbr>
and so Hammond ordered the iris to be opened.</p>

With the addition of an a element, the reference can be made explicit:

<p>The <dfn id=gdo><abbr title="Garage Door Opener">GDO</abbr></dfn>
is a device that allows off-world teams to open the iris.</p>
<!-- ... later in the document: -->
<p>Teal'c activated his <a href=#gdo><abbr title="Garage Door Opener">GDO</abbr></a>
and so Hammond ordered the iris to be opened.</p>

4.6.9 The abbr element

Status: Implemented and widely deployed

Categories
Flow content.
Phrasing content.
Contexts in which this element may be used:
Where phrasing content is expected.
Content model:
Phrasing content.
Content attributes:
Global attributes
Also, the title attribute has special semantics on this element.
DOM interface:
Uses HTMLElement.

The abbr element represents an abbreviation or acronym, optionally with its expansion. The title attribute may be used to provide an expansion of the abbreviation. The attribute, if specified, must contain an expansion of the abbreviation, and nothing else.

The paragraph below contains an abbreviation marked up with the abbr element. This paragraph defines the term "Web Hypertext Application Technology Working Group".

<p>The <dfn id=whatwg><abbr
title="Web Hypertext Application Technology Working Group">WHATWG</abbr></dfn>
is a loose unofficial collaboration of Web browser manufacturers and
interested parties who wish to develop new technologies designed to
allow authors to write and deploy Applications over the World Wide
Web.</p>

An alternative way to write this would be:

<p>The <dfn id=whatwg>Web Hypertext Application Technology
Working Group</dfn> (<abbr
title="Web Hypertext Application Technology Working Group">WHATWG</abbr>)
is a loose unofficial collaboration of Web browser manufacturers and
interested parties who wish to develop new technologies designed to
allow authors to write and deploy Applications over the World Wide
Web.</p>

This paragraph has two abbreviations. Notice how only one is defined; the other, with no expansion associated with it, does not use the abbr element.

<p>The
<abbr title="Web Hypertext Application Technology Working Group">WHATWG</abbr>
started working on HTML 5 in 2004.</p>

This paragraph links an abbreviation to its definition.

<p>The <a href="#whatwg"><abbr
title="Web Hypertext Application Technology Working Group">WHATWG</abbr></a>
community does not have much representation from Asia.</p>

This paragraph marks up an abbreviation without giving an expansion, possibly as a hook to apply styles for abbreviations (e.g. smallcaps).

<p>Philip` and Dashiva both denied that they were going to
get the issue counts from past revisions of the specification to
backfill the <abbr>WHATWG</abbr> issue graph.</p>

If an abbreviation is pluralized, the expansion's grammatical number (plural vs singular) must match the grammatical number of the contents of the element.

Here the plural is outside the element, so the expansion is in the singular:

<p>Two <abbr title="Working Group">WG</abbr>s worked on
this specification: the <abbr>WHATWG</abbr> and the
<abbr>HTMLWG</abbr>.</p>

Here the plural is inside the element, so the expansion is in the plural:

<p>Two <abbr title="Working Groups">WGs</abbr> worked on
this specification: the <abbr>WHATWG</abbr> and the
<abbr>HTMLWG</abbr>.</p>

Abbreviations do not have to be marked up using this element. It is expected to be useful in the following cases:

Providing an expansion in a title attribute once will not necessarily cause other abbr elements in the same document with the same contents but without a title attribute to behave as if they had the same expansion. Every abbr element is independent.

4.6.10 The time element

Status: Working draft

Categories
Flow content.
Phrasing content.
Contexts in which this element may be used:
Where phrasing content is expected.
Content model:
Phrasing content.
Content attributes:
Global attributes
datetime
DOM interface:
interface HTMLTimeElement : HTMLElement {
           attribute DOMString dateTime;
  readonly attribute Date date;
  readonly attribute Date time;
  readonly attribute Date timezone;
};

The time element represents a precise date and/or a time in the proleptic Gregorian calendar. [GREGORIAN]

This element is intended as a way to encode modern dates and times in a machine-readable way so that user agents can offer to add them to the user's calendar. For example, adding birthday reminders or scheduling events.

The time element is not intended for encoding times for which a precise date or time cannot be established. For example, it would be inappropriate for encoding times like "one millisecond after the big bang", "the early part of the Jurassic period", or "a winter around 250 BCE".

For dates before the introduction of the Gregorian calendar, authors are encouraged to not use the time element, or else to be very careful about converting dates and times from the period to the Gregorian calendar. This is complicated by the manner in which the Gregorian calendar was phased in, which occurred at different times in different countries, ranging from partway through the 16th century all the way to early in the 20th.

The datetime attribute, if present, must contain a valid date or time string that identifies the date or time being specified.

If the datetime attribute is not present, then the date or time must be specified in the content of the element, such that the element's textContent is a valid date or time string in content, and the date, if any, must be expressed using the Gregorian calendar.

If the datetime attribute is present, then the element may be empty, in which case the user agent should convey the attribute's value to the user when rendering the element.

The time element can be used to encode dates, for example in Microformats. The following shows a hypothetical way of encoding an event using a variant on hCalendar that uses the time element:

<div class="vevent">
 <a class="url" href="http://www.web2con.com/">http://www.web2con.com/</a>
  <span class="summary">Web 2.0 Conference</span>:
  <time class="dtstart" datetime="2007-10-05">October 5</time> -
  <time class="dtend" datetime="2007-10-20">19</time>,
  at the <span class="location">Argent Hotel, San Francisco, CA</span>
 </div>

The time element is not necessary for encoding dates or times. In the following snippet, the time is encoded using time, so that it can be restyled (e.g. using XBL2) to match local conventions, while the year is not marked up at all, since marking it up would not be particularly useful.

<p>I usually have a snack at <time>16:00</time>.</p>
<p>I've liked model trains since at least 1983.</p>

Using a styling technology that supports restyling times, the first paragraph from the above snippet could be rendered as follows:

I usually have a snack at 4pm.

Or it could be rendered as follows:

I usually have a snack at 16h00.

time . date

Returns a Date object representing the date component of the element's value, at midnight in the UTC time zone.

Returns null if there is no date.

time . time

Returns a Date object representing the time component of the element's value, on 1970-01-01 in the UTC time zone.

Returns null if there is no time.

time . timezone

Returns a Date object representing the time corresponding to 1970-01-01 00:00 UTC in the time zone given by the element's value.

Returns null if there is no time zone.

The date DOM attribute must return null if the date is unknown, and otherwise must return the time corresponding to midnight UTC (i.e. the first second) of the given date.

The time DOM attribute must return null if the time is unknown, and otherwise must return the time corresponding to the given time of 1970-01-01, with the time zone UTC.

The timezone DOM attribute must return null if the time zone is unknown, and otherwise must return the time corresponding to 1970-01-01 00:00 UTC in the given time zone, with the time zone set to UTC (i.e. the time corresponding to 1970-01-01 at 00:00 UTC plus the offset corresponding to the time zone).

In the following snippet:

<p>Our first date was <time datetime="2006-09-23">a Saturday</time>.</p>

...the time element's date attribute would have the value 1,158,969,600,000ms, and the time and timezone attributes would return null.

In the following snippet:

<p>We stopped talking at <time datetime="2006-09-24T05:00-07:00">5am the next morning</time>.</p>

...the time element's date attribute would have the value 1,159,056,000,000ms, the time attribute would have the value 18,000,000ms, and the timezone attribute would return −25,200,000ms. To obtain the actual time, the three attributes can be added together, obtaining 1,159,048,800,000, which is the specified date and time in UTC.

Finally, in the following snippet:

<p>Many people get up at <time>08:00</time>.</p>

...the time element's date attribute would have the value null, the time attribute would have the value 28,800,000ms, and the timezone attribute would return null.

4.6.11 The progress element

Status: Working draft

Categories
Flow content.
Phrasing content.
Contexts in which this element may be used:
Where phrasing content is expected.
Content model:
Phrasing content.
Content attributes:
Global attributes
value
max
DOM interface:
interface HTMLProgressElement : HTMLElement {
           attribute float value;
           attribute float max;
  readonly attribute float position;
};

The progress element represents the completion progress of a task. The progress is either indeterminate, indicating that progress is being made but that it is not clear how much more work remains to be done before the task is complete (e.g. because the task is waiting for a remote host to respond), or the progress is a number in the range zero to a maximum, giving the fraction of work that has so far been completed.

There are two attributes that determine the current task completion represented by the element.

The value attribute specifies how much of the task has been completed, and the max attribute specifies how much work the task requires in total. The units are arbitrary and not specified.

Instead of using the attributes, authors are recommended to include the current value and the maximum value inline as text inside the element.

Here is a snippet of a Web application that shows the progress of some automated task:

<section>
 <h2>Task Progress</h2>
 <p>Progress: <progress><span id="p">0</span>%</progress></p>
 <script>
  var progressBar = document.getElementById('p');
  function updateProgress(newValue) {
    progressBar.textContent = newValue;
  }
 </script>
</section>

(The updateProgress() method in this example would be called by some other code on the page to update the actual progress bar as the task progressed.)

Author requirementsmax and value attributes, when present, must have values that are valid floating point numbers. The max attribute, if present, must have a value greater than zero. The value attribute, if present, must have a value equal to or greater than zero, and less than or equal to the value of the max attribute, if present, or 1, otherwise.

The progress element is the wrong element to use for something that is just a gauge, as opposed to task progress. For instance, indicating disk space usage using progress would be inappropriate. Instead, the meter element is available for such use cases.

progress . position

For a determinate progress bar (one with known current and maximum values), returns the result of dividing the current value by the maximum value.

For an indeterminate progress bar, returns −1.

If the progress bar is an indeterminate progress bar, then the position DOM attribute must return −1. Otherwise, it must return the result of dividing the current value by the maximum value.

4.6.12 The meter element

Status: Working draft

Categories
Flow content.
Phrasing content.
Contexts in which this element may be used:
Where phrasing content is expected.
Content model:
Phrasing content.
Content attributes:
Global attributes
value
min
low
high
max
optimum
DOM interface:
interface HTMLMeterElement : HTMLElement {
           attribute float value;
           attribute float min;
           attribute float max;
           attribute float low;
           attribute float high;
           attribute float optimum;
};

The meter element represents a scalar measurement within a known range, or a fractional value; for example disk usage, the relevance of a query result, or the fraction of a voting population to have selected a particular candidate.

This is also known as a gauge.

The meter element should not be used to indicate progress (as in a progress bar). For that role, HTML provides a separate progress element.

The meter element also does not represent a scalar value of arbitrary range — for example, it would be wrong to use this to report a weight, or height, unless there is a known maximum value.

There are six attributes that determine the semantics of the gauge represented by the element.

The min attribute specifies the lower bound of the range, and the max attribute specifies the upper bound. The value attribute specifies the value to have the gauge indicate as the "measured" value.

The other three attributes can be used to segment the gauge's range into "low", "medium", and "high" parts, and to indicate which part of the gauge is the "optimum" part. The low attribute specifies the range that is considered to be the "low" part, and the high attribute specifies the range that is considered to be the "high" part. The optimum attribute gives the position that is "optimum"; if that is higher than the "high" value then this indicates that the higher the value, the better; if it's lower than the "low" mark then it indicates that lower values are better, and naturally if it is in between then it indicates that neither high nor low values are good.

Authoring requirements

One of the following conditions, along with all the requirements that are listed with that condition, must be met:

There are exactly two numbers in the contents of the element, and the value, min, and max attributes are all omitted

If specified, the low, high, and optimum attributes must have values greater than or equal to zero and less than or equal to the bigger of the two numbers in the contents of the element.

If both the low and high attributes are specified, then the low attribute's value must be less than or equal to the value of the high attribute.

There is exactly one number followed by zero or more White_Space characters and a valid denominator punctuation character in the contents of the element, and the value, min, and max attributes are all omitted

If specified, the low, high, and optimum attributes must have values greater than or equal to zero and less than or equal to the value associated with the denominator punctuation character.

If both the low and high attributes are specified, then the low attribute's value must be less than or equal to the value of the high attribute.

There is exactly one number in the contents of the element, and the value attribute is omitted
There are no numbers in the contents of the element, and the value attribute is specified

If the min attribute attribute is specified, then the minimum is that attribute's value; otherwise, it is 0.

If the max attribute attribute is specified, then the maximum is that attribute's value; otherwise, it is 1.

If there is exactly one number in the contents of the element, then value is that number; otherwise, value is the value of the value attribute.

The following inequalities must hold, as applicable:

If both the low and high attributes are specified, then the low attribute's value must be less than or equal to the value of the high attribute.

For the purposes of these requirements, a number is a sequence of characters in the range U+0030 DIGIT ZERO (0) to U+0039 DIGIT NINE (9), optionally including with a single U+002E FULL STOP character (.), and separated from other numbers by at least one character that isn't any of those; interpreted as a base ten number.

The value, min, low, high, max, and optimum attributes, when present, must have values that are valid floating point numbers.

If no minimum or maximum is specified, then the range is assumed to be 0..1, and the value thus has to be within that range.

The following examples all represent a measurement of three quarters (of the maximum of whatever is being measured):

<meter>75%</meter>
<meter>750‰</meter>
<meter>3/4</meter>
<meter>6 blocks used (out of 8 total)</meter>
<meter>max: 100; current: 75</meter>
<meter><object data="graph75.png">0.75</object></meter>
<meter min="0" max="100" value="75"></meter>

The following example is incorrect use of the element, because it doesn't give a range (and since the default maximum is 1, both of the gauges would end up looking maxed out):

<p>The grapefruit pie had a radius of <meter>12cm</meter>
and a height of <meter>2cm</meter>.</p> <!-- BAD! -->

Instead, one would either not include the meter element, or use the meter element with a defined range to give the dimensions in context compared to other pies:

<p>The grapefruit pie had a radius of 12cm and a height of
2cm.</p>
<dl>
 <dt>Radius: <dd> <meter min=0 max=20 value=12>12cm</meter>
 <dt>Height: <dd> <meter min=0 max=10 value=2>2cm</meter>
</dl>

There is no explicit way to specify units in the meter element, but the units may be specified in the title attribute in free-form text.

The example above could be extended to mention the units:

<dl>
 <dt>Radius: <dd> <meter min=0 max=20 value=12 title="centimeters">12cm</meter>
 <dt>Height: <dd> <meter min=0 max=10 value=2 title="centimeters">2cm</meter>
</dl>

4.6.13 The code element

Status: Implemented and widely deployed

Categories
Flow content.
Phrasing content.
Contexts in which this element may be used:
Where phrasing content is expected.
Content model:
Phrasing content.
Content attributes:
Global attributes
DOM interface:
Uses HTMLElement.

The code element represents a fragment of computer code. This could be an XML element name, a filename, a computer program, or any other string that a computer would recognize.

Although there is no formal way to indicate the language of computer code being marked up, authors who wish to mark code elements with the language used, e.g. so that syntax highlighting scripts can use the right rules, may do so by adding a class prefixed with "language-" to the element.

The following example shows how the element can be used in a paragraph to mark up element names and computer code, including punctuation.

<p>The <code>code</code> element represents a fragment of computer
code.</p>

<p>When you call the <code>activate()</code> method on the
<code>robotSnowman</code> object, the eyes glow.</p>

<p>The example below uses the <code>begin</code> keyword to indicate
the start of a statement block. It is paired with an <code>end</code>
keyword, which is followed by the <code>.</code> punctuation character
(full stop) to indicate the end of the program.</p>

The following example shows how a block of code could be marked up using the pre and code elements.

<pre><code class="language-pascal">var i: Integer;
begin
   i := 1;
end.</code></pre>

A class is used in that example to indicate the language used.

See the pre element for more details.

4.6.14 The var element

Status: Implemented and widely deployed

Categories
Flow content.
Phrasing content.
Contexts in which this element may be used:
Where phrasing content is expected.
Content model:
Phrasing content.
Content attributes:
Global attributes
DOM interface:
Uses HTMLElement.

The var element represents a variable. This could be an actual variable in a mathematical expression or programming context, or it could just be a term used as a placeholder in prose.

In the paragraph below, the letter "n" is being used as a variable in prose:

<p>If there are <var>n</var> pipes leading to the ice
cream factory then I expect at <em>least</em> <var>n</var>
flavors of ice cream to be available for purchase!</p>

For mathematics, in particular for anything beyond the simplest of expressions, MathML is more appropriate. However, the var element can still be used to refer to specific variables that are then mentioned in MathML expressions.

In this example, an equation is shown, with a legend that references the variables in the equation. The expression itself is marked up with MathML, but the variables are mentioned in the figure's legend using var.

<figure>
 <math>
  <mi>a</mi>
  <mo>=</mo>
  <msqrt>
   <msup><mi>b</mi><mn>2</mn></msup>
   <mi>+</mi>
   <msup><mi>c</mi><mn>2</mn></msup>
  </msqrt>
 </math>
 <legend>
  Using Pythagoras' theorem to solve for the hypotenuse <var>a</var> of
  a triangle with sides <var>b</var> and <var>c</var>
 </legend>
</figure>

4.6.15 The samp element

Status: Implemented and widely deployed

Categories
Flow content.
Phrasing content.
Contexts in which this element may be used:
Where phrasing content is expected.
Content model:
Phrasing content.
Content attributes:
Global attributes
DOM interface:
Uses HTMLElement.

The samp element represents (sample) output from a program or computing system.

See the pre and kbd elements for more details.

This example shows the samp element being used inline:

<p>The computer said <samp>Too much cheese in tray
two</samp> but I didn't know what that meant.</p>

This second example shows a block of sample output. Nested samp and kbd elements allow for the styling of specific elements of the sample output using a style sheet.

<pre><samp><span class="prompt">jdoe@mowmow:~$</span> <kbd>ssh demo.example.com</kbd>
Last login: Tue Apr 12 09:10:17 2005 from mowmow.example.com on pts/1
Linux demo 2.6.10-grsec+gg3+e+fhs6b+nfs+gr0501+++p3+c4a+gr2b-reslog-v6.189 #1 SMP Tue Feb 1 11:22:36 PST 2005 i686 unknown

<span class="prompt">jdoe@demo:~$</span> <span class="cursor">_</span></samp></pre>

4.6.16 The kbd element

Status: Implemented and widely deployed

Categories
Flow content.
Phrasing content.
Contexts in which this element may be used:
Where phrasing content is expected.
Content model:
Phrasing content.
Content attributes:
Global attributes
DOM interface:
Uses HTMLElement.

The kbd element represents user input (typically keyboard input, although it may also be used to represent other input, such as voice commands).

When the kbd element is nested inside a samp element, it represents the input as it was echoed by the system.

When the kbd element contains a samp element, it represents input based on system output, for example invoking a menu item.

When the kbd element is nested inside another kbd element, it represents an actual key or other single unit of input as appropriate for the input mechanism.

Here the kbd element is used to indicate keys to press:

<p>To make George eat an apple, press <kbd><kbd>Shift</kbd>+<kbd>F3</kbd></kbd></p>

In this second example, the user is told to pick a particular menu item. The outer kbd element marks up a block of input, with the inner kbd elements representing each individual step of the input, and the samp elements inside them indicating that the steps are input based on something being displayed by the system, in this case menu labels:

<p>To make George eat an apple, select
    <kbd><kbd><samp>File</samp></kbd>|<kbd><samp>Eat Apple...</samp></kbd></kbd>
</p>

4.6.17 The sub and sup elements

Status: Implemented and widely deployed

Categories
Flow content.
Phrasing content.
Contexts in which these elements may be used:
Where phrasing content is expected.
Content model:
Phrasing content.
Content attributes:
Global attributes
DOM interface:
Uses HTMLElement.

The sup element represents a superscript and the sub element represents a subscript.

These elements must be used only to mark up typographical conventions with specific meanings, not for typographical presentation for presentation's sake. For example, it would be inappropriate for the sub and sup elements to be used in the name of the LaTeX document preparation system. In general, authors should use these elements only if the absence of those elements would change the meaning of the content.

When the sub element is used inside a var element, it represents the subscript that identifies the variable in a family of variables.

<p>The coordinate of the <var>i</var>th point is
(<var>x<sub><var>i</var></sub></var>, <var>y<sub><var>i</var></sub></var>).
For example, the 10th point has coordinate
(<var>x<sub>10</sub></var>, <var>y<sub>10</sub></var>).</p>

In certain languages, superscripts are part of the typographical conventions for some abbreviations.

<p>The most beautiful women are
<span lang="fr"><abbr>M<sup>lle</sup></abbr> Gwendoline</span> and
<span lang="fr"><abbr>M<sup>me</sup></abbr> Denise</span>.</p>

Mathematical expressions often use subscripts and superscripts. Authors are encouraged to use MathML for marking up mathematics, but authors may opt to use sub and sup if detailed mathematical markup is not desired. [MATHML]

<var>E</var>=<var>m</var><var>c</var><sup>2</sup>
f(<var>x</var>, <var>n</var>) = log<sub>4</sub><var>x</var><sup><var>n</var></sup>

4.6.18 The span element

Status: Implemented and widely deployed

Categories
Flow content.
Phrasing content.
Contexts in which this element may be used:
Where phrasing content is expected.
Content model:
Phrasing content.
Content attributes:
Global attributes
DOM interface:
interface HTMLSpanElement : HTMLElement {};

The span element doesn't mean anything on its own, but can be useful when used together with other attributes, e.g. class, lang, or dir. It represents its children.

4.6.19 The i element

Status: Implemented and widely deployed

Categories
Flow content.
Phrasing content.
Contexts in which this element may be used:
Where phrasing content is expected.
Content model:
Phrasing content.
Content attributes:
Global attributes
DOM interface:
Uses HTMLElement.

The i element represents a span of text in an alternate voice or mood, or otherwise offset from the normal prose, such as a taxonomic designation, a technical term, an idiomatic phrase from another language, a thought, a ship name, or some other prose whose typical typographic presentation is italicized.

Terms in languages different from the main text should be annotated with lang attributes (or, in XML, lang attributes in the XML namespace).

The examples below show uses of the i element:

<p>The <i class="taxonomy">Felis silvestris catus</i> is cute.</p>
<p>The term <i>prose content</i> is defined above.</p>
<p>There is a certain <i lang="fr">je ne sais quoi</i> in the air.</p>

In the following example, a dream sequence is marked up using i elements.

<p>Raymond tried to sleep.</p>
<p><i>The ship sailed away on Thursday</i>, he
dreamt. <i>The ship had many people aboard, including a beautiful
princess called Carey. He watched her, day-in, day-out, hoping she
would notice him, but she never did.</i></p>
<p><i>Finally one night he picked up the courage to speak with
her—</i></p>
<p>Raymond woke with a start as the fire alarm rang out.</p>

Authors are encouraged to use the class attribute on the i element to identify why the element is being used, so that if the style of a particular use (e.g. dream sequences as opposed to taxonomic terms) is to be changed at a later date, the author doesn't have to go through the entire document (or series of related documents) annotating each use. Similarly, authors are encouraged to consider whether other elements might be more applicable than the i element, for instance the em element for marking up stress emphasis, or the dfn element to mark up the defining instance of a term.

Style sheets can be used to format i elements, just like any other element can be restyled. Thus, it is not the case that content in i elements will necessarily be italicized.

4.6.20 The b element

Status: Implemented and widely deployed

Categories
Flow content.
Phrasing content.
Contexts in which this element may be used:
Where phrasing content is expected.
Content model:
Phrasing content.
Content attributes:
Global attributes
DOM interface:
Uses HTMLElement.

The b element represents a span of text to be stylistically offset from the normal prose without conveying any extra importance, such as key words in a document abstract, product names in a review, or other spans of text whose typical typographic presentation is boldened.

The following example shows a use of the b element to highlight key words without marking them up as important:

<p>The <b>frobonitor</b> and <b>barbinator</b> components are fried.</p>

In the following example, objects in a text adventure are highlighted as being special by use of the b element.

<p>You enter a small room. Your <b>sword</b> glows
brighter. A <b>rat</b> scurries past the corner wall.</p>

Another case where the b element is appropriate is in marking up the lede (or lead) sentence or paragraph. The following example shows how a BBC article about kittens adopting a rabbit as their own could be marked up:

<article>
 <h2>Kittens 'adopted' by pet rabbit</h2>
 <p><b>Six abandoned kittens have found an unexpected new
 mother figure — a pet rabbit.</b></p>
 <p>Veterinary nurse Melanie Humble took the three-week-old
 kittens to her Aberdeen home.</p>
[...]

The b element should be used as a last resort when no other element is more appropriate. In particular, headings should use the h1 to h6 elements, stress emphasis should use the em element, importance should be denoted with the strong element, and text marked or highlighted should use the mark element.

The following would be incorrect usage:

<p><b>WARNING!</b> Do not frob the barbinator!</p>

In the previous example, the correct element to use would have been strong, not b.

Style sheets can be used to format b elements, just like any other element can be restyled. Thus, it is not the case that content in b elements will necessarily be boldened.

4.6.21 The bdo element

Status: Implemented and widely deployed

Categories
Flow content.
Phrasing content.
Contexts in which this element may be used:
Where phrasing content is expected.
Content model:
Phrasing content.
Content attributes:
Global attributes
Also, the dir global attribute has special semantics on this element.
DOM interface:
Uses HTMLElement.

The bdo element represents explicit text directionality formatting control for its children. It allows authors to override the Unicode bidi algorithm by explicitly specifying a direction override. [BIDI]

Authors must specify the dir attribute on this element, with the value ltr to specify a left-to-right override and with the value rtl to specify a right-to-left override.

4.6.22 The ruby element

Status: Working draft

Categories
Flow content.
Phrasing content.
Contexts in which this element may be used:
Where phrasing content is expected.
Content model:
One or more groups of: phrasing content followed either by a single rt element, or an rp element, an rt element, and another rp element.
Content attributes:
Global attributes
DOM interface:
Uses HTMLElement.

The ruby element allows one or more spans of phrasing content to be marked with ruby annotations. Ruby annotations are short runs of text presented alongside base text, primarily used in East Asian typography as a guide for pronunciation or to include other annotations. In Japanese, this form of typography is also known as furigana.

A ruby element represents the spans of phrasing content it contains, ignoring all the child rt and rp elements and their descendants. Those spans of phrasing content have associated annotations created using the rt element.

In this example, each ideograph in the Japanese text 漢字 is annotated with its kanji reading.

...
<ruby>
 漢 <rt> かん </rt>
 字 <rt> じ  </rt>
</ruby>
...

This might be rendered as:

The two main ideographs, each with its kanji annotation rendered in a smaller font above it.

In this example, each ideograph in the traditional Chinese text 漢字 is annotated with its bopomofo reading.

<ruby>
 漢 <rt> ㄏㄢˋ </rt>
 字 <rt> ㄗˋ  </rt>
</ruby>

This might be rendered as:

The two main ideographs, each with its bopomofo annotation rendered in a smaller font next to it.

In this example, each ideograph in the simplified Chinese text 汉字 is annotated with its pinyin reading.

...
<ruby>
 汉 <rt> hàn </rt>
 å­— <rt> zì  </rt>
</ruby>
...

This might be rendered as:

The two main ideographs, each with its pinyin annotation rendered in a smaller font above it.

4.6.23 The rt element

Status: Working draft

Categories
None.
Contexts in which this element may be used:
As a child of a ruby element.
Content model:
Phrasing content.
Content attributes:
Global attributes
DOM interface:
Uses HTMLElement.

The rt element marks the ruby text component of a ruby annotation.

An rt element represents an annotation (given by its children) for the zero or more nodes of phrasing content that immediately precedes it in the ruby element, ignoring rp elements.

4.6.24 The rp element

Status: Working draft

Categories
None.
Contexts in which this element may be used:
As a child of a ruby element, either immediately before or immediately after an rt element.
Content model:
Phrasing content.
Content attributes:
Global attributes
DOM interface:
Uses HTMLElement.

The rp element can be used to provide parentheses around a ruby text component of a ruby annotation, to be shown by user agents that don't support ruby annotations.

An rp element represents nothing.

The example above, in which each ideograph in the text 漢字 is annotated with its kanji reading, could be expanded to use rp so that in legacy user agents the readings are in parentheses:

...
<ruby>
 漢 <rp>(</rp><rt>かん</rt><rp>)</rp>
 字 <rp>(</rp><rt>じ</rt><rp>)</rp>
</ruby>
...

In conforming user agents the rendering would be as above, but in user agents that do not support ruby, the rendering would be:

... 漢 (かん) 字 (じ) ...

4.6.25 Usage summary

We need to summarize the various elements, in particular to distinguish b/i/em/strong/var/q/mark/cite.

4.6.26 Footnotes

HTML does not have a dedicated mechanism for marking up footnotes. Here are the recommended alternatives.

For short inline annotations, the title attribute should be used.

In this example, two parts of a dialog are annotated.

<dialog>
 <dt>Customer
 <dd>Hello! I wish to register a complaint. Hello. Miss?
 <dt>Shopkeeper
 <dd><span title="Colloquial pronunciation of 'What do you'"
 >Watcha</span> mean, miss?
 <dt>Customer
 <dd>Uh, I'm sorry, I have a cold. I wish to make a complaint.
 <dt>Shopkeeper
 <dd>Sorry, <span title="This is, of course, a lie.">we're
 closing for lunch</span>.
</dialog>

For longer annotations, the a element should be used, pointing to an element later in the document. The convention is that the contents of the link be a number in square brackets.

In this example, a footnote in the dialog links to a paragraph below the dialog. The paragraph then reciprocally links back to the dialog, allowing the user to return to the location of the footnote.

<dialog>
 <dt>Announcer
 <dd>Number 16: The <i>hand</i>.
 <dt>Interviewer
 <dd>Good evening. I have with me in the studio tonight Mr
 Norman St John Polevaulter, who for the past few years has
 been contradicting people. Mr Polevaulter, why <em>do</em>
 you contradict people?
 <dt>Norman
 <dd>I don't. <a href="#fn1" id="r1">[1]</a>
 <dt>Interviewer
 <dd>You told me you did!
</dialog>
<section>
 <p id="fn1"><a href="#r1">[1]</a> This is, naturally, a lie,
 but paradoxically if it were true he could not say so without
 contradicting the interviewer and thus making it false.</p>
</section>

For side notes, longer annotations that apply to entire sections of the text rather than just specific words or sentences, the aside element should be used.

In this example, a sidebar is given after a dialog, giving some context to the dialog.

<dialog>
 <dt>Customer
 <dd>I will not buy this record, it is scratched.
 <dt>Shopkeeper
 <dd>I'm sorry?
 <dt>Customer
 <dd>I will not buy this record, it is scratched.
 <dt>Shopkeeper
 <dd>No no no, this's'a tobacconist's.
</dialog>
<aside>
 <p>In 1970, the British Empire lay in ruins, and foreign
 nationalists frequented the streets — many of them Hungarians
 (not the streets — the foreign nationals). Sadly, Alexander
 Yalt has been publishing incompetently-written phrase books.
</aside>

For figures or tables, footnotes can be included in the relevant legend or caption element, or in surrounding prose.

In this example, a table has cells with footnotes that are given in prose. A figure element is used to give a single legend to the combination of the table and its footnotes.

<figure>
 <legend>Table 1. Alternative activities for knights.</legend>
 <table>
  <tr>
   <th> Activity
   <th> Location
   <th> Cost
  <tr>
   <td> Dance
   <td> Wherever possible
   <td> £0<sup><a href="#fn1">1</a></sup>
  <tr>
   <td> Routines, chorus scenes<sup><a href="#fn2">2</a></sup>
   <td> Undisclosed
   <td> Undisclosed
  <tr>
   <td> Dining<sup><a href="#fn3">3</a></sup>
   <td> Camelot
   <td> Cost of ham, jam, and spam<sup><a href="#fn4">4</a></sup>
 </table>
 <p id="fn1">1. Assumed.</p>
 <p id="fn2">2. Footwork impeccable.</p>
 <p id="fn3">3. Quality described as "well".</p>
 <p id="fn4">4. A lot.</p>
</figure>

4.7 Edits

The ins and del elements represent edits to the document.

4.7.1 The ins element

Status: Implemented and widely deployed

Categories
Flow content.
When the element only contains phrasing content: phrasing content.
Contexts in which this element may be used:
Where phrasing content is expected.
Content model:
Transparent.
Content attributes:
Global attributes
cite
datetime
DOM interface:
Uses the HTMLModElement interface.

The ins element represents an addition to the document.

The following represents the addition of a single paragraph:

<aside>
 <ins>
  <p> I like fruit. </p>
 </ins>
</aside>

As does this, because everything in the aside element here counts as phrasing content and therefore there is just one paragraph:

<aside>
 <ins>
  Apples are <em>tasty</em>.
 </ins>
 <ins>
  So are pears.
 </ins>
</aside>

ins elements should not cross implied paragraph boundaries.

The following example represents the addition of two paragraphs, the second of which was inserted in two parts. The first ins element in this example thus crosses a paragraph boundary, which is considered poor form.

<aside>
 <ins datetime="2005-03-16T00:00Z">
  <p> I like fruit. </p>
  Apples are <em>tasty</em>.
 </ins>
 <ins datetime="2007-12-19T00:00Z">
  So are pears.
 </ins>
</aside>

Here is a better way of marking this up. It uses more elements, but none of the elements cross implied paragraph boundaries.

<aside>
 <ins datetime="2005-03-16T00:00Z">
  <p> I like fruit. </p>
 </ins>
 <ins datetime="2005-03-16T00:00Z">
  Apples are <em>tasty</em>.
 </ins>
 <ins datetime="2007-12-19T00:00Z">
  So are pears.
 </ins>
</aside>

4.7.2 The del element

Status: Implemented and widely deployed

Categories
Flow content.
When the element only contains phrasing content: phrasing content.
Contexts in which this element may be used:
Where phrasing content is expected.
Content model:
Transparent.
Content attributes:
Global attributes
cite
datetime
DOM interface:
Uses the HTMLModElement interface.

The del element represents a removal from the document.

del elements should not cross implied paragraph boundaries.

4.7.3 Attributes common to ins and del elements

The cite attribute may be used to specify the address of a document that explains the change. When that document is long, for instance the minutes of a meeting, authors are encouraged to include a fragment identifier pointing to the specific part of that document that discusses the change.

If the cite attribute is present, it must be a valid URL that explains the change.

The datetime attribute may be used to specify the time and date of the change.

If present, the datetime attribute must be a valid global date and time string value.

The ins and del elements implement the HTMLModElement interface:

interface HTMLModElement : HTMLElement {
           attribute DOMString cite;
           attribute DOMString dateTime;
};

4.7.4 Edits and paragraphs

Since the ins and del elements do not affect paragraphing, it is possible, in some cases where paragraphs are implied (without explicit p elements), for an ins or del element to span both an entire paragraph or other non-phrasing content elements and part of another paragraph.

For example:

<section>
 <ins>
  <p>
   This is a paragraph that was inserted.
  </p>
  This is another paragraph whose first sentence was inserted
  at the same time as the paragraph above.
 </ins>
 This is a second sentence, which was there all along.
</section>

By only wrapping some paragraphs in p elements, one can even get the end of one paragraph, a whole second paragraph, and the start of a third paragraph to be covered by the same ins or del element (though this is very confusing, and not considered good practice):

<section>
 This is the first paragraph. <ins>This sentence was
 inserted.
 <p>This second paragraph was inserted.</p>
 This sentence was inserted too.</ins> This is the
 third paragraph in this example.
</section>

However, due to the way implied paragraphs are defined, it is not possible to mark up the end of one paragraph and the start of the very next one using the same ins or del element. You instead have to use one (or two) p element(s) and two ins or del elements:

For example:

<section>
 <p>This is the first paragraph. <del>This sentence was
 deleted.</del></p>
 <p><del>This sentence was deleted too.</del> That
 sentence needed a separate &lt;del&gt; element.</p>
</section>

Partly because of the confusion described above, authors are strongly recommended to always mark up all paragraphs with the p element, and to not have any ins or del elements that cross across any implied paragraphs.

4.7.5 Edits and lists

The content models of the ol and ul elements do not allow ins and del elements as children. Lists always represent all their items, including items that would otherwise have been marked as deleted.

To indicate that an item is inserted or deleted, an ins or del element can be wrapped around the contents of the li element. To indicate that an item has been replaced by another, a single li element can have one or more del elements followed by one or more ins elements.

In the following example, a list that started empty had items added and removed from it over time. The bits in the example that have been emphasized show the parts that are the "current" state of the list. The list item numbers don't take into account the edits, though.

<h1>Stop-ship bugs</h1>
<ol>
 <li><ins datetime="2008-02-12T15:20Z">Bug 225:
 Rain detector doesn't work in snow</ins></li>
 <li><del datetime="2008-03-01T20:22Z"><ins datetime="2008-02-14T12:02Z">Bug 228:
 Water buffer overflows in April</ins></del></li>
 <li><ins datetime="2008-02-16T13:50Z">Bug 230:
 Water heater doesn't use renewable fuels</ins></li>
 <li><del datetime="2008-02-20T21:15Z"><ins datetime="2008-02-16T14:25Z">Bug 232:
 Carbon dioxide emissions detected after startup</ins></del></li>
</ol>

In the following example, a list that started with just fruit was replaced by a list with just colors.

<h1>List of <del>fruits</del><ins>colors</ins></h1>
<ul>
 <li><del>Lime</del><ins>Green</ins></li>
 <li><del>Apple</del></li>
 <li>Orange</li>
 <li><del>Pear</del></li>
 <li><ins>Teal</ins></li>
 <li><del>Lemon</del><ins>Yellow</ins></li>
 <li>Olive</li>
 <li><ins>Purple</ins>
</ul>

4.8 Embedded content

4.8.1 The figure element

Status: Working draft

Categories
Flow content.
Sectioning root.
Contexts in which this element may be used:
Where flow content is expected.
Content model:
Either: one legend element followed by flow content.
Or: Flow content followed by one legend element.
Or: Flow content.
Content attributes:
Global attributes
DOM interface:
Uses HTMLElement.

The figure element represents some flow content, optionally with a caption, that is self-contained and is typically referenced as a single unit from the main flow of the document.

The element can thus be used to annotate illustrations, diagrams, photos, code listings, etc, that are referred to from the main content of the document, but that could, without affecting the flow of the document, be moved away from that primary content, e.g. to the side of the page, to dedicated pages, or to an appendix.

The first legend element child of the element, if any, represents the caption of the figure element's contents. If there is no child legend element, then there is no caption.

The remainder of the element's contents, if any, represents the content.

This example shows the figure element to mark up a code listing.

<p>In <a href="#l4">listing 4</a> we see the primary core interface
API declaration.</p>
<figure id="l4">
 <legend>Listing 4. The primary core interface API declaration.</legend>
 <pre><code>interface PrimaryCore {
  boolean verifyDataLine();
  void sendData(in sequence&lt;byte> data);
  void initSelfDestruct();
}</code></pre>
</figure>
<p>The API is designed to use UTF-8.</p>

Here we see a figure element to mark up a photo.

<figure>
 <img src="bubbles-work.jpeg"
      alt="Bubbles, sitting in his office chair, works on his
           latest project intently.">
 <legend>Bubbles at work</legend>
</figure>

In this example, we see an image that is not a figure, as well as an image and a video that are.

<h2>Malinko's comics</h2>

<p>This case centered on some sort of "intellectual property"
infringement related to a comic (see Exhibit A). The suit started
after a trailer ending with these words:</p>

<img src="promblem-packed-action.png" alt="ROUGH COPY! Promblem-Packed Action!">

<p>...was aired. A lawyer, armed with a Bigger Notebook, launched a
preemptive strike using snowballs. A complete copy of the trailer is
included with Exhibit B.</p>

<figure>
 <img src="ex-a.png" alt="Two squiggles on a dirty piece of paper.">
 <legend>Exhibit A. The alleged <cite>rough copy</cite> comic.</legend>
</figure>

<figure>
 <video src="ex-b.mov"></video>
 <legend>Exhibit B. The <code>Rough Copy</cite> trailer.</legend>
</figure>

<p>The case was resolved out of court.</p>

Here, a part of a poem is marked up using figure.

<figure>
 <p>'Twas brillig, and the slithy toves<br>
Did gyre and gimble in the wabe;<br>
All mimsy were the borogoves,<br>
And the mome raths outgrabe.</p>
 <legend><cite>Jabberwocky</cite> (first verse). Lewis Carroll, 1832-98</legend>
</figure>

In this example, which could be part of a much larger work discussing a castle, the figure has three images in it.

<figure>
 <img src="castle1423.jpeg" title="Etching. Anonymous, ca. 1423."
      alt="The castle has one tower, and a tall wall around it.">
 <img src="castle1858.jpeg" title="Oil-based paint on canvas. Maria Towle, 1858."
      alt="The castle now has two towers and two walls.">
 <img src="castle1999.jpeg" title="Film photograph. Peter Jankle, 1999."
      alt="The castle lies in ruins, the original tower all that remains in one piece.">
 <legend>The castle through the ages: 1423, 1858, and 1999 respectively.</legend>
</figure>

4.8.2 The img element

Status: Last call for comments

Categories
Flow content.
Phrasing content.
Embedded content.
If the element has a usemap attribute: Interactive content.
Contexts in which this element may be used:
Where embedded content is expected.
Content model:
Empty.
Content attributes:
Global attributes
alt
src
usemap
ismap
width
height
DOM interface:
[NamedConstructor=Image(),
 NamedConstructor=Image(in unsigned long width),
 NamedConstructor=Image(in unsigned long width, in unsigned long height)]
interface HTMLImageElement : HTMLElement {
           attribute DOMString alt;
           attribute DOMString src;
           attribute DOMString useMap;
           attribute boolean isMap;
           attribute unsigned long width;
           attribute unsigned long height;
  readonly attribute boolean complete;
};

An img element represents an image.

The image given by the src attribute is the embedded content, and the value of the alt attribute is the img element's fallback content.

The src attribute must be present, and must contain a valid URL referencing a non-interactive, optionally animated, image resource that is neither paged nor scripted. If the base URI of the element is the same as the document's address, then the src attribute's value must not be the empty string.

Images can thus be static bitmaps (e.g. PNGs, GIFs, JPEGs), single-page vector documents (single-page PDFs, XML files with an SVG root element), animated bitmaps (APNGs, animated GIFs), animated vector graphics (XML files with an SVG root element that use declarative SMIL animation), and so forth. However, this also precludes SVG files with script, multipage PDF files, interactive MNG files, HTML documents, plain text documents, and so forth.

The requirements on the alt attribute's value are described in the next section.

The img must not be used as a layout tool. In particular, img elements should not be used to display transparent images, as they rarely convey meaning and rarely add anything useful to the document.


The usemap attribute, if present, can indicate that the image has an associated image map.

The ismap attribute, when used on an element that is a descendant of an a element with an href attribute, indicates by its presence that the element provides access to a server-side image map. This affects how events are handled on the corresponding a element.

The ismap attribute is a boolean attribute. The attribute must not be specified on an element that does not have an ancestor a element with an href attribute.

The img element supports dimension attributes.

image . width [ = value ]
image . height [ = value ]

These attributes return the actual rendered dimensions of the image, or zero if the dimensions are not known.

They can be set, to change the corresponding content attributes.

image . complete

Returns true if the image has been downloaded, decoded, and found to be valid; otherwise, returns false.

image = new Image( [ width [, height ] ] )

Returns a new img element, with the width and height attributes set to the values passed in the relevant arguments, if applicable.

A single image can have different appropriate alternative text depending on the context.

In each of the following cases, the same image is used, yet the alt text is different each time. The image is the coat of arms of the Canton Geneva in Switzerland.

Here it is used as a supplementary icon:

<p>I lived in <img src="carouge.svg" alt=""> Carouge.</p>

Here it is used as an icon representing the town:

<p>Home town: <img src="carouge.svg" alt="Carouge"></p>

Here it is used as part of a text on the town:

<p>Carouge has a coat of arms.</p>
<p><img src="carouge.svg" alt="The coat of arms depicts a lion, sitting in front of a tree."></p>
<p>It is used as decoration all over the town.</p>

Here it is used as a way to support a similar text where the description is given as well as, instead of as an alternative to, the image:

<p>Carouge has a coat of arms.</p>
<p><img src="carouge.svg" alt=""></p>
<p>The coat of arms depicts a lion, sitting in front of a tree.
It is used as decoration all over the town.</p>

Here it is used as part of a story:

<p>He picked up the folder and a piece of paper fell out.</p>
<p><img src="carouge.svg" alt="Shaped like a shield, the paper had a
red background, a green tree, and a yellow lion with its tongue
hanging out and whose tail was shaped like an S."></p>
<p>He stared at the folder. S! The answer he had been looking for all
this time was simply the letter S! How had he not seen that before? It all
came together now. The phone call where Hector had referred to a lion's tail,
the time Marco had stuck his tongue out...</p>

Here it is not known at the time of publication what the image will be, only that it will be a coat of arms of some kind, and thus no replacement text can be provided, and instead only a brief caption for the image is provided, in the title attribute:

<p>The last user to have uploaded a coat of arms uploaded this one:</p>
<p><img src="last-uploaded-coat-of-arms.cgi" title="User-uploaded coat of arms."></p>

Ideally, the author would find a way to provide real replacement text even in this case, e.g. by asking the previous user. Not providing replacement text makes the document more difficult to use for people who are unable to view images, e.g. blind users, or users or very low-bandwidth connections or who pay by the byte, or users who are forced to use a text-only Web browser.

Here are some more examples showing the same picture used in different contexts, with different appropriate alternate texts each time.

<article>
 <h1>My cats</h1>
 <h2>Fluffy</h2>
 <p>Fluffy is my favorite.</p>
 <img src="fluffy.jpg" alt="She likes playing with a ball of yarn.">
 <p>She's just too cute.</p>
 <h2>Miles</h2>
 <p>My other cat, Miles just eats and sleeps.</p>
</article>
<article>
 <h1>Photography</h1>
 <h2>Shooting moving targets indoors</h2>
 <p>The trick here is to know how to anticipate; to know at what speed and
 what distance the subject will pass by.</p>
 <img src="fluffy.jpg" alt="A cat flying by, chasing a ball of yarn, can be
 photographed quite nicely using this technique.">
 <h2>Nature by night</h2>
 <p>To achieve this, you'll need either an extremely sensitive film, or
 immense flash lights.</p>
</article>
<article>
 <h1>About me</h1>
 <h2>My pets</h2>
 <p>I've got a cat named Fluffy and a dog named Miles.</p>
 <img src="fluffy.jpg" alt="Fluffy, my cat, tends to keep itself busy.">
 <p>My dog Miles and I like go on long walks together.</p>
 <h2>music</h2>
 <p>After our walks, having emptied my mind, I like listening to Bach.</p>
</article>
<article>
 <h1>Fluffy and the Yarn</h1>
 <p>Fluffy was a cat who liked to play with yarn. He also liked to jump.</p>
 <aside><img src="fluffy.jpg" alt="" title="Fluffy"></aside>
 <p>He would play in the morning, he would play in the evening.</p>
</article>
4.8.2.1 Requirements for providing text to act as an alternative for images

Status: Controversial Working Draft

The requirements for the alt attribute depend on what the image is intended to represent, as described in the following sections.

When an a element that is a hyperlink, or a button element, has no textual content but contains one or more images, the alt attributes must contain text that together convey the purpose of the link or button.

In this example, a user is asked to pick his preferred color from a list of three. Each color is given by an image, but for users who have configured their user agent not to display images, the color names are used instead:

<h1>Pick your color</h1>
<ul>
 <li><a href="green.html"><img src="green.jpeg" alt="Green"></a></li>
 <li><a href="blue.html"><img src="blue.jpeg" alt="Blue"></a></li>
 <li><a href="red.html"><img src="red.jpeg" alt="Red"></a></li>
</ul>

In this example, each button has a set of images to indicate the kind of color output desired by the user. The first image is used in each case to give the alternative text.

<button name="rgb"><img src="red" alt="RGB"><img src="green" alt=""><img src="blue" alt=""></button>
<button name="cmyk"><img src="cyan" alt="CMYK"><img src="magenta" alt=""><img src="yellow" alt=""><img src="black" alt=""></button>

Since each image represents one part of the text, it could also be written like this:

<button name="rgb"><img src="red" alt="R"><img src="green" alt="G"><img src="blue" alt="B"></button>
<button name="cmyk"><img src="cyan" alt="C"><img src="magenta" alt="M"><img src="yellow" alt="Y"><img src="black" alt="K"></button>

However, with other alternative text, this might not work, and putting all the alternative text into one image in each case might make more sense:

<button name="rgb"><img src="red" alt="sRGB profile"><img src="green" alt=""><img src="blue" alt=""></button>
<button name="cmyk"><img src="cyan" alt="CMYK profile"><img src="magenta" alt=""><img src="yellow" alt=""><img src="black" alt=""></button>
4.8.2.1.2 A phrase or paragraph with an alternative graphical representation: charts, diagrams, graphs, maps, illustrations

Sometimes something can be more clearly stated in graphical form, for example as a flowchart, a diagram, a graph, or a simple map showing directions. In such cases, an image can be given using the img element, but the lesser textual version must still be given, so that users who are unable to view the image (e.g. because they have a very slow connection, or because they are using a text-only browser, or because they are listening to the page being read out by a hands-free automobile voice Web browser, or simply because they are blind) are still able to understand the message being conveyed.

The text must be given in the alt attribute, and must convey the same message as the image specified in the src attribute.

It is important to realize that the alternative text is a replacement for the image, not a description of the image.

In the following example we have a flowchart in image form, with text in the alt attribute rephrasing the flowchart in prose form:

<p>In the common case, the data handled by the tokenization stage
comes from the network, but it can also come from script.</p>
<p><img src="images/parsing-model-overview.png" alt="The network
passes data to the Tokenizer stage, which passes data to the Tree
Construction stage. From there, data goes to both the DOM and to
Script Execution. Script Execution is linked to the DOM, and, using
document.write(), passes data to the Tokenizer."></p>

Here's another example, showing a good solution and a bad solution to the problem of including an image in a description.

First, here's the good solution. This sample shows how the alternative text should just be what you would have put in the prose if the image had never existed.

<!-- This is the correct way to do things. -->
<p>
 You are standing in an open field west of a house.
 <img src="house.jpeg" alt="The house is white, with a boarded front door.">
 There is a small mailbox here.
</p>

Second, here's the bad solution. In this incorrect way of doing things, the alternative text is simply a description of the image, instead of a textual replacement for the image. It's bad because when the image isn't shown, the text doesn't flow as well as in the first example.

<!-- This is the wrong way to do things. -->
<p>
 You are standing in an open field west of a house.
 <img src="house.jpeg" alt="A white house, with a boarded front door.">
 There is a small mailbox here.
</p>

Text such as "Photo of white house with boarded door" would be equally bad alternative text (though it could be suitable for the title attribute or in the legend element of a figure with this image).

4.8.2.1.3 A short phrase or label with an alternative graphical representation: icons, logos

A document can contain information in iconic form. The icon is intended to help users of visual browsers to recognize features at a glance.

In some cases, the icon is supplemental to a text label conveying the same meaning. In those cases, the alt attribute must be present but must be empty.

Here the icons are next to text that conveys the same meaning, so they have an empty alt attribute:

<nav>
 <p><a href="/help/"><img src="/icons/help.png" alt=""> Help</a></p>
 <p><a href="/configure/"><img src="/icons/configuration.png" alt="">
 Configuration Tools</a></p>
</nav>

In other cases, the icon has no text next to it describing what it means; the icon is supposed to be self-explanatory. In those cases, an equivalent textual label must be given in the alt attribute.

Here, posts on a news site are labeled with an icon indicating their topic.

<body>
 <article>
  <header>
   <h1>Ratatouille wins <i>Best Movie of the Year</i> award</h1>
   <p><img src="movies.png" alt="Movies"></p>
  </header>
  <p>Pixar has won yet another <i>Best Movie of the Year</i> award,
  making this its 8th win in the last 12 years.</p>
 </article>
 <article>
  <header>
   <h1>Latest TWiT episode is online</h1>
   <p><img src="podcasts.png" alt="Podcasts"></p>
  </header>
  <p>The latest TWiT episode has been posted, in which we hear
  several tech news stories as well as learning much more about the
  iPhone. This week, the panelists compare how reflective their
  iPhones' Apple logos are.</p>
 </article>
</body>

Many pages include logos, insignia, flags, or emblems, which stand for a particular entity such as a company, organization, project, band, software package, country, or some such.

If the logo is being used to represent the entity, e.g. as a page heading, the alt attribute must contain the name of the entity being represented by the logo. The alt attribute must not contain text like the word "logo", as it is not the fact that it is a logo that is being conveyed, it's the entity itself.

If the logo is being used next to the name of the entity that it represents, then the logo is supplemental, and its alt attribute must instead be empty.

If the logo is merely used as decorative material (as branding, or, for example, as a side image in an article that mentions the entity to which the logo belongs), then the entry below on purely decorative images applies. If the logo is actually being discussed, then it is being used as a phrase or paragraph (the description of the logo) with an alternative graphical representation (the logo itself), and the first entry above applies.

In the following snippets, all four of the above cases are present. First, we see a logo used to represent a company:

<h1><img src="XYZ.gif" alt="The XYZ company"></h1>

Next, we see a paragraph which uses a logo right next to the company name, and so doesn't have any alternative text:

<article>
 <h2>News</h2>
 <p>We have recently been looking at buying the <img src="alpha.gif"
 alt=""> ΑΒΓ company, a small Greek company
 specializing in our type of product.</p>

In this third snippet, we have a logo being used in an aside, as part of the larger article discussing the acquisition:

 <aside><p><img src="alpha-large.gif" alt=""></p></aside>
 <p>The ΑΒΓ company has had a good quarter, and our
 pie chart studies of their accounts suggest a much bigger blue slice
 than its green and orange slices, which is always a good sign.</p>
</article>

Finally, we have an opinion piece talking about a logo, and the logo is therefore described in detail in the alternative text.

<p>Consider for a moment their logo:</p>

<p><img src="/images/logo" alt="It consists of a green circle with a
green question mark centered inside it."></p>

<p>How unoriginal can you get? I mean, oooooh, a question mark, how
<em>revolutionary</em>, how utterly <em>ground-breaking</em>, I'm
sure everyone will rush to adopt those specifications now! They could
at least have tried for some sort of, I don't know, sequence of
rounded squares with varying shades of green and bold white outlines,
at least that would look good on the cover of a blue book.</p>

This example shows how the alternative text should be written such that if the image isn't available, and the text is used instead, the text flows seamlessly into the surrounding text, as if the image had never been there in the first place.

4.8.2.1.4 Text that has been rendered to a graphic for typographical effect

Sometimes, an image just consists of text, and the purpose of the image is not to highlight the actual typographic effects used to render the text, but just to convey the text itself.

In such cases, the alt attribute must be present but must consist of the same text as written in the image itself.

Consider a graphic containing the text "Earth Day", but with the letters all decorated with flowers and plants. If the text is merely being used as a heading, to spice up the page for graphical users, then the correct alternative text is just the same text "Earth Day", and no mention need be made of the decorations:

<h1><img src="earthdayheading.png" alt="Earth Day"></h1>
4.8.2.1.5 A graphical representation of some of the surrounding text

In many cases, the image is actually just supplementary, and its presence merely reinforces the surrounding text. In these cases, the alt attribute must be present but its value must be the empty string.

In general, an image falls into this category if removing the image doesn't make the page any less useful, but including the image makes it a lot easier for users of visual browsers to understand the concept.

A flowchart that repeats the previous paragraph in graphical form:

<p>The network passes data to the Tokenizer stage, which
passes data to the Tree Construction stage. From there, data goes
to both the DOM and to Script Execution. Script Execution is
linked to the DOM, and, using document.write(), passes data to
the Tokenizer.</p>
<p><img src="images/parsing-model-overview.png" alt=""></p>

In these cases, it would be wrong to include alternative text that consists of just a caption. If a caption is to be included, then either the title attribute can be used, or the figure and legend elements can be used. In the latter case, the image would in fact be a phrase or paragraph with an alternative graphical representation, and would thus require alternative text.

<!-- Using the title="" attribute -->
<p>The network passes data to the Tokenizer stage, which
passes data to the Tree Construction stage. From there, data goes
to both the DOM and to Script Execution. Script Execution is
linked to the DOM, and, using document.write(), passes data to
the Tokenizer.</p>
<p><img src="images/parsing-model-overview.png" alt=""
        title="Flowchart representation of the parsing model."></p>
<!-- Using <figure> and <legend> -->
<p>The network passes data to the Tokenizer stage, which
passes data to the Tree Construction stage. From there, data goes
to both the DOM and to Script Execution. Script Execution is
linked to the DOM, and, using document.write(), passes data to
the Tokenizer.</p>
<figure>
 <img src="images/parsing-model-overview.png" alt="The Network leads
 to the Tokenizer, which leads to the Tree Construction. The Tree
 Construction leads to two items. The first is Script Execution, which
 leads via document.write() back to the Tokenizer. The second item
 from which Tree Construction leads is the DOM. The DOM is related to
 the Script Execution.">
 <legend>Flowchart representation of the parsing model.</legend>
</figure>
<!-- This is WRONG. Do not do this. Instead, do what the above examples do. -->
<p>The network passes data to the Tokenizer stage, which
passes data to the Tree Construction stage. From there, data goes
to both the DOM and to Script Execution. Script Execution is
linked to the DOM, and, using document.write(), passes data to
the Tokenizer.</p>
<p><img src="images/parsing-model-overview.png"
        alt="Flowchart representation of the parsing model."></p>
<!-- Never put the image's caption in the alt="" attribute! -->

A graph that repeats the previous paragraph in graphical form:

<p>According to a study covering several billion pages,
about 62% of documents on the Web in 2007 triggered the Quirks
rendering mode of Web browsers, about 30% triggered the Almost
Standards mode, and about 9% triggered the Standards mode.</p>
<p><img src="rendering-mode-pie-chart.png" alt=""></p>
4.8.2.1.6 A purely decorative image that doesn't add any information

In general, if an image is decorative but isn't especially page-specific, for example an image that forms part of a site-wide design scheme, the image should be specified in the site's CSS, not in the markup of the document.

However, a decorative image that isn't discussed by the surrounding text still has some relevance can be included in a page using the img element. Such images are decorative, but still form part of the content. In these cases, the alt attribute must be present but its value must be the empty string.

Examples where the image is purely decorative despite being relevant would include things like a photo of the Black Rock City landscape in a blog post about an event at Burning Man, or an image of a painting inspired by a poem, on a page reciting that poem. The following snippet shows an example of the latter case (only the first verse is included in this snippet):

<h1>The Lady of Shalott</h1>
<p><img src="shalott.jpeg" alt=""></p>
<p>On either side the river lie<br>
Long fields of barley and of rye,<br>
That clothe the wold and meet the sky;<br>
And through the field the road run by<br>
To many-tower'd Camelot;<br>
And up and down the people go,<br>
Gazing where the lilies blow<br>
Round an island there below,<br>
The island of Shalott.</p>

When a picture has been sliced into smaller image files that are then displayed together to form the complete picture again, one of the images must have its alt attribute set as per the relevant rules that would be appropriate for the picture as a whole, and then all the remaining images must have their alt attribute set to the empty string.

In the following example, a picture representing a company logo for XYZ Corp has been split into two pieces, the first containing the letters "XYZ" and the second with the word "Corp". The alternative text ("XYZ Corp") is all in the first image.

<h1><img src="logo1.png" alt="XYZ Corp"><img src="logo2.png" alt=""></h1>

In the following example, a rating is shown as three filled stars and two empty stars. While the alternative text could have been "★★★☆☆", the author has instead decided to more helpfully give the rating in the form "3 out of 5". That is the alternative text of the first image, and the rest have blank alternative text.

<p>Rating: <meter max=5 value=3><img src="1" alt="3 out of 5"
  ><img src="1" alt=""><img src="1" alt=""><img src="0" alt=""
  ><img src="0" alt=""></meter></p>

Generally, image maps should be used instead of slicing an image for links.

However, if an image is indeed sliced and any of the components of the sliced picture are the sole contents of links, then one image per link must have alternative text in its alt attribute representing the purpose of the link.

In the following example, a picture representing the flying spaghetti monster emblem, with each of the left noodly appendages and the right noodly appendages in different images, so that the user can pick the left side or the right side in an adventure.

<h1>The Church</h1>
<p>You come across a flying spaghetti monster. Which side of His
Noodliness do you wish to reach out for?</p>
<p><a href="?go=left" ><img src="fsm-left.png"  alt="Left side. "></a
  ><img src="fsm-middle.png" alt=""
  ><a href="?go=right"><img src="fsm-right.png" alt="Right side."></a></p>
4.8.2.1.9 A key part of the content

In some cases, the image is a critical part of the content. This could be the case, for instance, on a page that is part of a photo gallery. The image is the whole point of the page containing it.

How to provide alternative text for an image that is a key part of the content depends on the image's provenance.

The general case

When it is possible for detailed alternative text to be provided, for example if the image is part of a series of screenshots in a magazine review, or part of a comic strip, or is a photograph in a blog entry about that photograph, text that can serve as a substitute for the image must be given as the contents of the alt attribute.

A screenshot in a gallery of screenshots for a new OS, with some alternative text:

<figure>
 <img src="KDE%20Light%20desktop.png"
      alt="The desktop is blue, with icons along the left hand side in
           two columns, reading System, Home, K-Mail, etc. A window is
           open showing that menus wrap to a second line if they
           cannot fit in the window. The window has a list of icons
           along the top, with an address bar below it, a list of
           icons for tabs along the left edge, a status bar on the
           bottom, and two panes in the middle. The desktop has a bar
           at the bottom of the screen with a few buttons, a pager, a
           list of open applications, and a clock.">
 <legend>Screenshot of a KDE desktop.</legend>
</figure>

A graph in a financial report:

<img src="sales.gif"
     title="Sales graph"
     alt="From 1998 to 2005, sales increased by the following percentages
     with each year: 624%, 75%, 138%, 40%, 35%, 9%, 21%">

Note that "sales graph" would be inadequate alternative text for a sales graph. Text that would be a good caption is not generally suitable as replacement text.

Images that defy a complete description

In certain cases, the nature of the image might be such that providing thorough alternative text is impractical. For example, the image could be indistinct, or could be a complex fractal, or could be a detailed topographical map.

In these cases, the alt attribute must contain some suitable alternative text, but it may be somewhat brief.

Sometimes there simply is no text that can do justice to an image. For example, there is little that can be said to usefully describe a Rorschach inkblot test. However, a description, even if brief, is still better than nothing:

<figure>
 <img src="/commons/a/a7/Rorschach1.jpg" alt="A shape with left-right
 symmetry with indistinct edges, with a small gap in the center, two
 larger gaps offset slightly from the center, with two similar gaps
 under them. The outline is wider in the top half than the bottom
 half, with the sides extending upwards higher than the center, and
 the center extending below the sides.">
 <legend>A black outline of the first of the ten cards
 in the Rorschach inkblot test.</legend>
</figure>

Note that the following would be a very bad use of alternative text:

<!-- This example is wrong. Do not copy it. -->
<figure>
 <img src="/commons/a/a7/Rorschach1.jpg" alt="A black outline
 of the first of the ten cards in the Rorschach inkblot test.">
 <legend>A black outline of the first of the ten cards
 in the Rorschach inkblot test.</legend>
</figure>

Including the caption in the alternative text like this isn't useful because it effectively duplicates the caption for users who don't have images, taunting them twice yet not helping them any more than if they had only read or heard the caption once.

Another example of an image that defies full description is a fractal, which, by definition, is infinite in complexity.

The following example shows one possible way of providing alternative text for the full view of an image of the Mandelbrot set.

<img src="ms1.jpeg" alt="The Mandelbrot set appears as a cardioid with
its cusp on the real axis in the positive direction, with a smaller
bulb aligned along the same center line, touching it in the negative
direction, and with these two shapes being surrounded by smaller bulbs
of various sizes.">
Images whose contents are not known

In some unfortunate cases, there might be no alternative text available at all, either because the image is obtained in some automated fashion without any associated alternative text (e.g. a Webcam), or because the page is being generated by a script using user-provided images where the user did not provide suitable or usable alternative text (e.g. photograph sharing sites), or because the author does not himself know what the images represent (e.g. a blind photographer sharing an image on his blog).

In such cases, the alt attribute's value may be omitted, but one of the following conditions must be met as well:

Such cases are to be kept to an absolute minimum. If there is even the slightest possibility of the author having the ability to provide real alternative text, then it would not be acceptable to omit the alt attribute.

A photo on a photo-sharing site, if the site received the image with no metadata other than the caption:

<figure>
 <img src="1100670787_6a7c664aef.jpg">
 <legend>Bubbles traveled everywhere with us.</legend>
</figure>

It could also be marked up like this:

<article>
 <h1>Bubbles traveled everywhere with us.</h1>
 <img src="1100670787_6a7c664aef.jpg">
</article>

In either case, though, it would be better if a detailed description of the important parts of the image obtained from the user and included on the page.

A blind user's blog in which a photo taken by the user is shown. Initially, the user might not have any idea what the photo he took shows:

<article>
 <h1>I took a photo</h1>
 <p>I went out today and took a photo!</p>
 <figure>
  <img src="photo2.jpeg">
  <legend>A photograph taken blindly from my front porch.</legend>
 </figure>
</article>

Eventually though, the user might obtain a description of the image from his friends and could then include alternative text:

<article>
 <h1>I took a photo</h1>
 <p>I went out today and took a photo!</p>
 <figure>
  <img src="photo2.jpeg" alt="The photograph shows my hummingbird
  feeder hanging from the edge of my roof. It is half full, but there
  are no birds around. In the background, out-of-focus trees fill the
  shot. The feeder is made of wood with a metal grate, and it contains
  peanuts. The edge of the roof is wooden too, and is painted white
  with light blue streaks.">
  <legend>A photograph taken blindly from my front porch.</legend>
 </figure>
</article>

Sometimes the entire point of the image is that a textual description is not available, and the user is to provide the description. For instance, the point of a CAPTCHA image is to see if the user can literally read the graphic. Here is one way to mark up a CAPTCHA (note the title attribute):

<p><label>What does this image say?
<img src="captcha.cgi?id=8934" title="CAPTCHA">
<input type=text name=captcha></label>
(If you cannot see the image, you can use an <a
href="?audio">audio</a> test instead.)</p>

Another example would be software that displays images and asks for alternative text precisely for the purpose of then writing a page with correct alternative text. Such a page could have a table of images, like this:

<table>
 <thead>
  <tr> <th> Image <th> Description
 <tbody>
  <tr>
   <td> <img src="2421.png" title="Image 640 by 100, filename 'banner.gif'">
   <td> <input name="alt2421">
  <tr>
   <td> <img src="2422.png" title="Image 200 by 480, filename 'ad3.gif'">
   <td> <input name="alt2422">
</table>

Notice that even in this example, as much useful information as possible is still included in the title attribute.

Since some users cannot use images at all (e.g. because they have a very slow connection, or because they are using a text-only browser, or because they are listening to the page being read out by a hands-free automobile voice Web browser, or simply because they are blind), the alt attribute is only allowed to be omitted rather than being provided with replacement text when no alternative text is available and none can be made available, as in the above examples. Lack of effort from the part of the author is not an acceptable reason for omitting the alt attribute.

4.8.2.1.10 An image not intended for the user

Generally authors should avoid using img elements for purposes other than showing images.

If an img element is being used for purposes other than showing an image, e.g. as part of a service to count page views, then the alt attribute must be the empty string.

In such cases, the width and height attributes should both be set to zero.

4.8.2.1.11 An image in an e-mail or private document intended for a specific person who is known to be able to view images

This section does not apply to documents that are publicly accessible, or whose target audience is not necessarily personally known to the author, such as documents on a Web site, e-mails sent to public mailing lists, or software documentation.

When an image is included in a private communication (such as an HTML e-mail) aimed at a specific person who is known to be able to view images, the alt attribute may be omitted. However, even in such cases it is strongly recommended that alternative text be included (as appropriate according to the kind of image involved, as described in the above entries), so that the e-mail is still usable should the user use a mail client that does not support images, or should the document be forwarded on to other users whose abilities might not include easily seeing images.

4.8.2.1.12 General guidelines

The most general rule to consider when writing alternative text is the following: the intent is that replacing every image with the text of its alt attribute not change the meaning of the page.

So, in general, alternative text can be written by considering what one would have written had one not been able to include the image.

A corollary to this is that the alt attribute's value should never contain text that could be considered the image's caption, title, or legend. It is supposed to contain replacement text that could be used by users instead of the image; it is not meant to supplement the image. The title attribute can be used for supplemental information.

One way to think of alternative text is to think about how you would read the page containing the image to someone over the phone, without mentioning that there is an image present. Whatever you say instead of the image is typically a good start for writing the alternative text.

4.8.3 The iframe element

Status: Working draft

Categories
Flow content.
Phrasing content.
Embedded content.
Interactive content.
Contexts in which this element may be used:
Where embedded content is expected.
Content model:
Text that conforms to the requirements given in the prose.
Content attributes:
Global attributes
src
name
sandbox
seamless
width
height
DOM interface:
interface HTMLIFrameElement : HTMLElement {
           attribute DOMString src;
           attribute DOMString name;
           attribute DOMString sandbox;
           attribute boolean seamless;
           attribute DOMString width;
           attribute DOMString height;
  readonly attribute Document contentDocument;
  readonly attribute WindowProxy contentWindow;
};

The iframe element represents a nested browsing context.

The src attribute gives the address of a page that the nested browsing context is to contain. The attribute, if present, must be a valid URL.

The name attribute, if present, must be a valid browsing context name. The given value is used to name the nested browsing context.


The sandbox attribute, when specified, enables a set of extra restrictions on any content hosted by the iframe. Its value must be an unordered set of unique space-separated tokens. The allowed values are allow-same-origin, allow-forms, and allow-scripts. When the attribute is set, the content is treated as being from a unique origin, forms and scripts are disabled, links are prevented from targeting other browsing contexts, and plugins are disabled. The allow-same-origin token allows the content to be treated as being from the same origin instead of forcing it into a unique origin, and the allow-forms and allow-scripts tokens re-enable forms and scripts respectively (though scripts are still prevented from creating popups).

In this example, some completely-unknown, potentially hostile, user-provided HTML content is embedded in a page. Because it is sandboxed, it is treated by the user agent as being from a unique origin, despite the content being served from the same site. Thus it is affected by all the normal cross-site restrictions. In addition, the embedded page has scripting disabled, plugins disabled, forms disabled, and it cannot navigate any frames or windows other than itself (or any frames or windows it itself embeds).

<p>We're not scared of you! Here is your content, unedited:</p>
<iframe sandbox src="getusercontent.cgi?id=12193"></iframe>

Note that cookies are still sent to the server in the getusercontent.cgi request, though they are not visible in the document.cookie DOM attribute.

In this example, a gadget from another site is embedded. The gadget has scripting and forms enabled, and the origin sandbox restrictions are lifted, allowing the gadget to communicate with its originating server. The sandbox is still useful, however, as it disables plugins and popups, thus reducing the risk of the user being exposed to malware and other annoyances.

<iframe sandbox="allow-same-origin allow-forms allow-scripts"
        src="http://maps.example.com/embedded.html"></iframe>

The seamless attribute is a boolean attribute. When specified, it indicates that the iframe element's browsing context is to be rendered in a manner that makes it appear to be part of the containing document (seamlessly included in the parent document).

The attribute can be set or removed dynamically, with the rendering updating in tandem.

In this example, the site's navigation is embedded using a client-side include using an iframe. Any links in the iframe will, in new user agents, be automatically opened in the iframe's parent browsing context; for legacy user agents, the site could also include a base element with a target attribute with the value _parent. Similarly, in new user agents the styles of the parent page will be automatically applied to the contents of the frame, but to support legacy user agents authors might wish to include the styles explicitly.

<nav><iframe seamless src="nav.include.html"></iframe></nav>

The iframe element supports dimension attributes for cases where the embedded content has specific dimensions (e.g. ad units have well-defined dimensions).

An iframe element never has fallback content, as it will always create a nested browsing context, regardless of whether the specified initial contents are successfully used.

Descendants of iframe elements represent nothing. (In legacy user agents that do not support iframe elements, the contents would be parsed as markup that could act as fallback content.)

When used in HTML documents, the allowed content model of iframe elements is text, except that invoking the HTML fragment parsing algorithm with the iframe element as the context element and the text contents as the input must result in a list of nodes that are all phrasing content, with no parse errors having occurred, with no script elements being anywhere in the list or as descendants of elements in the list, and with all the elements in the list (including their descendants) being themselves conforming.

The iframe element must be empty in XML documents.

The HTML parser treats markup inside iframe elements as text.

4.8.4 The embed element

Status: Working draft

Categories
Flow content.
Phrasing content.
Embedded content.
Interactive content.
Contexts in which this element may be used:
Where embedded content is expected.
Content model:
Empty.
Content attributes:
Global attributes
src
type
width
height
Any other attribute that has no namespace (see prose).
DOM interface:
interface HTMLEmbedElement : HTMLElement {
           attribute DOMString src;
           attribute DOMString type;
           attribute DOMString width;
           attribute DOMString height;
};

The embed element represents an integration point for an external (typically non-HTML) application or interactive content.

The src attribute gives the address of the resource being embedded. The attribute, if present, must contain a valid URL.

The type attribute, if present, gives the MIME type of the plugin to instantiate. The value must be a valid MIME type, optionally with parameters. If both the type attribute and the src attribute are present, then the type attribute must specify the same type as the explicit Content-Type metadata of the resource given by the src attribute.

Any (namespace-less) attribute may be specified on the embed element, so long as its name is XML-compatible and contains no characters in the range U+0041 .. U+005A (LATIN CAPITAL LETTER A LATIN CAPITAL LETTER Z).

All attributes in HTML documents get lowercased automatically, so the restriction on uppercase letters doesn't affect such documents.

The embed element supports dimension attributes.

4.8.5 The object element

Status: Working draft

Categories
Flow content.
Phrasing content.
Embedded content.
If the element has a usemap attribute: Interactive content.
Listed, submittable, form-associated element.
Contexts in which this element may be used:
Where embedded content is expected.
Content model:
Zero or more param elements, then, transparent.
Content attributes:
Global attributes
data
type
name
usemap
form
width
height
DOM interface:
interface HTMLObjectElement : HTMLElement {
           attribute DOMString data;
           attribute DOMString type;
           attribute DOMString name;
           attribute DOMString useMap;
  readonly attribute HTMLFormElement form;
           attribute DOMString width;
           attribute DOMString height;
  readonly attribute Document contentDocument;
  readonly attribute WindowProxy contentWindow;
};

The object element can represent an external resource, which, depending on the type of the resource, will either be treated as an image, as a nested browsing context, or as an external resource to be processed by a plugin.

The data attribute, if present, specifies the address of the resource. If present, the attribute must be a valid URL.

The type attribute, if present, specifies the type of the resource. If present, the attribute must be a valid MIME type, optionally with parameters.

One or both of the data and type attributes must be present.

The name attribute, if present, must be a valid browsing context name. The given value is used to name the nested browsing context, if applicable.

The usemap attribute, if present while the object element represents an image, can indicate that the object has an associated image map.

The form attribute is used to explicitly associate the object element with its form owner.

The object element supports dimension attributes.

In the following example, a Java applet is embedded in a page using the object element. (Generally speaking, it is better to avoid using applets like these and instead use native JavaScript and HTML to provide the functionality, since that way the application will work on all Web browsers without requiring a third-party plugin. Many devices, especially embedded devices, do not support third-party technologies like Java.)

<figure>
 <object type="application/x-java-applet">
  <param name="code" value="MyJavaClass">
  <p>You do not have Java available, or it is disabled.</p>
 </object>
 <legend>My Java Clock</legend>
</figure>

In this example, an HTML page is embedded in another using the object element.

<figure>
 <object data="clock.html"></object>
 <legend>My HTML Clock</legend>
</figure>

4.8.6 The param element

Status: Implemented and widely deployed

Categories
None.
Contexts in which this element may be used:
As a child of an object element, before any flow content.
Content model:
Empty.
Content attributes:
Global attributes
name
value
DOM interface:
interface HTMLParamElement : HTMLElement {
           attribute DOMString name;
           attribute DOMString value;
};

The param element defines parameters for plugins invoked by object elements. It does not represent anything on its own.

The name attribute gives the name of the parameter.

The value attribute gives the value of the parameter.

Both attributes must be present. They may have any value.

4.8.7 The video element

Status: Last call for comments

Categories
Flow content.
Phrasing content.
Embedded content.
If the element has a controls attribute: Interactive content.
Contexts in which this element may be used:
Where embedded content is expected.
Content model:
If the element has a src attribute: transparent, but with no media element descendants.
If the element does not have a src attribute: one or more source elements, then, transparent, but with no media element descendants.
Content attributes:
Global attributes
src
poster
autobuffer
autoplay
loop
controls
width
height
DOM interface:
interface HTMLVideoElement : HTMLMediaElement {
           attribute DOMString width;
           attribute DOMString height;
  readonly attribute unsigned long videoWidth;
  readonly attribute unsigned long videoHeight;
           attribute DOMString poster;
};

A video element represents a video or movie.

Content may be provided inside the video element; it is intended for older Web browsers which do not support video, so that legacy video plugins can be tried, or to show text to the users of these older browser informing them of how to access the video contents.

In particular, this content is not fallback content intended to address accessibility concerns. To make video content accessible to the blind, deaf, and those with other physical or cognitive disabilities, authors are expected to provide alternative media streams and/or to embed accessibility aids (such as caption or subtitle tracks) into their media streams.

The video element is a media element whose media data is ostensibly video data, possibly with associated audio data.

The src, autobuffer, autoplay, loop, and controls attributes are the attributes common to all media elements.

The poster attribute gives the address of an image file that the user agent can show while no video data is available. The attribute, if present, must contain a valid URL.

The image given by the poster attribute, the poster frame, is intended to be a representative frame of the video (typically one of the first non-blank frames) that gives the user an idea of what the video is like.

video . videoWidth
video . videoHeight

These attributes return the intrinsic dimensions of the video, or zero if the dimensions are not known.

The video element supports dimension attributes.

4.8.8 The audio element

Status: Last call for comments

Categories
Flow content.
Phrasing content.
Embedded content.
If the element has a controls attribute: Interactive content.
Contexts in which this element may be used:
Where embedded content is expected.
Content model:
If the element has a src attribute: transparent, but with no media element descendants.
If the element does not have a src attribute: one or more source elements, then, transparent, but with no media element descendants.
Content attributes:
Global attributes
src
autobuffer
autoplay
loop
controls
DOM interface:
[NamedConstructor=Audio(),
 NamedConstructor=Audio(in DOMString src)]
interface HTMLAudioElement : HTMLMediaElement {};

An audio element represents a sound or audio stream.

Content may be provided inside the audio element; it is intended for older Web browsers which do not support audio, so that legacy audio plugins can be tried, or to show text to the users of these older browser informing them of how to access the audio contents.

In particular, this content is not fallback content intended to address accessibility concerns. To make audio content accessible to the deaf or to those with other physical or cognitive disabilities, authors are expected to provide alternative media streams and/or to embed accessibility aids (such as transcriptions) into their media streams.

The audio element is a media element whose media data is ostensibly audio data.

The src, autobuffer, autoplay, loop, and controls attributes are the attributes common to all media elements.

audio = new Audio( [ url ] )

Returns a new audio element, with the src attribute set to the value passed in the argument, if applicable.

4.8.9 The source element

Status: Last call for comments

Categories
None.
Contexts in which this element may be used:
As a child of a media element, before any flow content.
Content model:
Empty.
Content attributes:
Global attributes
src
type
media
DOM interface:
interface HTMLSourceElement : HTMLElement {
           attribute DOMString src;
           attribute DOMString type;
           attribute DOMString media;
};

The source element allows authors to specify multiple media resources for media elements. It does not represent anything on its own.

The src attribute gives the address of the media resource. The value must be a valid URL. This attribute must be present.

The type attribute gives the type of the media resource, to help the user agent determine if it can play this media resource before fetching it. If specified, its value must be a valid MIME type. The codecs parameter may be specified and might be necessary to specify exactly how the resource is encoded. [RFC4281]

The following list shows some examples of how to use the codecs= MIME parameter in the type attribute.

H.264 Simple baseline profile video (main and extended video compatible) level 3 and Low-Complexity AAC audio in MP4 container
<source src='video.mp4' type='video/mp4; codecs="avc1.42E01E, mp4a.40.2"'>
H.264 Extended profile video (baseline-compatible) level 3 and Low-Complexity AAC audio in MP4 container
<source src='video.mp4' type='video/mp4; codecs="avc1.58A01E, mp4a.40.2"'>
H.264 Main profile video level 3 and Low-Complexity AAC audio in MP4 container
<source src='video.mp4' type='video/mp4; codecs="avc1.4D401E, mp4a.40.2"'>
H.264 'High' profile video (incompatible with main, baseline, or extended profiles) level 3 and Low-Complexity AAC audio in MP4 container
<source src='video.mp4' type='video/mp4; codecs="avc1.64001E, mp4a.40.2"'>
MPEG-4 Visual Simple Profile Level 0 video and Low-Complexity AAC audio in MP4 container
<source src='video.mp4' type='video/mp4; codecs="mp4v.20.8, mp4a.40.2"'>
MPEG-4 Advanced Simple Profile Level 0 video and Low-Complexity AAC audio in MP4 container
<source src='video.mp4' type='video/mp4; codecs="mp4v.20.240, mp4a.40.2"'>
MPEG-4 Visual Simple Profile Level 0 video and AMR audio in 3GPP container
<source src='video.3gp' type='video/3gpp; codecs="mp4v.20.8, samr"'>
Theora video and Vorbis audio in Ogg container
<source src='video.ogv' type='video/ogg; codecs="theora, vorbis"'>
Theora video and Speex audio in Ogg container
<source src='video.ogv' type='video/ogg; codecs="theora, speex"'>
Vorbis audio alone in Ogg container
<source src='audio.ogg' type='audio/ogg; codecs=vorbis'>
Speex audio alone in Ogg container
<source src='audio.spx' type='audio/ogg; codecs=speex'>
FLAC audio alone in Ogg container
<source src='audio.oga' type='audio/ogg; codecs=flac'>
Dirac video and Vorbis audio in Ogg container
<source src='video.ogv' type='video/ogg; codecs="dirac, vorbis"'>
Theora video and Vorbis audio in Matroska container
<source src='video.mkv' type='video/x-matroska; codecs="theora, vorbis"'>

The media attribute gives the intended media type of the media resource, to help the user agent determine if this media resource is useful to the user before fetching it. Its value must be a valid media query. [MQ]

4.8.10 Media elements

Status: Last call for comments

Media elements implement the following interface:

interface HTMLMediaElement : HTMLElement {

  // error state
  readonly attribute MediaError error;

  // network state
           attribute DOMString src;
  readonly attribute DOMString currentSrc;
  const unsigned short NETWORK_EMPTY = 0;
  const unsigned short NETWORK_IDLE = 1;
  const unsigned short NETWORK_LOADING = 2;
  const unsigned short NETWORK_LOADED = 3;
  const unsigned short NETWORK_NO_SOURCE = 4;
  readonly attribute unsigned short networkState;
           attribute boolean autobuffer;
  readonly attribute TimeRanges buffered;
  void load();
  DOMString canPlayType(in DOMString type);

  // ready state
  const unsigned short HAVE_NOTHING = 0;
  const unsigned short HAVE_METADATA = 1;
  const unsigned short HAVE_CURRENT_DATA = 2;
  const unsigned short HAVE_FUTURE_DATA = 3;
  const unsigned short HAVE_ENOUGH_DATA = 4;
  readonly attribute unsigned short readyState;
  readonly attribute boolean seeking;

  // playback state
           attribute float currentTime;
  readonly attribute float startTime;
  readonly attribute float duration;
  readonly attribute boolean paused;
           attribute float defaultPlaybackRate;
           attribute float playbackRate;
  readonly attribute TimeRanges played;
  readonly attribute TimeRanges seekable;
  readonly attribute boolean ended;
           attribute boolean autoplay;
           attribute boolean loop;
  void play();
  void pause();

  // cue ranges
  void addCueRange(in DOMString className, in DOMString id, in float start, in float end, in boolean pauseOnExit, in CueRangeCallback enterCallback, in CueRangeCallback exitCallback);
  void removeCueRanges(in DOMString className);

  // controls
           attribute boolean controls;
           attribute float volume;
           attribute boolean muted;
};

[Callback=FunctionOnly, NoInterfaceObject]
interface CueRangeCallback {
  void handleEvent(in DOMString id);
};

The media element attributes, src, autobuffer, autoplay, loop, and controls, apply to all media elements. They are defined in this section.

Media elements are used to present audio data, or video and audio data, to the user. This is referred to as media data in this section, since this section applies equally to media elements for audio or for video. The term media resource is used to refer to the complete set of media data, e.g. the complete video file, or complete audio file.

4.8.10.1 Error codes
media . error

Returns a MediaError object representing the current error state of the element.

Returns null if there is no error.

interface MediaError {
  const unsigned short MEDIA_ERR_ABORTED = 1;
  const unsigned short MEDIA_ERR_NETWORK = 2;
  const unsigned short MEDIA_ERR_DECODE = 3;
  const unsigned short MEDIA_ERR_SRC_NOT_SUPPORTED = 4;
  readonly attribute unsigned short code;
};
media . error . code

Returns the current error's error code, from the list below.

MEDIA_ERR_ABORTED (numeric value 1)
The fetching process for the media resource was aborted by the user agent at the user's request.
MEDIA_ERR_NETWORK (numeric value 2)
A network error of some description caused the user agent to stop fetching the media resource, after the resource was established to be usable.
MEDIA_ERR_DECODE (numeric value 3)
An error of some description occurred while decoding the media resource, after the resource was established to be usable.
MEDIA_ERR_SRC_NOT_SUPPORTED (numeric value 4)
The media resource indicated by the src attribute was not suitable.
4.8.10.2 Location of the media resource

The src content attribute on media elements gives the address of the media resource (video, audio) to show. The attribute, if present, must contain a valid URL.

media . currentSrc

Returns the address of the current media resource.

Returns the empty string when there is no media resource.

There are two ways to specify a media resource, the src attribute, or source elements. The attribute overrides the elements.

4.8.10.3 MIME types

A media resource can be described in terms of its type, specifically a MIME type, optionally with a codecs parameter. [RFC4281].

Types are usually somewhat incomplete descriptions; for example "video/mpeg" doesn't say anything except what the container type is, and even a type like "video/mp4; codecs="avc1.42E01E, mp4a.40.2"" doesn't include information like the actual bitrate (only the maximum bitrate). Thus, given a type, a user agent can often only know whether it might be able to play media of that type (with varying levels of confidence), or whether it definitely cannot play media of that type.

A type that the user agent knows it cannot render is one that describes a resource that the user agent definitely does not support, for example because it doesn't recognize the container type, or it doesn't support the listed codecs.

The MIME type "application/octet-stream" is never a type that the user agent knows it cannot render. User agents must treat that type as equivalent to the lack of any explicit Content-Type metadata when it is used to label a potential media resource.

media . canPlayType(type)

Returns the empty string (a negative response), "maybe", or "probably" based on how confident the user agent is that it can play media resources of the given type.

This script tests to see if the user agent supports a (fictional) new format to dynamically decide whether to use a video element or a plugin:

<section id="video">
 <p><a href="playing-cats.nfv">Download video</a></p>
</section>
<script>
 var videoSection = document.getElementById('video');
 var videoElement = document.createElement('video');
 var support = videoElement.canPlayType('video/x-new-fictional-format;codecs="kittens,bunnies"');
 if (support != "probably" && "New Fictional Video Plug-in" in navigator.plugins) {
   // not confident of browser support
   // but we have a plugin
   // so use plugin instead
   videoElement = document.createElement("embed");
 } else if (support == "") {
   // no support from browser and no plugin
   // do nothing
   videoElement = null;
 }
 if (videoElement) {
   while (videoSection.hasChildNodes())
     videoSection.removeChild(videoSection.firstChild);
   videoElement.setAttribute("src", "playing-cats.nfv");
   videoSection.appendChild(videoElement);
 }
</script>

The type attribute of the source element allows the user agent to avoid downloading resources that use formats it cannot render.

4.8.10.4 Network states
media . networkState

Returns the current state of network activity for the element, from the codes in the list below.

NETWORK_EMPTY (numeric value 0)
The element has not yet been initialized. All attributes are in their initial states.
NETWORK_IDLE (numeric value 1)
The element's resource, but it is not actually using the network at this time.
NETWORK_LOADING (numeric value 2)
The user agent is actively trying to download data.
NETWORK_LOADED (numeric value 3)
The entire media resource has been obtained and is available to the user agent locally. Network connectivity could be lost without affecting the media playback.
NETWORK_NO_SOURCE (numeric value 4)
The element's resource to use.

Some resources, e.g. streaming Web radio, can never reach the NETWORK_LOADED state.

4.8.10.5 Loading the media resource
media . load()

Causes the element to reset and start selecting and loading a new media resource from scratch.

The autobuffer attribute is a boolean attribute. Its presence hints to the user agent that the author believes that the media element will likely be used, even though the element does not have an autoplay attribute. (The attribute has no effect if used in conjunction with the autoplay attribute, though including both is not an error.)

media . buffered

Returns a TimeRanges object that represents the ranges of the media resource that the user agent has buffered.

4.8.10.6 Offsets into the media resource

Status: Being considered for removal

media . duration

Returns the length of the media resource, in seconds.

Returns NaN if the duration isn't available.

Returns Infinity for unbounded streams.

media . currentTime [ = value ]

Returns the current playback position, in seconds.

Can be set, to seek to the given time.

Will throw an INVALID_STATE_ERR exception if there is no selected media resource. Will throw an INDEX_SIZE_ERR exception if the given time is not within the ranges to which the user agent can seek.

media . startTime

Returns the earliest possible position, in seconds. This is the time for the start of the current clip. It might not be zero if the clip's timeline is not zero-based, or if the resource is a streaming resource (in which case it gives the earliest time that the user agent is able to seek back to).

The loop attribute is a boolean attribute that, if specified, indicates that the media element is to seek back to the start of the media resource upon reaching the end.

4.8.10.7 The ready states
media . readyState

Returns a value that expresses the current state of the element with respect to rendering the current playback position, from the codes in the list below.

HAVE_NOTHING (numeric value 0)
No information regarding the media resource is available. No data for the current playback position is available. Media elements whose networkState attribute is NETWORK_EMPTY are always in the HAVE_NOTHING state.
HAVE_METADATA (numeric value 1)
Enough of the resource has been obtained that the duration of the resource is available. In the case of a video element, the dimensions of the video are also available. The API will no longer raise an exception when seeking. No media data is available for the immediate current playback position.
HAVE_CURRENT_DATA (numeric value 2)
Data for the immediate current playback position is available, but either not enough data is available that the user agent could successfully advance the current playback position in the direction of playback at all without immediately reverting to the HAVE_METADATA state, or there is no more data to obtain in the direction of playback. For example, in video this corresponds to the user agent having data from the current frame, but not the next frame; and to when playback has ended.
HAVE_FUTURE_DATA (numeric value 3)
Data for the immediate current playback position is available, as well as enough data for the user agent to advance the current playback position in the direction of playback at least a little without immediately reverting to the HAVE_METADATA state. For example, in video this corresponds to the user agent having data for at least the current frame and the next frame. The user agent cannot be in this state if playback has ended, as the current playback position can never advanced in this case.
HAVE_ENOUGH_DATA (numeric value 4)
All the conditions described for the HAVE_FUTURE_DATA state are met, and, in addition, the user agent estimates that data is being fetched at a rate where the current playback position, if it were to advance at the rate given by the defaultPlaybackRate attribute, would not overtake the available data before playback reaches the end of the media resource.

It is possible for the ready state of a media element to jump between these states discontinuously. For example, the state of a media element can jump straight from HAVE_METADATA to HAVE_ENOUGH_DATA without passing through the HAVE_CURRENT_DATA and HAVE_FUTURE_DATA states.

The autoplay attribute is a boolean attribute. When present, the user agent will automatically begin playback of the media resource as soon as it can do so without stopping.

Authors are urged to use the autoplay attribute rather than using script to trigger automatic playback, as this allows the user to override the automatic playback when it is not desired, e.g. when using a screen reader. Authors are also encouraged to consider not using the automatic playback behavior at all, and instead to let the user agent wait for the user to start playback explicitly.

4.8.10.8 Cue ranges
media . addCueRange(className, id, start, end, pauseOnExit, enterCallback, exitCallback)

Registers a range of time, given in seconds, and a pair of callbacks, the first of which will be invoked when the current playback position enters the range, and the second of which will be invoked when it exits the range. The callbacks are invoked with the given ID as their argument.

In addition, if the pauseOnExit argument is true, then playback will pause when it reaches the end of the range.

media . removeCueRange(className)

Removes all the ranges that were registered with the given class name.

4.8.10.9 Playing the media resource
media . paused

Returns true if playback is paused; false otherwise.

media . ended

Returns true if playback has reached the end of the media resource.

media . defaultPlaybackRate [ = value ]

Returns the default rate of playback, for when the user is not fast-forwarding or reversing through the media resource.

Can be set, to change the default rate of playback.

The default rate has no direct effect on playback, but if the user switches to a fast-forward mode, when they return to the normal playback mode, it is expected that the rate of playback will be returned to the default rate of playback.

media . playbackRate [ = value ]

Returns the current rate playback, where 1.0 is normal speed.

Can be set, to change the rate of playback.

media . played

Returns a TimeRanges object that represents the ranges of the media resource that the user agent has played.

media . play()

Sets the paused attribute to false, loading the media resource and beginning playback if necessary. If the playback had ended, will restart it from the start.

media . pause()

Sets the paused attribute to true, loading the media resource if necessary.

4.8.10.10 Seeking
media . seeking

Returns true if the user agent is currently seeking.

media . seekable

Returns a TimeRanges object that represents the ranges of the media resource to which it is possible for the user agent to seek.

4.8.10.11 User interface

The controls attribute is a boolean attribute. If present, it indicates that the author has not provided a scripted controller and would like the user agent to provide its own set of controls.

media . volume [ = value ]

Returns the current playback volume, as a number in the range 0.0 to 1.0, where 0.0 is the quietest and 1.0 the loudest.

Can be set, to change the volume.

Throws an INDEX_SIZE_ERR if the new value is not in the range 0.0 .. 1.0.

media . muted [ = value ]

Returns true if audio is muted, overriding the volume attribute, and false if the volume attribute is being honored.

Can be set, to change whether the audio is muted or not.

4.8.10.12 Time ranges

Objects implementing the TimeRanges interface represent a list of ranges (periods) of time.

interface TimeRanges {
  readonly attribute unsigned long length;
  float start(in unsigned long index);
  float end(in unsigned long index);
};
media . length

Returns the number of ranges in the object.

time = media . start(index)

Returns the time for the start of the range with the given index.

Throws an INDEX_SIZE_ERR if the index is out of range.

time = media . end(index)

Returns the time for the end of the range with the given index.

Throws an INDEX_SIZE_ERR if the index is out of range.

4.8.10.13 Event summary

The following events fire on media elements as part of the processing model described above:

Event name Interface Dispatched when... Preconditions
loadstart ProgressEvent [PROGRESS] The user agent begins looking for media data, as part of the resource selection algorithm. networkState equals NETWORK_LOADING
progress ProgressEvent [PROGRESS] The user agent is fetching media data. networkState equals NETWORK_LOADING
suspend ProgressEvent [PROGRESS] The user agent is intentionally not currently fetching media data, but does not have the entire media resource downloaded. networkState equals NETWORK_IDLE
load ProgressEvent [PROGRESS] The user agent finishes fetching the entire media resource. networkState equals NETWORK_LOADED
abort ProgressEvent [PROGRESS] The user agent stops fetching the media data before it is completely downloaded. error is an object with the code MEDIA_ERR_ABORTED. networkState equals either NETWORK_EMPTY or NETWORK_LOADED, depending on when the download was aborted.
error ProgressEvent [PROGRESS] An error occurs while fetching the media data. error is an object with the code MEDIA_ERR_NETWORK or higher. networkState equals either NETWORK_EMPTY or NETWORK_LOADED, depending on when the download was aborted.
emptied Event A media element whose networkState was previously not in the NETWORK_EMPTY state has just switched to that state (either because of a fatal error during load that's about to be reported, or because the load() method was invoked while the resource selection algorithm was already running, in which case it is fired synchronously during the load() method call). networkState is NETWORK_EMPTY; all the DOM attributes are in their initial states.
stalled ProgressEvent The user agent is trying to fetch media data, but data is unexpectedly not forthcoming. networkState is NETWORK_LOADING.
play Event Playback has begun. Fired after the play() method has returned. paused is newly false.
pause Event Playback has been paused. Fired after the pause method has returned. paused is newly true.
loadedmetadata Event The user agent has just determined the duration and dimensions of the media resource. readyState is newly equal to HAVE_METADATA or greater for the first time.
loadeddata Event The user agent can render the media data at the current playback position for the first time. readyState newly increased to HAVE_CURRENT_DATA or greater for the first time.
waiting Event Playback has stopped because the next frame is not available, but the user agent expects that frame to become available in due course. readyState is newly equal to or less than HAVE_CURRENT_DATA, and paused is false. Either seeking is true, or the current playback position is not contained in any of the ranges in buffered. It is possible for playback to stop for two other reasons without paused being false, but those two reasons do not fire this event: maybe playback ended, or playback stopped due to errors.
playing Event Playback has started. readyState is newly equal to or greater than HAVE_FUTURE_DATA, paused is false, seeking is false, or the current playback position is contained in one of the ranges in buffered.
canplay Event The user agent can resume playback of the media data, but estimates that if playback were to be started now, the media resource could not be rendered at the current playback rate up to its end without having to stop for further buffering of content. readyState newly increased to HAVE_FUTURE_DATA or greater.
canplaythrough Event The user agent estimates that if playback were to be started now, the media resource could be rendered at the current playback rate all the way to its end without having to stop for further buffering. readyState is newly equal to HAVE_ENOUGH_DATA.
seeking Event The seeking DOM attribute changed to true and the seek operation is taking long enough that the user agent has time to fire the event.
seeked Event The seeking DOM attribute changed to false.
timeupdate Event The current playback position changed as part of normal playback or in an especially interesting way, for example discontinuously.
ended Event Playback has stopped because the end of the media resource was reached. currentTime equals the end of the media resource; ended is true.
ratechange Event Either the defaultPlaybackRate or the playbackRate attribute has just been updated.
durationchange Event The duration attribute has just been updated.
volumechange Event Either the volume attribute or the muted attribute has changed. Fired after the relevant attribute's setter has returned.

4.8.11 The canvas element

Status: Implemented and widely deployed

Categories
Flow content.
Phrasing content.
Embedded content.
Contexts in which this element may be used:
Where embedded content is expected.
Content model:
Transparent.
Content attributes:
Global attributes
width
height
DOM interface:
interface HTMLCanvasElement : HTMLElement {
           attribute unsigned long width;
           attribute unsigned long height;

  DOMString toDataURL(optional in DOMString type, in any... args);

  Object getContext(in DOMString contextId);
};

The canvas element represents a resolution-dependent bitmap canvas, which can be used for rendering graphs, game graphics, or other visual images on the fly.

Authors should not use the canvas element in a document when a more suitable element is available. For example, it is inappropriate to use a canvas element to render a page heading: if the desired presentation of the heading is graphically intense, it should be marked up using appropriate elements (typically h1) and then styled using CSS and supporting technologies such as XBL.

When authors use the canvas element, they must also provide content that, when presented to the user, conveys essentially the same function or purpose as the bitmap canvas. This content may be placed as content of the canvas element. The contents of the canvas element, if any, are the element's fallback content.

In interactive visual media, if scripting is enabled for the canvas element, the canvas element represents an embedded element with a dynamically created image.

In non-interactive, static, visual media, if the canvas element has been previously painted on (e.g. if the page was viewed in an interactive visual medium and is now being printed, or if some script that ran during the page layout process painted on the element), then the canvas element represents embedded content with the current image and size. Otherwise, the element represents its fallback content instead.

In non-visual media, and in visual media if scripting is disabled for the canvas element, the canvas element represents its fallback content instead.

The canvas element has two attributes to control the size of the coordinate space: width and height. These attributes, when specified, must have values that are valid non-negative integers. The width attribute defaults to 300, and the height attribute defaults to 150.

The intrinsic dimensions of the canvas element equal the size of the coordinate space, with the numbers interpreted in CSS pixels. However, the element can be sized arbitrarily by a style sheet. During rendering, the image is scaled to fit this layout size.

Only one square appears to be drawn in the following example:

  // canvas is a reference to a <canvas> element
  var context = canvas.getContext('2d');
  context.fillRect(0,0,50,50);
  canvas.setAttribute('width', '300'); // clears the canvas
  context.fillRect(0,100,50,50);
  canvas.width = canvas.width; // clears the canvas
  context.fillRect(100,0,50,50); // only this square remains

To draw on the canvas, authors must first obtain a reference to a context using the getContext(contextId) method of the canvas element.

context = canvas . getContext(contextId)

Returns an object that exposes an API for drawing on the canvas.

Returns null if the given context ID is not supported.

This specification only defines one context, with the name "2d".

A future version of this specification will probably define a 3d context (probably based on the OpenGL ES API).


url = canvas . toDataURL( [ type, ... ])

Returns a data: URL for the image in the canvas.

The first argument, if provided, controls the type of the image to be returned (e.g. PNG or JPEG). The default is image/png; that type is also used if the given type isn't supported. The other arguments are specific to the type, and control the way that the image is generated, as given in the table below.

When trying to use types other than image/png, authors can check if the image was really returned in the requested format by checking to see if the returned string starts with one the exact strings "data:image/png," or "data:image/png;". If it does, the image is PNG, and thus the requested type was not supported. (The one exception to this is if the canvas has either no height or no width, in which case the result might simply be "data:,".)

Type Other arguments
image/jpeg The second argument, if it, must beIf it is not a number or is outside that range, the user agent must use its default value, as if the argument had been omitted.
4.8.11.1 The 2D context

Status: Implemented and widely deployed

When the getContext() method of a canvas element is invoked with 2d as the argument, a CanvasRenderingContext2D object is returned.

The 2D context represents a flat Cartesian surface whose origin (0,0) is at the top left corner, with the coordinate space having x values increasing when going right, and y values increasing when going down.

interface CanvasRenderingContext2D {

  // back-reference to the canvas
  readonly attribute HTMLCanvasElement canvas;

  // state
  void save(); // push state on state stack
  void restore(); // pop state stack and restore state

  // transformations (default transform is the identity matrix)
  void scale(in float x, in float y);
  void rotate(in float angle);
  void translate(in float x, in float y);
  void transform(in float m11, in float m12, in float m21, in float m22, in float dx, in float dy);
  void setTransform(in float m11, in float m12, in float m21, in float m22, in float dx, in float dy);

  // compositing
           attribute float globalAlpha; // (default 1.0)
           attribute DOMString globalCompositeOperation; // (default source-over)

  // colors and styles
           attribute any strokeStyle; // (default black)
           attribute any fillStyle; // (default black)
  CanvasGradient createLinearGradient(in float x0, in float y0, in float x1, in float y1);
  CanvasGradient createRadialGradient(in float x0, in float y0, in float r0, in float x1, in float y1, in float r1);
  CanvasPattern createPattern(in HTMLImageElement image, in DOMString repetition);
  CanvasPattern createPattern(in HTMLCanvasElement image, in DOMString repetition);
  CanvasPattern createPattern(in HTMLVideoElement image, in DOMString repetition);

  // line caps/joins
           attribute float lineWidth; // (default 1)
           attribute DOMString lineCap; // "butt", "round", "square" (default "butt")
           attribute DOMString lineJoin; // "round", "bevel", "miter" (default "miter")
           attribute float miterLimit; // (default 10)

  // shadows
           attribute float shadowOffsetX; // (default 0)
           attribute float shadowOffsetY; // (default 0)
           attribute float shadowBlur; // (default 0)
           attribute DOMString shadowColor; // (default transparent black)

  // rects
  void clearRect(in float x, in float y, in float w, in float h);
  void fillRect(in float x, in float y, in float w, in float h);
  void strokeRect(in float x, in float y, in float w, in float h);

  // path API
  void beginPath();
  void closePath();
  void moveTo(in float x, in float y);
  void lineTo(in float x, in float y);
  void quadraticCurveTo(in float cpx, in float cpy, in float x, in float y);
  void bezierCurveTo(in float cp1x, in float cp1y, in float cp2x, in float cp2y, in float x, in float y);
  void arcTo(in float x1, in float y1, in float x2, in float y2, in float radius);
  void rect(in float x, in float y, in float w, in float h);
  void arc(in float x, in float y, in float radius, in float startAngle, in float endAngle, in boolean anticlockwise);
  void fill();
  void stroke();
  void clip();
  boolean isPointInPath(in float x, in float y);

  // text
           attribute DOMString font; // (default 10px sans-serif)
           attribute DOMString textAlign; // "start", "end", "left", "right", "center" (default: "start")
           attribute DOMString textBaseline; // "top", "hanging", "middle", "alphabetic", "ideographic", "bottom" (default: "alphabetic")
  void fillText(in DOMString text, in float x, in float y, optional in float maxWidth);
  void strokeText(in DOMString text, in float x, in float y, optional in float maxWidth);
  TextMetrics measureText(in DOMString text);

  // drawing images
  void drawImage(in HTMLImageElement image, in float dx, in float dy, optional in float dw, in float dh);
  void drawImage(in HTMLImageElement image, in float sx, in float sy, in float sw, in float sh, in float dx, in float dy, in float dw, in float dh);
  void drawImage(in HTMLCanvasElement image, in float dx, in float dy, optional in float dw, in float dh);
  void drawImage(in HTMLCanvasElement image, in float sx, in float sy, in float sw, in float sh, in float dx, in float dy, in float dw, in float dh);
  void drawImage(in HTMLVideoElement image, in float dx, in float dy, optional in float dw, in float dh);
  void drawImage(in HTMLVideoElement image, in float sx, in float sy, in float sw, in float sh, in float dx, in float dy, in float dw, in float dh);

  // pixel manipulation
  ImageData createImageData(in float sw, in float sh);
  ImageData createImageData(in ImageData imagedata);
  ImageData getImageData(in float sx, in float sy, in float sw, in float sh);
  void putImageData(in ImageData imagedata, in float dx, in float dy, optional in float dirtyX, in float dirtyY, in float dirtyWidth, in float dirtyHeight);
};

interface CanvasGradient {
  // opaque object
  void addColorStop(in float offset, in DOMString color);
};

interface CanvasPattern {
  // opaque object
};

interface TextMetrics {
  readonly attribute float width;
};

interface ImageData {
  readonly attribute unsigned long width;
  readonly attribute unsigned long height;
  readonly attribute CanvasPixelArray data;
};

interface CanvasPixelArray {
  readonly attribute unsigned long length;
  getter octet (in unsigned long index);
  setter void (in unsigned long index, in octet value);
};
context . canvas

Returns the canvas element.

4.8.11.1.1 The canvas state

Each context maintains a stack of drawing states. Drawing states consist of:

The current path and the current bitmap are not part of the drawing state. The current path is persistent, and can only be reset using the beginPath() method. The current bitmap is a property of the canvas, not the context.

context . save()

Pushes the current state onto the stack.

context . restore()

Pops the top state on the stack, restoring the context to that state.

4.8.11.1.2 Transformations

Status: Awaiting implementation feedback

The transformation matrix is applied to coordinates when creating shapes and paths.

context . scale(x, y)

Changes the transformation matrix to apply a scaling transformation with the given characteristics.

context . rotate(angle)

Changes the transformation matrix to apply a rotation transformation with the given characteristics.

context . translate(x, y)

Changes the transformation matrix to apply a translation transformation with the given characteristics.

context . transform(m11, m12, m21, m22, dx, dy)

Changes the transformation matrix to apply the matrix given by the arguments as described below.

context . setTransform(m11, m12, m21, m22, dx, dy)

Changes the transformation matrix to the matrix given by the arguments as described below.

m11 m21 dx
m12 m22 dy
0 0 1
4.8.11.1.3 Compositing

Status: Awaiting implementation feedback

context . globalAlpha [ = value ]

Returns the current alpha value applied to rendering operations.

Can be set, to change the alpha value. Values outside of the range 0.0 .. 1.0 are ignored.

context . globalCompositeOperation [ = value ]

Returns the current composition operation, from the list below.

Can be set, to change the composition operation. Unknown values are ignored.

source-atop
A atop B. Display the source image wherever both images are opaque. Display the destination image wherever the destination image is opaque but the source image is transparent. Display transparency elsewhere.
source-in
A in B. Display the source image wherever both the source image and destination image are opaque. Display transparency elsewhere.
source-out
A out B. Display the source image wherever the source image is opaque and the destination image is transparent. Display transparency elsewhere.
source-over (default)
A over B. Display the source image wherever the source image is opaque. Display the destination image elsewhere.
destination-atop
B atop A. Same as source-atop but using the destination image instead of the source image and vice versa.
destination-in
B in A. Same as source-in but using the destination image instead of the source image and vice versa.
destination-out
B out A. Same as source-out but using the destination image instead of the source image and vice versa.
destination-over
B over A. Same as source-over but using the destination image instead of the source image and vice versa.
lighter
A plus B. Display the sum of the source image and destination image, with color values approaching 1 as a limit.
copy
A (B is ignored). Display the source image instead of the destination image.
xor
A xor B. Exclusive OR of the source image and destination image.
4.8.11.1.4 Colors and styles

Status: Awaiting implementation feedback

context . strokeStyle [ = value ]

Returns the current style used for stroking shapes.

Can be set, to change the stroke style.

The style can be either a string containing a CSS color, or a CanvasGradient or CanvasPattern object. Invalid values are ignored.

context . fillStyle [ = value ]

Returns the current style used for filling shapes.

Can be set, to change the fill style.

The style can be either a string containing a CSS color, or a CanvasGradient or CanvasPattern object. Invalid values are ignored.


There are two types of gradients, linear gradients and radial gradients, both represented by objects implementing the opaque CanvasGradient interface.

Once a gradient has been created (see below), stops are placed along it to define how the colors are distributed along the gradient.

gradient . addColorStop(offset, color)

Adds a color stop with the given color to the gradient at the given offset. 0.0 is the offset at one end of the gradient, 1.0 is the offset at the other end.

Throws an INDEX_SIZE_ERR exception if the offset it out of range. Throws a SYNTAX_ERR exception if the color cannot be parsed.

gradient = context . createLinearGradient(x0, y0, x1, y1)

Returns a CanvasGradient object that represents a linear gradient that paints along the line given by the coordinates represented by the arguments.

If any of the arguments are not finite numbers, throws a NOT_SUPPORTED_ERR exception.

gradient = context . createRadialGradient(x0, y0, r0, x1, y1, r1)

Returns a CanvasGradient object that represents a radial gradient that paints along the cone given by the circles represented by the arguments.

If any of the arguments are not finite numbers, throws a NOT_SUPPORTED_ERR exception. If either of the radii are negative throws an INDEX_SIZE_ERR exception.


Patterns are represented by objects implementing the opaque CanvasPattern interface.

pattern = context . createPattern(image, repetition)

Returns a CanvasPattern object that uses the given image and repeats in the direction(s) given by the repetition argument.

The allowed values for repeat are repeat (both directions), repeat-x (horizontal only), repeat-y (vertical only), and no-repeat (neither). If the repetition argument is empty or null, the value repeat is used.

If the first argument isn't an img, canvas, or video element, throws a TYPE_MISMATCH_ERR exception. If the image is not fully decoded yet, or has no image data, throws an INVALID_STATE_ERR exception. If the second argument isn't one of the allowed values, throws a SYNTAX_ERR exception.

4.8.11.1.5 Line styles

Status: Awaiting implementation feedback

context . lineWidth [ = value ]

Returns the current line width.

Can be set, to change the line width. Values that are not finite values greater than zero are ignored.

context . lineCap [ = value ]

Returns the current line cap style.

Can be set, to change the line cap style.

The possible line cap styles are butt, round, and square. Other values are ignored.

context . lineJoin [ = value ]

Returns the current line join style.

Can be set, to change the line join style.

The possible line join styles are bevel, round, and miter. Other values are ignored.

context . miterLimit [ = value ]

Returns the current miter limit ratio.

Can be set, to change the miter limit ratio. Values that are not finite values greater than zero are ignored.

4.8.11.1.6 Shadows

Status: Last call for comments

All drawing operations are affected by the four global shadow attributes.

context . shadowColor [ = value ]

Returns the current shadow color.

Can be set, to change the shadow color. Values that cannot be parsed as CSS colors are ignored.

context . shadowOffsetX [ = value ]
context . shadowOffsetY [ = value ]

Returns the current shadow offset.

Can be set, to change the shadow offset. Values that are not finite numbers are ignored.

context . shadowBlur [ = value ]

Returns the current level of blur applied to shadows.

Can be set, to change the blur level. Values that are not finite numbers greater than or equal to zero are ignored.

4.8.11.1.7 Simple shapes (rectangles)

There are three methods that immediately draw rectangles to the bitmap. They each take four arguments; the first two give the x and y coordinates of the top left of the rectangle, and the second two give the width w and height h of the rectangle, respectively.

context . clearRect(x, y, w, h)

Clears all pixels on the canvas in the given rectangle to transparent black.

context . fillRect(x, y, w, h)

Paints the given rectangle onto the canvas, using the current fill style.

context . strokeRect(x, y, w, h)

Paints the box that outlines the given rectangle onto the canvas, using the current stroke style.

4.8.11.1.8 Complex shapes (paths)

The context always has a current path. There is only one current path, it is not part of the drawing state.

A path has a list of zero or more subpaths. Each subpath consists of a list of one or more points, connected by straight or curved lines, and a flag indicating whether the subpath is closed or not. A closed subpath is one where the last point of the subpath is connected to the first point of the subpath by a straight line. Subpaths with fewer than two points are ignored when painting the path.

context . beginPath()

Resets the current path.

context . moveTo(x, y)

Creates a new subpath with the given point.

context . closePath()

Marks the current subpath as closed, and starts a new subpath with a point the same as the start and end of the newly closed subpath.

context . lineTo(x, y)

Adds the given point to the current subpath, connected to the previous one by a straight line.

context . quadraticCurveTo(cpx, cpy, x, y)

Adds the given point to the current path, connected to the previous one by a quadratic Bézier curve with the given control point.

context . bezierCurveTo(cp1x, cp1y, cp2x, cp2y, x, y)

Adds the given point to the current path, connected to the previous one by a cubic Bézier curve with the given control points.

context . arcTo(x1, y1, x2, y2, radius)

Adds a point to the current path, connected to the previous one by a straight line, then adds a second point to the current path, connected to the previous one by an arc whose properties are described by the arguments.

Throws an INDEX_SIZE_ERR exception if the given radius is negative.

context . arc(x, y, radius, startAngle, endAngle, anticlockwise)

Adds points to the subpath such that the arc described by the circumference of the circle described by the arguments, starting at the given start angle and ending at the given end angle, going in the given direction, is added to the path, connected to the previous point by a straight line.

Throws an INDEX_SIZE_ERR exception if the given radius is negative.

context . rect(x, y, w, h)

Adds a new closed subpath to the path, representing the given rectangle.

context . fill()

Fills the subpaths with the current fill style.

context . stroke()

Strokes the subpaths with the current stroke style.

context . clip()

Further constrains the clipping region to the given path.

context . isPointInPath(x, y)

Returns true if the given point is in the current path.

4.8.11.1.9 Text

Status: Last call for comments

context . font [ = value ]

Returns the current font settings.

Can be set, to change the font. The syntax is the same as for the CSS 'font' property; values that cannot be parsed as CSS font values are ignored.

Relative keywords and lengths are computed relative to the font of the canvas element.

context . textAlign [ = value ]

Returns the current text alignment settings.

Can be set, to change the alignment. The possible values are start, end, left, right, and center. The default is start. Other values are ignored.

context . textBaseline [ = value ]

Returns the current baseline alignment settings.

Can be set, to change the baseline alignment. The possible values and their meanings are given below. The default is alphabetic. Other values are ignored.

context . fillText(text, x, y [, maxWidth ] )
context . strokeText(text, x, y [, maxWidth ] )

Fills or strokes (respectively) the given text at the given position. If a maximum width is provided, the text will be scaled to fit that width if necessary.

metrics = context . measureText(text)

Returns a TextMetrics object with the metrics of the given text in the current font.

metrics . width

Returns the advance width of the text that was passed to the measureText() method.

The textBaseline attribute's allowed keywords correspond to alignment points in the font:

The top of the em square is
  roughly at the top of the glyphs in a font, the hanging baseline is
  where some glyphs like आ are anchored, the middle is half-way
  between the top of the em square and the bottom of the em square,
  the alphabetic baseline is where characters like Á, ÿ,
  f, and Ω are anchored, the ideographic baseline is
  where glyphs like 私 and 達 are anchored, and the bottom
  of the em square is roughly at the bottom of the glyphs in a
  font. The top and bottom of the bounding box can be far from these
  baselines, due to glyphs extending far outside the em square.

The keywords map to these alignment points as follows:

top
The top of the em square
hanging
The hanging baseline
middle
The middle of the em square
alphabetic
The alphabetic baseline
ideographic
The ideographic baseline
bottom
The bottom of the em square

A future version of the 2D context API may provide a way to render fragments of documents, rendered using CSS, straight to the canvas. This would be provided in preference to a dedicated way of doing multiline layout.

4.8.11.1.10 Images

Status: Awaiting implementation feedback

To draw images onto the canvas, the drawImage method can be used.

This method can be invoked with three different sets of arguments:

Each of those three can take either an HTMLImageElement, an HTMLCanvasElement, or an HTMLVideoElement for the image argument.

context . drawImage(image, dx, dy)
context . drawImage(image, dx, dy, dw, dh)
context . drawImage(image, sx, sy, sw, sh, dx, dy, dw, dh)

Draws the given image onto the canvas. The arguments are interpreted as follows:

The sx and sy parameters give the x and y coordinates of the source rectangle; the sw and sh arguments give the width and height of the source rectangle; the dx and dy give the x and y coordinates of the destination rectangle; and the dw and dh arguments give the width and height of the destination rectangle.

If the first argument isn't an img, canvas, or video element, throws a TYPE_MISMATCH_ERR exception. If the image is not fully decoded yet, or has no image data, throws an INVALID_STATE_ERR exception. If the second argument isn't one of the allowed values, throws a SYNTAX_ERR exception.

4.8.11.1.11 Pixel manipulation

Status: Awaiting implementation feedback

imagedata = context . createImageData(sw, sh)

Returns an ImageData object with the given dimensions in CSS pixels (which might map to a different number of actual device pixels exposed by the object itself). All the pixels in the returned object are transparent black.

imagedata = context . createImageData(imagedata)

Returns an ImageData object with the same dimensions as the argument. All the pixels in the returned object are transparent black.

Throws a NOT_SUPPORTED_ERR exception if the argument is null.

imagedata = context . getImageData(sx, sy, sw, sh)

Returns an ImageData object containing the image data for the given rectangle of the canvas.

Throws a NOT_SUPPORTED_ERR exception if any of the arguments are not finite. Throws an INDEX_SIZE_ERR exception if the either of the width or height arguments are zero.

imagedata . width
imagedata . height

Returns the actual dimensions of the data in the ImageData object, in device pixels.

imagedata . data

Returns the one-dimensional array containing the data.

context . putImageData(imagedata, dx, dy [, dirtyX, dirtyY, dirtyWidth, dirtyHeight ])

Paints the data from the given ImageData object onto the canvas. If a dirty rectangle is provided, only the pixels from that rectangle are painted.

The globalAlpha and globalCompositeOperation attributes, as well as the shadow attributes, are ignored for the purposes of this method call; pixels in the canvas are replaced wholesale, with no composition, alpha blending, no shadows, etc.

If the first argument isn't an ImageData object, throws a TYPE_MISMATCH_ERR exception. Throws a NOT_SUPPORTED_ERR exception if any of the other arguments are not finite.

The data returned by getImageData() is at the resolution of the canvas backing store, which is likely to not be one device pixel to each CSS pixel if the display used is a high resolution display.

In the following example, the script generates an ImageData object so that it can draw onto it.

// canvas is a reference to a <canvas> element
var context = canvas.getContext('2d');

// create a blank slate
var data = context.createImageData(canvas.width, canvas.height);

// create some plasma
FillPlasma(data, 'green'); // green plasma

// add a cloud to the plasma
AddCloud(data, data.width/2, data.height/2); // put a cloud in the middle

// paint the plasma+cloud on the canvas
context.putImageData(data, 0, 0);

// support methods
function FillPlasma(data, color) { ... }
function AddCloud(data, x, y) { ... }

Here is an example of using getImageData() and putImageData() to implement an edge detection filter.

<!DOCTYPE HTML>
<html>
 <head>
  <title>Edge detection demo</title>
  <script>
   var image = new Image();
   function init() {
     image.onload = demo;
     image.src = "image.jpeg";
   }
   function demo() {
     var canvas = document.getElementsByTagName('canvas')[0];
     var context = canvas.getContext('2d');

     // draw the image onto the canvas
     context.drawImage(image, 0, 0);

     // get the image data to manipulate
     var input = context.getImageData(0, 0, canvas.width, canvas.height);

     // get an empty slate to put the data into
     var output = context.createImageData(canvas.width, canvas.height);

     // alias some variables for convenience
     // notice that we are using input.width and input.height here
     // as they might not be the same as canvas.width and canvas.height
     // (in particular, they might be different on high-res displays)
     var w = input.width, h = input.height;
     var inputData = input.data;
     var outputData = output.data;

     // edge detection
     for (var y = 1; y < h-1; y += 1) {
       for (var x = 1; x < w-1; x += 1) {
         for (var c = 0; c < 3; c += 1) {
           var i = (y*w + x)*4 + c;
           outputData[i] = 127 + -inputData[i - w*4 - 4] -   inputData[i - w*4] - inputData[i - w*4 + 4] +
                                 -inputData[i - 4]       + 8*inputData[i]       - inputData[i + 4] +
                                 -inputData[i + w*4 - 4] -   inputData[i + w*4] - inputData[i + w*4 + 4];
         }
         outputData[(y*w + x)*4 + 3] = 255; // alpha
       }
     }

     // put the image data back after manipulation
     context.putImageData(output, 0, 0);
   }
  </script>
 </head>
 <body onload="init()">
  <canvas></canvas>
 </body>
</html>

4.8.12 The map element

Status: Last call for comments

Categories
Flow content.
When the element only contains phrasing content: phrasing content.
Contexts in which this element may be used:
Where phrasing content is expected.
Content model:
Transparent.
Content attributes:
Global attributes
name
DOM interface:
interface HTMLMapElement : HTMLElement {
           attribute DOMString name;
  readonly attribute HTMLCollection areas;
  readonly attribute HTMLCollection images;
};

The map element, in conjunction with any area element descendants, defines an image map. The element represents its children.

The name attribute gives the map a name so that it can be referenced. The attribute must be present and must have a non-empty value with no space characters. If the id attribute is also specified, both attributes must have the same value.

map . areas

Returns an HTMLCollection of the area elements in the map.

map . images

Returns an HTMLCollection of the img and object elements that use the map.

4.8.13 The area element

Status: Last call for comments

Categories
Flow content.
Phrasing content.
Contexts in which this element may be used:
Where phrasing content is expected, but only if there is a map element ancestor.
Content model:
Empty.
Content attributes:
Global attributes
alt
coords
shape
href
target
ping
rel
media
hreflang
type
DOM interface:
interface HTMLAreaElement : HTMLElement {
           attribute DOMString alt;
           attribute DOMString coords;
           attribute DOMString shape;
  stringifier attribute DOMString href;
           attribute DOMString target;
           attribute DOMString ping;
           attribute DOMString rel;
  readonly attribute DOMTokenList relList;
           attribute DOMString media;
           attribute DOMString hreflang;
           attribute DOMString type;

  // URL decomposition attributes
           attribute DOMString protocol;
           attribute DOMString host;
           attribute DOMString hostname;
           attribute DOMString port;
           attribute DOMString pathname;
           attribute DOMString search;
           attribute DOMString hash;
};

The area element represents either a hyperlink with some text and a corresponding area on an image map, or a dead area on an image map.

If the area element has an href attribute, then the area element represents a hyperlink. In this case, the alt attribute must be present. It specifies the text of the hyperlink. Its value must be text that, when presented with the texts specified for the other hyperlinks of the image map, and with the alternative text of the image, but without the image itself, provides the user with the same kind of choice as the hyperlink would when used without its text but with its shape applied to the image. The alt attribute may be left blank if there is another area element in the same image map that points to the same resource and has a non-blank alt attribute.

If the area element has no href attribute, then the area represented by the element cannot be selected, and the alt attribute must be omitted.

In both cases, the shape and coords attributes specify the area.

The shape attribute is an enumerated attribute. The following table lists the keywords defined for this attribute. The states given in the first cell of the rows with keywords give the states to which those keywords map.

State Keywords
Circle state circle
Default state default
Polygon state poly
Rectangle state rect

The attribute may be omitted. The missing value default is the rectangle state.

The coords attribute must, if specified, contain a valid list of integers. This attribute gives the coordinates for the shape described by the shape attribute.

In the circle state, area elements must have a coords attribute present, with three integers, the last of which must be non-negative. The first integer must be the distance in CSS pixels from the left edge of the image to the center of the circle, the second integer must be the distance in CSS pixels from the top edge of the image to the center of the circle, and the third integer must be the radius of the circle, again in CSS pixels.

In the default state state, area elements must not have a coords attribute. (The area is the whole image.)

In the polygon state, area elements must have a coords attribute with at least six integers, and the number of integers must be even. Each pair of integers must represent a coordinate given as the distances from the left and the top of the image in CSS pixels respectively, and all the coordinates together must represent the points of the polygon, in order.

In the rectangle state, area elements must have a coords attribute with exactly four integers, the first of which must be less than the third, and the second of which must be less than the fourth. The four points must represent, respectively, the distance from the left edge of the image to the left side of the rectangle, the distance from the top edge to the top side, the distance from the left edge to the right side, and the distance from the top edge to the bottom side, all in CSS pixels.

The target, ping, rel, media, hreflang, and type attributes must be omitted if the href attribute is not present.

4.8.14 Image maps

Status: Last call for comments

An image map allows geometric areas on an image to be associated with hyperlinks.

An image, in the form of an img element or an object element representing an image, may be associated with an image map (in the form of a map element) by specifying a usemap attribute on the img or object element. The usemap attribute, if specified, must be a valid hash-name reference to a map element.

Consider an image that looks as follows:

A line with four shapes in it, equally spaced: a red hollow box, a green circle, a blue triangle, and a yellow four-pointed star.

If we wanted just the colored areas to be clickable, we could do it as follows:

<p>
 Please select a shape:
 <img src="shapes.png" usemap="#shapes"
      alt="Four shapes are available: a red hollow box, a green circle, a blue triangle, and a yellow four-pointed star.">
 <map name="shapes">
  <area shape=rect coords="50,50,100,100"> <!-- the hole in the red box -->
  <area shape=rect coords="25,25,125,125" href="red.html" alt="Red box.">
  <area shape=circle coords="200,75,50" href="green.html" alt="Green circle.">
  <area shape=poly coords="325,25,262,125,388,125" href="blue.html" alt="Blue triangle.">
  <area shape=poly coords="450,25,435,60,400,75,435,90,450,125,465,90,500,75,465,60"
        href="yellow.html" alt="Yellow star.">
 </map>
</p>

4.8.15 MathML

Status: Last call for comments

The math element from the MathML namespace falls into the embedded content category for the purposes of the content models in this specification.

4.8.16 SVG

Status: Last call for comments

The svg element from the SVG namespace falls into the embedded content, phrasing content, and flow content categories for the purposes of the content models in this specification.

When the SVG foreignObject element contains elements from the HTML namespace, such elements must all be flow content. [SVG]

The content model for title elements in the SVG namespace inside HTML documents is phrasing content. (This further constrains the requirements given in the SVG specification.)

4.8.17 Dimension attributes

Status: Last call for comments

Author requirementswidth and height attributes on img, iframe, embed, object, video, and, when their type attribute is in the Image Button state, input elements may be specified to give the dimensions of the visual content of the element (the width and height respectively, relative to the nominal direction of the output medium), in CSS pixels. The attributes, if specified, must have values that are valid non-negative integers.

The specified dimensions given may differ from the dimensions specified in the resource itself, since the resource may have a resolution that differs from the CSS pixel resolution. (On screens, CSS pixels have a resolution of 96ppi, but in general the CSS pixel resolution depends on the reading distance.) If both attributes are specified, then one of the following statements must be true:

The target ratio is the ratio of the intrinsic width to the intrinsic height in the resource. The specified width and specified height are the values of the width and height attributes respectively.

The two attributes must be omitted if the resource in question does not have both an intrinsic width and an intrinsic height.

If the two attributes are both zero, it indicates that the element is not intended for the user (e.g. it might be a part of a service to count page views).

The dimension attributes are not intended to be used to stretch the image.

4.9 Tabular data

Status: Last call for comments

4.9.1 Introduction

This section is non-normative.

...examples, how to write tables accessibly, a brief mention of the table model, etc...

4.9.2 The table element

Status: Last call for comments

Categories
Flow content.
Contexts in which this element may be used:
Where flow content is expected.
Content model:
In this order: optionally a caption element, followed by either zero or more colgroup elements, followed optionally by a thead element, followed optionally by a tfoot element, followed by either zero or more tbody elements or one or more tr elements, followed optionally by a tfoot element (but there can only be one tfoot element child in total).
Content attributes:
Global attributes
summary (but see prose)
DOM interface:
interface HTMLTableElement : HTMLElement {
           attribute HTMLTableCaptionElement caption;
  HTMLElement createCaption();
  void deleteCaption();
           attribute HTMLTableSectionElement tHead;
  HTMLElement createTHead();
  void deleteTHead();
           attribute HTMLTableSectionElement tFoot;
  HTMLElement createTFoot();
  void deleteTFoot();
  readonly attribute HTMLCollection tBodies;
  HTMLElement createTBody();
  readonly attribute HTMLCollection rows;
  HTMLElement insertRow(optional in long index);
  void deleteRow(in long index);
};

The table element represents data with more than one dimension, in the form of a table.

Tables must not be used as layout aids. Historically, some Web authors have misused tables in HTML as a way to control their page layout. This usage is non-conforming, because tools attempting to extract tabular data from such documents would obtain very confusing results. In particular, users of accessibility tools like screen readers are likely to find it very difficult to navigate pages with tables used for layout.

There are a variety of alternatives to using HTML tables for layout, primarily using CSS positioning and the CSS table model.

Tables have rows and columns given by their descendants. A table must not have an empty row or column, as described in the description of the

For tables that consist of more than just a grid of cells with headers in the first row and headers in the first column, and for any table in general where the reader might have difficulty understanding the content, authors should include explanatory information introducing the table. This information is useful for all users, but is especially useful for users who cannot see the table, e.g. users of screen readers.

Such explanatory information should introduce the purpose of the table, outline its basic cell structure, highlight any trends or patterns, and generally teach the user how to use the table.

For instance, the following table:

Characteristics with positive and negative sides
Negative Characteristic Positive
Sad Mood Happy
Failing Grade Passing

...might benefit from a description explaining to the way the table is laid out, something like "Characteristics are given in the second column, with the negative side in the left column and the positive side in the right column".

There are a variety of ways to include this information, such as:

In prose, surrounding the table
<p>In the following table, characteristics are given in the second
column, with the negative side in the left column and the positive
side in the right column.</p>
<table>
 <caption>Characteristics with positive and negative sides</caption>
 <thead>
  <tr>
   <th id="n"> Negative
   <th> Characteristic
   <th> Positive
 <tbody>
  <tr>
   <td headers="n r1"> Sad
   <th id="r1"> Mood
   <td> Happy
  <tr>
   <td headers="n r2"> Failing
   <th id="r2"> Grade
   <td> Passing
</table>
In the table's caption
<table>
 <caption>
  <strong>Characteristics with positive and negative sides.</strong>
  <p>Characteristics are given in the second column, with the
  negative side in the left column and the positive side in the right
  column.</p>
 </caption>
 <thead>
  <tr>
   <th id="n"> Negative
   <th> Characteristic
   <th> Positive
 <tbody>
  <tr>
   <td headers="n r1"> Sad
   <th id="r1"> Mood
   <td> Happy
  <tr>
   <td headers="n r2"> Failing
   <th id="r2"> Grade
   <td> Passing
</table>
In the table's caption, in a details element
<table>
 <caption>
  <strong>Characteristics with positive and negative sides.</strong>
  <details>
   <legend>Help</legend>
   <p>Characteristics are given in the second column, with the
   negative side in the left column and the positive side in the right
   column.</p>
  </details>
 </caption>
 <thead>
  <tr>
   <th id="n"> Negative
   <th> Characteristic
   <th> Positive
 <tbody>
  <tr>
   <td headers="n r1"> Sad
   <th id="r1"> Mood
   <td> Happy
  <tr>
   <td headers="n r2"> Failing
   <th id="r2"> Grade
   <td> Passing
</table>
Next to the table, in the same figure
<figure>
 <legend>Characteristics with positive and negative sides</legend>
 <p>Characteristics are given in the second
 column, with the negative side in the left column and the positive
 side in the right column.</p>
 <table>
  <thead>
   <tr>
    <th id="n"> Negative
    <th> Characteristic
    <th> Positive
  <tbody>
   <tr>
    <td headers="n r1"> Sad
    <th id="r1"> Mood
    <td> Happy
   <tr>
    <td headers="n r2"> Failing
    <th id="r2"> Grade
    <td> Passing
 </table>
<figure>
Next to the table, in a figure's legend
<figure>
 <legend>
  <strong>Characteristics with positive and negative sides</strong>
  <p>Characteristics are given in the second
  column, with the negative side in the left column and the positive
  side in the right column.</p>
 </legend>
 <table>
  <thead>
   <tr>
    <th id="n"> Negative
    <th> Characteristic
    <th> Positive
  <tbody>
   <tr>
    <td headers="n r1"> Sad
    <th id="r1"> Mood
    <td> Happy
   <tr>
    <td headers="n r2"> Failing
    <th id="r2"> Grade
    <td> Passing
 </table>
<figure>

Authors may also use other techniques, or combinations of the above techniques, as appropriate.

The summary attribute on table elements was suggested in earlier versions of the language as a technique for providing explanatory text for complex tables for users of screen readers. One of the techniques described above should be used instead.

In particular, authors are encouraged to consider whether their explanatory text for tables is likely to be useful to the visually impaired: if their text would not be useful, then it is best to not include a summary attribute. Similarly, if their explanatory text could help someone who is not visually impaired, e.g. someone who is seeing the table for the first time, then the text would be more useful before the table or in the caption. For example, describing the conclusions of the data in a table is useful to everyone; explaining how to read the table, if not obvious from the headers alone, is useful to everyone; describing the structure of the table, if it is easy to grasp visually, may not be useful to everyone, but it might also not be useful to users who can quickly navigate the table with an accessibility tool.

table . caption [ = value ]

Returns the table's caption element.

Can be set, to replace the caption element. If the new value is not a caption element, throws a HIERARCHY_REQUEST_ERR exception.

caption = table . createCaption()

Ensures the table has a caption element, and returns it.

table . deleteCaption()

Ensures the table does not have a caption element.

table . tHead [ = value ]

Returns the table's thead element.

Can be set, to replace the thead element. If the new value is not a thead element, throws a HIERARCHY_REQUEST_ERR exception.

thead = table . createTHead()

Ensures the table has a thead element, and returns it.

table . deleteTHead()

Ensures the table does not have a thead element.

table . tFoot [ = value ]

Returns the table's tfoot element.

Can be set, to replace the tfoot element. If the new value is not a tfoot element, throws a HIERARCHY_REQUEST_ERR exception.

tfoot = table . createTFoot()

Ensures the table has a tfoot element, and returns it.

table . deleteTFoot()

Ensures the table does not have a tfoot element.

table . tBodies

Returns an HTMLCollection of the tbody elements of the table.

tbody = table . createTBody()

Creates a tbody element, inserts it into the table, and returns it.

table . rows

Returns an HTMLCollection of the tr elements of the table.

tr = table . insertRow(index)

Creates a tr element, along with a tbody if required, inserts them into the table at the position given by the argument, and returns the tr.

The position is relative to the rows in the table. The index −1 is equivalent to inserting at the end of the table.

If the given position is less than −1 or greater than the number of rows, throws an INDEX_SIZE_ERR exception.

table . deleteRow(index)

Removes the tr element with the given position in the table.

The position is relative to the rows in the table. The index −1 is equivalent to deleting the last row of the table.

If the given position is less than −1 or greater than the index of the last row, or if there are no rows, throws an INDEX_SIZE_ERR exception.

4.9.3 The caption element

Status: Implemented and widely deployed

Categories
None.
Contexts in which this element may be used:
As the first element child of a table element.
Content model:
Flow content, but with no descendant table elements.
Content attributes:
Global attributes
DOM interface:
interface HTMLTableCaptionElement : HTMLElement {};

The caption element represents the title of the table that is its parent, if it has a parent and that is a table element.

When a table element is in a figure element alone but for the figure's legend, the caption element should be omitted in favor of the legend.

A caption can introduce context for a table, making it significantly easier to understand.

Consider, for instance, the following table:

1 2 3 4 5 6
1 2 3 4 5 6 7
2 3 4 5 6 7 8
3 4 5 6 7 8 9
4 5 6 7 8 9 10
5 6 7 8 9 10 11
6 7 8 9 10 11 12

In the abstract, this table is not clear. However, with a caption giving the table's number (for reference in the main prose) and explaining its use, it makes more sense:

<caption>
<p>Table 1.
<p>This table shows the total score obtained from rolling two
six-sided dice. The first row represents the value of the first die,
the first column the value of the second die. The total is given in
the cell that corresponds to the values of the two dice.
</caption>

This provides the user with more context:

Table 1.

This table shows the total score obtained from rolling two six-sided dice. The first row represents the value of the first die, the first column the value of the second die. The total is given in the cell that corresponds to the values of the two dice.

1 2 3 4 5 6
1 2 3 4 5 6 7
2 3 4 5 6 7 8
3 4 5 6 7 8 9
4 5 6 7 8 9 10
5 6 7 8 9 10 11
6 7 8 9 10 11 12

4.9.4 The colgroup element

Status: Implemented and widely deployed

Categories
None.
Contexts in which this element may be used:
As a child of a table element, after any caption elements and before any thead, tbody, tfoot, and tr elements.
Content model:
Zero or more col elements.
Content attributes:
Global attributes
span
DOM interface:
interface HTMLTableColElement : HTMLElement {
           attribute unsigned long span;
};

The colgroup element represents a group of one or more columns in the table that is its parent, if it has a parent and that is a table element.

If the colgroup element contains no col elements, then the element may have a span content attribute specified, whose value must be a valid non-negative integer greater than zero.

4.9.5 The col element

Status: Implemented and widely deployed

Categories
None.
Contexts in which this element may be used:
As a child of a colgroup element that doesn't have a span attribute.
Content model:
Empty.
Content attributes:
Global attributes
span
DOM interface:

HTMLTableColElement, same as for colgroup elements. This interface defines one member, span.

If a col element has a parent and that is a colgroup element that itself has a parent that is a table element, then the col element represents one or more columns in the column group represented by that colgroup.

The element may have a span content attribute specified, whose value must be a valid non-negative integer greater than zero.

4.9.6 The tbody element

Status: Implemented and widely deployed

Categories
None.
Contexts in which this element may be used:
As a child of a table element, after any caption, colgroup, and thead elements, but only if there are no tr elements that are children of the table element.
Content model:
Zero or more tr elements
Content attributes:
Global attributes
DOM interface:
interface HTMLTableSectionElement : HTMLElement {
  readonly attribute HTMLCollection rows;
  HTMLElement insertRow(optional in long index);
  void deleteRow(in long index);
};

The HTMLTableSectionElement interface is also used for thead and tfoot elements.

The tbody element represents a block of rows that consist of a body of data for the parent table element, if the tbody element has a parent and it is a table.

tbody . rows

Returns an HTMLCollection of the tr elements of the table section.

tr = tbody . insertRow( [ index ] )

Creates a tr element, inserts it into the table section at the position given by the argument, and returns the tr.

The position is relative to the rows in the table section. The index −1, which is the default if the argument is omitted, is equivalent to inserting at the end of the table section.

If the given position is less than −1 or greater than the number of rows, throws an INDEX_SIZE_ERR exception.

tbody . deleteRow(index)

Removes the tr element with the given position in the table section.

The position is relative to the rows in the table section. The index −1 is equivalent to deleting the last row of the table section.

If the given position is less than −1 or greater than the index of the last row, or if there are no rows, throws an INDEX_SIZE_ERR exception.

4.9.7 The thead element

Status: Implemented and widely deployed

Categories
None.
Contexts in which this element may be used:
As a child of a table element, after any caption, and colgroup elements and before any tbody, tfoot, and tr elements, but only if there are no other thead elements that are children of the table element.
Content model:
Zero or more tr elements
Content attributes:
Global attributes
DOM interface:
HTMLTableSectionElement, as defined for tbody elements.

The thead element represents the block of rows that consist of the column labels (headers) for the parent table element, if the thead element has a parent and it is a table.

4.9.8 The tfoot element

Status: Implemented and widely deployed

Categories
None.
Contexts in which this element may be used:
As a child of a table element, after any caption, colgroup, and thead elements and before any tbody and tr elements, but only if there are no other tfoot elements that are children of the table element.
As a child of a table element, after any caption, colgroup, thead, tbody, and tr elements, but only if there are no other tfoot elements that are children of the table element.
Content model:
Zero or more tr elements
Content attributes:
Global attributes
DOM interface:
HTMLTableSectionElement, as defined for tbody elements.

The tfoot element represents the block of rows that consist of the column summaries (footers) for the parent table element, if the tfoot element has a parent and it is a table.

4.9.9 The tr element

Status: Implemented and widely deployed

Categories
None.
Contexts in which this element may be used:
As a child of a thead element.
As a child of a tbody element.
As a child of a tfoot element.
As a child of a table element, after any caption, colgroup, and thead elements, but only if there are no tbody elements that are children of the table element.
Content model:
When the parent node is a thead element: Zero or more th elements
Otherwise: Zero or more td or th elements
Content attributes:
Global attributes
DOM interface:
interface HTMLTableRowElement : HTMLElement {
  readonly attribute long rowIndex;
  readonly attribute long sectionRowIndex;
  readonly attribute HTMLCollection cells;
  HTMLElement insertCell(optional in long index);
  void deleteCell(in long index);
};

The tr element represents a row of cells in a table.

tr . rowIndex

Returns the position of the row in the table's rows list.

Returns −1 if the element isn't in a table.

tr . sectionRowIndex

Returns the position of the row in the table section's rows list.

Returns −1 if the element isn't in a table section.

tr . cells

Returns an HTMLCollection of the td and th elements of the row.

cell = tr . insertCell( [ index ] )

Creates a td element, inserts it into the table row at the position given by the argument, and returns the td.

The position is relative to the cells in the row. The index −1, which is the default if the argument is omitted, is equivalent to inserting at the end of the row.

If the given position is less than −1 or greater than the number of cells, throws an INDEX_SIZE_ERR exception.

tr . deleteCell(index)

Removes the td or th element with the given position in the row.

The position is relative to the cells in the row. The index −1 is equivalent to deleting the last cell of the row.

If the given position is less than −1 or greater than the index of the last cell, or if there are no cells, throws an INDEX_SIZE_ERR exception.

4.9.10 The td element

Status: Implemented and widely deployed

Categories
Sectioning root.
Contexts in which this element may be used:
As a child of a tr element.
Content model:
Flow content.
Content attributes:
Global attributes
colspan
rowspan
headers
DOM interface:
interface HTMLTableDataCellElement : HTMLTableCellElement {};

The td element represents a data cell in a table.

4.9.11 The th element

Status: Implemented and widely deployed

Categories
None.
Contexts in which this element may be used:
As a child of a tr element.
Content model:
Phrasing content.
Content attributes:
Global attributes
colspan
rowspan
headers
scope
DOM interface:
interface HTMLTableHeaderCellElement : HTMLTableCellElement {
           attribute DOMString scope;
};

The th element represents a header cell in a table.

The th element may have a scope content attribute specified. The scope attribute is an enumerated attribute with five states, four of which have explicit keywords:

The row keyword, which maps to the row state
The row state means the header cell applies to some of the subsequent cells in the same row(s).
The col keyword, which maps to the column state
The column state means the header cell applies to some of the subsequent cells in the same column(s).
The rowgroup keyword, which maps to the row group state
The row group state means the header cell applies to all the remaining cells in the row group. A th element's scope attribute must not be in the row group state if the element is not anchored in a row group.
The colgroup keyword, which maps to the column group state
The column group state means the header cell applies to all the remaining cells in the column group. A th element's scope attribute must not be in the column group state if the element is not anchored in a column group.
The auto state
The auto state makes the header cell apply to a set of cells selected based on context.

The scope attribute's missing value default is the auto state.

The following example shows how the scope attribute's rowgroup value affects which data cells a header cell applies to.

Here is a markup fragment showing a table:

<table>
 <thead>
  <tr> <th> ID <th> Measurement <th> Average <th> Maximum
 <tbody>
  <tr> <td> <th scope=rowgroup> Cats <td> <td>
  <tr> <td> 93 <td> Legs <td> 3.5 <td> 4
  <tr> <td> 10 <td> Tails <td> 1 <td> 1
 <tbody>
  <tr> <td> <th scope=rowgroup> English speakers <td> <td>
  <tr> <td> 32 <td> Legs <td> 2.67 <td> 4
  <tr> <td> 35 <td> Tails <td> 0.33 <td> 1
</table>

This would result in the following table:

ID Measurement Average Maximum
Cats
93 Legs 3.5 4
10 Tails 1 1
English speakers
32 Legs 2.67 4
35 Tails 0.33 1

The headers in the first row all apply directly down to the rows in their column.

The headers with the explicit scope attributes apply to all the cells in their row group other than the cells in the first column.

The remaining headers apply just to the cells to the right of them.

4.9.12 Attributes common to td and th elements

The td and th elements may have a colspan content attribute specified, whose value must be a valid non-negative integer greater than zero.

The td and th elements may also have a rowspan content attribute specified, whose value must be a valid non-negative integer.

These attributes give the number of columns and rows respectively that the cell is to span. These attributes must not be used to overlap cells, as described in the description of the


The td and th element may have a headers content attribute specified. The headers attribute, if specified, must contain a string consisting of an unordered set of unique space-separated tokens, each of which must have the value of an ID of a th element taking part in the same table as the td or th element.

A th element with ID id is said to be directly targeted by all td and th elements in the same table that have headers attributes whose values include as one of their tokens the ID id. A th element A is said to be targeted by a th or td element B if either A is directly targeted by B or if there exists an element C that is itself targeted by the element B and A is directly targeted by C.

A th element must not be targeted by itself.


The td and th elements implement interfaces that inherit from the HTMLTableCellElement interface:

interface HTMLTableCellElement : HTMLElement {
           attribute unsigned long colSpan;
           attribute unsigned long rowSpan;
           attribute DOMString headers;
  readonly attribute long cellIndex;
};
cell . cellIndex

Returns the position of the cell in the row's cells list.

Returns 0 if the element isn't in a row.

4.10 Forms

Status: Working draft

Forms allow unscripted client-server interaction: given a form, a user can provide data, submit it to the server, and have the server act on it accordingly (e.g. returning the results of a search or calculation). The elements used in forms can also be used for user interaction with no associated submission mechanism, in conjunction with scripts.

Mostly for historical reasons, elements in this section fall into several overlapping (but subtly different) categories in addition to the usual ones like flow content, phrasing content, and interactive content.

A number of the elements are form-associated elements, which means they can have a form owner and, to expose this, have a form content attribute with a matching form DOM attribute.

The form-associated elements fall into several subcategories:

Listed

Denotes elements that are listed in the form.elements and fieldset.elements APIs.

Labelable

Denotes elements that can be associated with label elements.

Submittable elements

Denotes elements that can be used for constructing the form data set when a form element is submitted.

Resettable elements

Denotes elements that can be affected when a form element is reset.

In addition, some submittable elements can be, depending on their attributes, buttons. The prose below defines when an element is a button. Some buttons are specifically submit buttons.

The object element is also a form-associated element and can, with the use of a suitable plugin, partake in form submission.

4.10.1 The form element

Status: Working draft

Categories
Flow content.
Contexts in which this element may be used:
Where flow content is expected.
Content model:
Flow content, but with no form element descendants.
Content attributes:
Global attributes
accept-charset
action
autocomplete
enctype
method
name
novalidate
target
DOM interface:
[OverrideBuiltins]
interface HTMLFormElement : HTMLElement {
           attribute DOMString acceptCharset;
           attribute DOMString action;
           attribute boolean autocomplete;
           attribute DOMString enctype;
           attribute DOMString method;
           attribute DOMString name;
           attribute boolean novalidate;
           attribute DOMString target;

  readonly attribute HTMLFormControlsCollection elements;
  readonly attribute long length;
  caller getter any item(in unsigned long index);
  caller getter any namedItem(in DOMString name);

  void submit();
  void reset();
  boolean checkValidity();

  void dispatchFormInput();
  void dispatchFormChange();
};

The form element represents a collection of form-associated elements, some of which can represent editable values that can be submitted to a server for processing.

The accept-charset attribute gives the character encodings that are to be used for the submission. If specified, the value must be an ordered set of unique space-separated tokens, and each token must be the preferred name of an ASCII-compatible character encoding. [IANACHARSET]

The name attribute represents the form's name within the forms collection. The value must not be the empty string, and the value must be unique amongst the form elements in the forms collection that it is in, if any.

The autocomplete attribute is an enumerated attribute. The attribute has two states. The on keyword maps to the on state, and the off keyword maps to the off state. The attribute may also be omitted. The missing value default is the on state. The off state indicates that by default, input elements in the form will have their resulting autocompletion state set to off; the on state indicates that by default, input elements in the form will have their resulting autocompletion state set to on.

The action, enctype, method, novalidate, and target attributes are attributes for form submission.

form . elements

Returns an HTMLCollection of the form controls in the form (excluding image buttons for historical reasons).

form . length

Returns the number of form controls in the form (excluding image buttons for historical reasons).

element = form . item(index)
form[index]
form(index)

Returns the indexth element in the form (excluding image buttons for historical reasons).

element = form . namedItem(name)
form[name]
form(name)

Returns the form control in the form with the given ID or name (excluding image buttons for historical reasons).

Once an element has been referenced using a particular name, that name will continue being available as a way to reference that element in this method, even if the element's actual ID or name changes, for as long as the element remains in the Document.

If there are multiple matching items, then a NodeList object containing all those elements is returned.

Returns null if no element with that ID or name could be found.

form . submit()

Submits the form.

form . reset()

Resets the form.

form . checkValidity()

Returns true if the form's controls are all valid; otherwise, returns false.

form . dispatchFormInput()

Dispatches a forminput event at all the form controls.

form . dispatchFormChange()

Dispatches a formchange event at all the form controls.

4.10.2 The fieldset element

Status: Working draft

Categories
Flow content.
Listed form-associated element.
Contexts in which this element may be used:
Where flow content is expected.
Content model:
One legend element followed by flow content.
Content attributes:
Global attributes
disabled
form
name
DOM interface:
interface HTMLFieldSetElement : HTMLElement {
           attribute boolean disabled;
  readonly attribute HTMLFormElement form;
           attribute DOMString name;

  readonly attribute DOMString type;

  readonly attribute HTMLFormControlsCollection elements;

  readonly attribute boolean willValidate;
  readonly attribute ValidityState validity;
  readonly attribute DOMString validationMessage;
  boolean checkValidity();
  void setCustomValidity(in DOMString error);
};

The fieldset element represents a set of form controls grouped under a common name.

The name of the group is given by the first legend element that is a child of the fieldset element. The remainder of the descendants form the group.

The disabled attribute, when specified, causes all the form control descendants of the fieldset element to be disabled.

The form attribute is used to explicitly associate the fieldset element with its form owner. The name attribute represents the element's name.

fieldset . type

Returns the string "fieldset".

fieldset . elements

Returns an HTMLCollection of the form controls in the element.

4.10.3 The label element

Status: Implemented and widely deployed

Categories
Flow content.
Phrasing content.
Interactive content.
Form-associated element.
Contexts in which this element may be used:
Where phrasing content is expected.
Content model:
Phrasing content, but with no descendant labelable form-associated elements unless it is the element's labeled control, and no descendant label elements.
Content attributes:
Global attributes
form
for
DOM interface:
interface HTMLLabelElement : HTMLElement {
  readonly attribute HTMLFormElement form;
           attribute DOMString htmlFor;
  readonly attribute HTMLElement control;
};

The label represents a caption in a user interface. The caption can be associated with a specific form control, either using for attribute, or by putting the form control inside the label element itself.

The for attribute may be specified to indicate a form control with which the caption is to be associated. If the attribute is specified, the attribute's value must be the ID of a labelable form-associated element in the same Document as the label element.

label . control

Returns the form control that is associated with this element.


control . labels

Returns a NodeList of all the label elements that the form control is associated with.

The following example shows three form controls each with a label, two of which have small text showing the right format for users to use.

<p><label>Full name: <input name=fn> <small>Format: First Last</small></label></p>
<p><label>Age: <input name=age type=number min=0></label></p>
<p><label>Post code: <input name=pc> <small>Format: AB12 3CD</small></label></p>

4.10.4 The input element

Status: Working draft

Categories
Flow content.
Phrasing content.
If the type attribute is not in the Hidden state: Interactive content.
Listed, labelable, submittable, and resettable form-associated element.
Contexts in which this element may be used:
Where phrasing content is expected.
Content model:
Empty.
Content attributes:
Global attributes
accept
alt
autocomplete
autofocus
checked
disabled
form
formaction
formenctype
formmethod
formnovalidate
formtarget
height
list
max
maxlength
min
multiple
name
pattern
placeholder
readonly
required
size
src
step
type
value
width
DOM interface:
interface HTMLInputElement : HTMLElement {
           attribute DOMString accept;
           attribute DOMString alt;
           attribute boolean autocomplete;
           attribute boolean autofocus;
           attribute boolean defaultChecked;
           attribute boolean checked;
           attribute boolean disabled;
  readonly attribute HTMLFormElement form;
  readonly attribute FileList files;
           attribute DOMString formAction;
           attribute DOMString formEnctype;
           attribute DOMString formMethod;
           attribute boolean formNoValidate;
           attribute DOMString formTarget;
           attribute DOMString height;
           attribute boolean indeterminate;
  readonly attribute HTMLElement list;
           attribute DOMString max;
           attribute unsigned long maxLength;
           attribute DOMString min;
           attribute boolean multiple;
           attribute DOMString name;
           attribute DOMString pattern;
           attribute DOMString placeholder;
           attribute boolean readOnly;
           attribute boolean required;
           attribute unsigned long size;
           attribute DOMString src;
           attribute DOMString step;
           attribute DOMString type;
           attribute DOMString defaultValue;
           attribute DOMString value;
           attribute Date valueAsDate;
           attribute float valueAsNumber;
  readonly attribute HTMLOptionElement selectedOption;
           attribute DOMString width;

  void stepUp(in long n);
  void stepDown(in long n);

  readonly attribute boolean willValidate;
  readonly attribute ValidityState validity;
  readonly attribute DOMString validationMessage;
  boolean checkValidity();
  void setCustomValidity(in DOMString error);

  readonly attribute NodeList labels;

  void select();
           attribute unsigned long selectionStart;
           attribute unsigned long selectionEnd;
  void setSelectionRange(in unsigned long start, in unsigned long end);
};

The input element represents a typed data field, usually with a form control to allow the user to edit the data.

The type attribute controls the data type (and associated control) of the element. It is an enumerated attribute. The following table lists the keywords and states for the attribute — the keywords in the left column map to the states in the cell in the second column on the same row as the keyword.

Keyword State Data type Control type
hidden Hidden An arbitrary string n/a
text Text Text with no line breaks Text field
search Search Text with no line breaks Search field
tel Telephone Text with no line breaks A text field
url URL An absolute IRI A text field
email E-mail An e-mail address or list of e-mail addresses A text field
password Password Text with no line breaks (sensitive information) Text field that obscures data entry
datetime Date and Time A date and time (year, month, day, hour, minute, second, fraction of a second) with the time zone set to UTC A date and time control
date Date A date (year, month, day) with no time zone A date control
month Month A date consisting of a year and a month with no time zone A month control
week Week A date consisting of a week-year number and a week number with no time zone A week control
time Time A time (hour, minute, seconds, fractional seconds) with no time zone A time control
datetime-local Local Date and Time A date and time (year, month, day, hour, minute, second, fraction of a second) with no time zone A date and time control
number Number A numerical value A text field or spinner control
range Range A numerical value, with the extra semantic that the exact value is not important A slider control or similar
color Color An sRGB color with 8-bit red, green, and blue components A color well
checkbox Checkbox A set of zero or more values from a predefined list A checkbox
radio Radio Button An enumerated value A radio button
file File Upload Zero or more files each with a MIME type and optionally a file name A label and a button
submit Submit Button An enumerated value, with the extra semantic that it must be the last value selected and initiates form submission A button
image Image Button A coordinate, relative to a particular image's size, with the extra semantic that it must be the last value selected and initiates form submission Either a clickable image, or a button
reset Reset Button n/a A button
button Button n/a A button

The missing value default is the Text state.

Which of the accept, alt, autocomplete, checked, formaction, formenctype, formmethod, formnovalidate, formtarget, height, list, max, maxlength, min, multiple, pattern, readonly, required, size, src, step, and width attributes apply to an input element depends on the state of its type attribute. Similarly, the checked, files, valueAsDate, valueAsNumber, list, and selectedOption DOM attributes, and the stepUp() and stepDown() methods, are specific to certain states. The following table summarises which content attributes, DOM attributes, and methods apply to each state:

Hidden Text, Search, URL, Telephone E-mail Password Date and Time, Date, Month, Week, Time Local Date and Time, Number Range Color Checkbox, Radio Button File Upload Submit Button Image Button Reset Button, Button
accept · · · · · · · · · Yes · · ·
alt · · · · · · · · · · · Yes ·
autocomplete · Yes Yes Yes Yes Yes Yes Yes · · · · ·
checked · · · · · · · · Yes · · · ·
formaction · · · · · · · · · · Yes Yes ·
formenctype · · · · · · · · · · Yes Yes ·
formmethod · · · · · · · · · · Yes Yes ·
formnovalidate · · · · · · · · · · Yes Yes ·
formtarget · · · · · · · · · · Yes Yes ·
height · · · · · · · · · · · Yes ·
list · Yes Yes · Yes Yes Yes Yes · · · · ·
max · · · · Yes Yes Yes · · · · · ·
maxlength · Yes Yes Yes · · · · · · · · ·
min · · · · Yes Yes Yes · · · · · ·
multiple · · Yes · · · · · · Yes · · ·
pattern · Yes Yes Yes · · · · · · · · ·
placeholder · Yes Yes Yes · · · · · · · · ·
readonly · Yes Yes Yes Yes Yes · · · · · · ·
required · Yes Yes Yes Yes Yes · · Yes Yes · · ·
size · Yes Yes Yes · · · · · · · · ·
src · · · · · · · · · · · Yes ·
step · · · · Yes Yes Yes · · · · · ·
width · · · · · · · · · · · Yes ·
checked · · · · · · · · Yes · · · ·
files · · · · · · · · · Yes · · ·
valueAsDate · · · · Yes · · · · · · · ·
valueAsNumber · · · · Yes Yes Yes · · · · · ·
list · Yes Yes · Yes Yes Yes Yes · · · · ·
selectedOption · Yes Yes · Yes Yes Yes Yes · · · · ·
select() · Yes Yes Yes · · · · · · · · ·
selectionStart · Yes Yes Yes · · · · · · · · ·
selectionEnd · Yes Yes Yes · · · · · · · · ·
setSelectionRange() · Yes Yes Yes · · · · · · · · ·
stepDown() · · · · Yes Yes Yes · · · · · ·
stepUp() · · · · Yes Yes Yes · · · · · ·
input event · Yes Yes Yes Yes Yes Yes Yes · · · · ·
change event · Yes Yes Yes Yes Yes Yes Yes Yes Yes · · ·

The value content attribute gives the default value of the input element.

The checked content attribute is a boolean attribute that gives the default checkedness of the input element.

The form attribute is used to explicitly associate the input element with its form owner. The name attribute represents the element's name. The disabled attribute is used to make the control non-interactive and to prevent its value from being submitted. The autofocus attribute controls focus.

4.10.4.1 States of the type attribute
4.10.4.1.1 Hidden state

Status: Last call for comments

The input element represents a value that is not intended to be examined or manipulated by the user.

If the name attribute is present and has a value that is a case-sensitive match for the string "_charset_", then the element's value attribute must be omitted.

4.10.4.1.2 Text state and Search state

Status: Last call for comments

The input element represents a one line plain text edit control for the element's value.

The value attribute, if specified, must have a value that contains no U+000A LINE FEED (LF) or U+000D CARRIAGE RETURN (CR) characters.

4.10.4.1.3 Telephone state

The input element represents a control for editing a telephone number given in the element's value.

The value attribute, if specified, must have a value that contains no U+000A LINE FEED (LF) or U+000D CARRIAGE RETURN (CR) characters.

Unlike the URL and E-mail types, the Telephone type does not enforce a particular syntax. This is intentional; in practice, telephone number fields tend to be free-form fields, because there are a wide variety of valid phone numbers. Systems that need to enforce a particular format are encouraged to use the setCustomValidity() method to hook into the client-side validation mechanism.

4.10.4.1.4 URL state

Status: Last call for comments

The input element represents a control for editing a single absolute URL given in the element's value.

The value attribute, if specified, must have a value that is a valid absolute URL.

4.10.4.1.5 E-mail state

Status: Last call for comments

The input element represents a control for editing a list of e-mail addresses given in the element's value.

If the multiple attribute is specified on the element, then the value attribute, if specified, must have a value that is a valid e-mail address list; otherwise, the value attribute, if specified, must have a value that is a single valid e-mail address.

A valid e-mail address list is a set of comma-separated tokens, where each token is itself a valid e-mail address.

A valid e-mail address is a string that matches the production dot-atom-text "@" dot-atom-text where dot-atom-text is defined in RFC 5322 section 3.2.3. [RFC5322]

4.10.4.1.6 Password state

Status: Last call for comments

The input element represents a one line plain text edit control for the element's value. The user agent should obscure the value so that people other than the user cannot see it.

The value attribute, if specified, must have a value that contains no U+000A LINE FEED (LF) or U+000D CARRIAGE RETURN (CR) characters.

4.10.4.1.7 Date and Time state

Status: Last call for comments

The input element represents a control for setting the element's value to a string representing a specific global date and time.

The value attribute, if specified, must have a value that is a valid global date and time string.

The min attribute, if specified, must have a value that is a valid global date and time string. The max attribute, if specified, must have a value that is a valid global date and time string.

The step attribute is expressed in seconds. The default step is 60 seconds.

4.10.4.1.8 Date state

Status: Last call for comments

The input element represents a control for setting the element's value to a string representing a specific date.

The value attribute, if specified, must have a value that is a valid date string.

The min attribute, if specified, must have a value that is a valid date string. The max attribute, if specified, must have a value that is a valid date string.

The step attribute is expressed in days. The default step is 1 day.

4.10.4.1.9 Month state

Status: Last call for comments

The input element represents a control for setting the element's value to a string representing a specific month.

The value attribute, if specified, must have a value that is a valid month string.

The min attribute, if specified, must have a value that is a valid month string. The max attribute, if specified, must have a value that is a valid month string.

The step attribute is expressed in months. The default step is 1 month.

4.10.4.1.10 Week state

Status: Last call for comments

The input element represents a control for setting the element's value to a string representing a specific week.

The value attribute, if specified, must have a value that is a valid week string.

The min attribute, if specified, must have a value that is a valid week string. The max attribute, if specified, must have a value that is a valid week string.

The step attribute is expressed in weeks. The default step is 1 week.

4.10.4.1.11 Time state

Status: Last call for comments

The input element represents a control for setting the element's value to a string representing a specific time.

The value attribute, if specified, must have a value that is a valid time string.

The min attribute, if specified, must have a value that is a valid time string. The max attribute, if specified, must have a value that is a valid time string.

The step attribute is expressed in seconds. The default step is 60 seconds.

4.10.4.1.12 Local Date and Time state

Status: Last call for comments

The input element represents a control for setting the element's value to a string representing a local date and time, with no time zone information.

The value attribute, if specified, must have a value that is a valid local date and time string.

The min attribute, if specified, must have a value that is a valid local date and time string. The max attribute, if specified, must have a value that is a valid local date and time string.

The step attribute is expressed in seconds. The default step is 60 seconds.

4.10.4.1.13 Number state

Status: Last call for comments

The input element represents a control for setting the element's value to a string representing a number.

The value attribute, if specified, must have a value that is a valid floating point number.

The min attribute, if specified, must have a value that is a valid floating point number. The max attribute, if specified, must have a value that is a valid floating point number.

The default step is 1 (allowing only integers, unless the min attribute has a non-integer value).

4.10.4.1.14 Range state

Status: Last call for comments

The input element represents a control for setting the element's value to a string representing a number, but with the caveat that the exact value is not important, letting UAs provide a simpler interface than they do for the Number state.

The value attribute, if specified, must have a value that is a valid floating point number.

The min attribute, if specified, must have a value that is a valid floating point number. The default minimum is 0. The max attribute, if specified, must have a value that is a valid floating point number. The default maximum is 100.

The default value is the minimum plus half the difference between the minimum and the maximum, unless the maximum is less than the minimum, in which case the default value is the minimum.

The default step is 1 (allowing only integers, unless the min attribute has a non-integer value).

4.10.4.1.15 Color state

Status: Working draft

The input element represents a color well control, for setting the element's value to a string representing a simple color.

The value attribute, if specified, must have a value that is a valid simple color.

4.10.4.1.16 Checkbox state

Status: Last call for comments

The input element represents a two-state control that represents the element's checkedness state. If the element's checkedness state is true, the control represents a positive selection, and if it is false, a negative selection. If the element's indeterminate DOM attribute is set to true, then the control's selection should be obscured as if the control was in a third, indeterminate, state.

The control is never a true tri-state control, even if the element's indeterminate DOM attribute is set to true. The indeterminate DOM attribute only gives the appearance of a third state.

input . indeterminate [ = value ]

When set, overrides the rendering of checkbox controls so that the current value is not visible.

4.10.4.1.17 Radio Button state

Status: Last call for comments

The input element represents a control that, when used in conjunction with other input elements, forms a radio button group in which only one control can have its checkedness state set to true. If the element's checkedness state is true, the control represents the selected control in the group, and if it is false, it indicates a control in the group that is not selected.

The radio button group that contains an input element a also contains all the other input elements b that fulfill all of the following conditions:

A document must not contain an input element whose radio button group contains only that element.

If none of the radio buttons in a radio button group are checked when they are inserted into the document, then they will all be initially unchecked in the interface, until such time as one of them is checked (either by the user or by script).

4.10.4.1.18 File Upload state

Status: Last call for comments

The input element represents a list of selected files, each file consisting of a file name, a file type, and a file body (the contents of the file).


The accept attribute may be specified to provide user agents with a hint of what file types the server will be able to accept.

If specified, the attribute must consist of a set of comma-separated tokens, each of which must be an ASCII case-insensitive match for one of the following:

The string audio/*
Indicates that sound files are accepted.
The string video/*
Indicates that video files are accepted.
The string image/*
Indicates that image files are accepted.
A valid MIME type, with no parameters
Indicates that files of the specified type are accepted.

The tokens must not be ASCII case-insensitive matches for any of the other tokens (i.e. duplicates are not allowed).


4.10.4.1.19 Submit Button state

Status: Last call for comments

The input element represents a button that, when activated, submits the form. The element is a button, specifically a submit button.

The formaction, formenctype, formmethod, formnovalidate, and formtarget attributes are attributes for form submission.

The formnovalidate attribute can be used to make submit buttons that do not trigger the constraint validation.

4.10.4.1.20 Image Button state

Status: Last call for comments

The input element represents either an image from which a user can select a coordinate and submit the form, or alternatively a button from which the user can submit the form. The element is a button, specifically a submit button.


The image is given by the src attribute. The src attribute must be present, and must contain a valid URL referencing a non-interactive, optionally animated, image resource that is neither paged nor scripted.

The alt attribute provides the textual label for the alternative button for users and user agents who cannot use the image. The alt attribute must also be present, and must contain a non-empty string.

The input element supports dimension attributes.

The formaction, formenctype, formmethod, formnovalidate, and formtarget attributes are attributes for form submission.

Many aspects of this state's behavior are similar to the behavior of the img element. Readers are encouraged to read that section, where many of the same requirements are described in more detail.

4.10.4.1.21 Reset Button state

Status: Last call for comments

The input element represents a button that, when activated, resets the form. The element is a button.

4.10.4.1.22 Button state

Status: Last call for comments

The input element represents a button with no default behavior. The element is a button.

4.10.4.2 Common input element attributes
4.10.4.2.1 The autocomplete attribute

Status: Last call for comments

The autocomplete attribute is an enumerated attribute. The attribute has three states. The on keyword maps to the on state, and the off keyword maps to the off state. The attribute may also be omitted. The missing value default is the default state.

The off state indicates that the control's input data is either particularly sensitive (for example the activation code for a nuclear weapon) or is a value that will never be reused (for example a one-time-key for a bank login) and the user will therefore have to explicitly enter the data each time, instead of being able to rely on the UA to prefill the value for him.

Conversely, the on state indicates that the value is not particularly sensitive and the user can expect to be able to rely on his user agent to remember values he has entered for that control.

The default state indicates that the user agent is to use the autocomplete attribute on the element's form owner instead.

Banks frequently do not want UAs to prefill login information:

<p>Account: <input type="text" name="ac" autocomplete="off"></p>
<p>PIN: <input type="text" name="pin" autocomplete="off"></p>
4.10.4.2.2 The list attribute

Status: Last call for comments

The list attribute is used to identify an element that lists predefined options suggested to the user.

If present, its value must be the ID of a datalist element in the same document.

4.10.4.2.3 The readonly attribute

Status: Last call for comments

The readonly attribute is a boolean attribute that controls whether or not the use can edit the form control.

4.10.4.2.4 The size attribute

Status: Last call for comments

The size attribute gives the number of characters that, in a visual rendering, the user agent is to allow the user to see while editing the element's value.

The size attribute, if specified, must have a value that is a valid non-negative integer greater than zero.

4.10.4.2.5 The required attribute

Status: Last call for comments

The required attribute is a boolean attribute. When specified, the element is required.

4.10.4.2.6 The multiple attribute

Status: Last call for comments

The multiple attribute is a boolean attribute that indicates whether the user is to be allowed to specify more than one value.

4.10.4.2.7 The maxlength attribute

Status: Last call for comments

The maxlength attribute is a form control maxlength attribute.

If the input element has a maximum allowed value length, then the code-point length of the value of the element's value attribute must be equal to or less than the element's maximum allowed value length.

4.10.4.2.8 The pattern attribute

Status: Last call for comments

The pattern attribute specifies a regular expression against which the control's value is to be checked.

If specified, the attribute's value must match the JavaScript Pattern production. [ECMA262]

When an input element has a pattern attribute specified, authors should include a title attribute to give a description of the pattern. User agents may use the contents of this attribute, if it is present, when informing the user that the pattern is not matched, or at any other suitable time, such as in a tooltip or read out by assistive technology when the control gains focus.

For example, the following snippet:

<label> Part number:
 <input pattern="[0-9][A-Z]{3}" name="part"
        title="A part number is a digit followed by three uppercase letters."/>
</label>

...could cause the UA to display an alert such as:

A part number is a digit followed by three uppercase letters.
You cannot complete this form until the field is correct.

When a control has a pattern attribute, the title attribute, if used, must describe the pattern. Additional information could also be included, so long as it assists the user in filling in the control. Otherwise, assistive technology would be impaired.

For instance, if the title attribute contained the caption of the control, assistive technology could end up saying something like The text you have entered does not match the required pattern. Birthday, which is not useful.

4.10.4.2.9 The min and max attributes

Status: Last call for comments

The min and max attributes indicate the allowed range of values for the element.

4.10.4.2.10 The step attribute

Status: Last call for comments

The step attribute indicates the granularity that is expected (and required) of the value, by limiting the allowed values.

The step attribute, if specified, must either have a value that is a valid floating point number that parses to a number that is greater than zero, or must have a value that is an ASCII case-insensitive match for the string "any".

4.10.4.2.11 The placeholder attribute

Status: Last call for comments

The placeholder attribute represents a short hint (a word or short phrase) intended to aid the user with data entry. A hint could be a sample value or a brief description of the expected format. The attribute, if specified, must have a value that contains no U+000A LINE FEED (LF) or U+000D CARRIAGE RETURN (CR) characters.

For a longer hint or other advisory text, the title attribute is more appropriate.

The placeholder attribute should not be used as an alternative to a label.

Here is an example of a mail configuration user interface that uses the placeholder attribute:

<fieldset>
 <legend>Mail Account</legend>
 <p><label>Name: <input type="text" name="fullname" placeholder="John Ratzenberger"></label></p>
 <p><label>Address: <input type="email" name="address" placeholder="john@example.net"></label></p>
 <p><label>Password: <input type="password" name="password"></label></p>
 <p><label>Description: <input type="text" name="desc" placeholder="My Email Account"></label></p>
</fieldset>
4.10.4.3 Common input element APIs

Status: Last call for comments

input . value [ = value ]

Returns the current value of the form control.

Can be set, to change the value.

Throws an INVALID_ACCESS_ERR exception if it is set when the control is a file upload control.

input . checked [ = value ]

Returns the current checkedness of the form control.

Can be set, to change the checkedness.

input . files

Returns a FileList object listing the selected files of the form control.

input . valueAsDate [ = value ]

Returns a Date object representing the form control's value, if applicable; otherwise, returns null.

Can be set, to change the value.

Throws an INVALID_ACCESS_ERR exception if the control isn't date- or time-based.

input . valueAsNumber [ = value ]

Returns a number representing the form control's value, if applicable; otherwise, returns null.

Can be set, to change the value.

Throws an INVALID_ACCESS_ERR exception if the control is neither date- or time-based nor numeric.

input . stepUp(n)
input . stepDown(n)

Changes the form control's value by the value given in the step attribute, multiplied by n.

Throws INVALID_ACCESS_ERR exception if the control is neither date- or time-based nor numeric, if the step attribute's value is "any", if the current value could not be parsed, or if stepping in the given direction by the given amount would take the value out of range.

input . list

Returns the datalist element indicated by the list attribute.

input . selectedOption

Returns the option element from the datalist element indicated by the list attribute that matches the form control's value.

4.10.5 The button element

Status: Last call for comments

Categories
Flow content.
Phrasing content.
Interactive content.
Listed, labelable, and submittable form-associated element.
Contexts in which this element may be used:
Where phrasing content is expected.
Content model:
Phrasing content, but there must be no interactive content descendant.
Content attributes:
Global attributes
autofocus
disabled
form
formaction
formenctype
formmethod
formnovalidate
formtarget
name
type
value
DOM interface:
interface HTMLButtonElement : HTMLElement {
           attribute boolean autofocus;
           attribute boolean disabled;
  readonly attribute HTMLFormElement form;
           attribute DOMString formaction;
           attribute DOMString formenctype;
           attribute DOMString formmethod;
           attribute DOMString formnoValidate;
           attribute DOMString formtarget;
           attribute DOMString name;
           attribute DOMString type;
           attribute DOMString value;

  readonly attribute boolean willValidate;
  readonly attribute ValidityState validity;
  readonly attribute DOMString validationMessage;
  boolean checkValidity();
  void setCustomValidity(in DOMString error);

  readonly attribute NodeList labels;
};

The button element represents a button.

The element is a button.

The type attribute controls the behavior of the button when it is activated. It is an enumerated attribute. The following table lists the keywords and states for the attribute — the keywords in the left column map to the states in the cell in the second column on the same row as the keyword.

Keyword State Brief description
submit Submit Button Submits the form.
reset Reset Button Resets the form.
button Button Does nothing.

The missing value default is the Submit Button state.

If the type attribute is in the Submit Button state, the element is specifically a submit button.

The form attribute is used to explicitly associate the button element with its form owner. The name attribute represents the element's name. The disabled attribute is used to make the control non-interactive and to prevent its value from being submitted. The autofocus attribute controls focus. The formaction, formenctype, formmethod, formnovalidate, and formtarget attributes are attributes for form submission.

The formnovalidate attribute can be used to make submit buttons that do not trigger the constraint validation.

The value attribute gives the element's value for the purposes of form submission. The value attribute must not be present unless the form attribute is present. The element's value is the value of the element's value attribute, if there is one, or the empty string otherwise.

A button (and its value) is only included in the form submission if the button itself was used to initiate the form submission.

4.10.6 The select element

Status: Last call for comments

Categories
Flow content.
Phrasing content.
Interactive content.
Listed, labelable, submittable, and resettable form-associated element.
Contexts in which this element may be used:
Where phrasing content is expected.
Content model:
Zero or more option or optgroup elements.
Content attributes:
Global attributes
autofocus
disabled
form
multiple
name
size
DOM interface:
interface HTMLSelectElement : HTMLElement {
           attribute boolean autofocus;
           attribute boolean disabled;
  readonly attribute HTMLFormElement form;
           attribute boolean multiple;
           attribute DOMString name;
           attribute unsigned long size;

  readonly attribute DOMString type;

  readonly attribute HTMLOptionsCollection options;
           attribute unsigned long length;
  caller getter any item(in unsigned long index);
  caller getter any namedItem(in DOMString name);
  void add(in HTMLElement element, optional in HTMLElement before);
  void add(in HTMLElement element, in long before);
  void remove(in long index);

  readonly attribute HTMLCollection selectedOptions;
           attribute long selectedIndex;
           attribute DOMString value;

  readonly attribute boolean willValidate;
  readonly attribute ValidityState validity;
  readonly attribute DOMString validationMessage;
  boolean checkValidity();
  void setCustomValidity(in DOMString error);

  readonly attribute NodeList labels;
};

The select element represents a control for selecting amongst a set of options.

The multiple attribute is a boolean attribute. If the attribute is present, then the select element represents a control for selecting zero or more options from the list of options. If the attribute is absent, then the select element represents a control for selecting a single option from the list of options.

The list of options for a select element consists of all the option element children of the select element, and all the option element children of all the optgroup element children of the select element, in tree order.

The size attribute gives the number of options to show to the user. The size attribute, if specified, must have a value that is a valid non-negative integer greater than zero. If the multiple attribute is present, then the size attribute's default value is 4. If the multiple attribute is absent, then the size attribute's default value is 1.

The form attribute is used to explicitly associate the select element with its form owner. The name attribute represents the element's name. The disabled attribute is used to make the control non-interactive and to prevent its value from being submitted. The autofocus attribute controls focus.

select . type

Returns "select-multiple" if the element has a multiple attribute, and "select-one" otherwise.

select . options

Returns an HTMLOptionsCollection of the list of options.

select . length [ = value ]

Returns the number of elements in the list of options.

When set to a smaller number, truncates the number of option elements in the select.

When set to a greater number, adds new blank option elements to the select.

element = select . item(index)
select[index]
select(index)

Returns the item with index index from the list of options. The items are sorted in tree order.

Returns null if index is out of range.

element = select . namedItem(name)
select[name]
select(name)

Returns the item with ID or name name from the list of options.

If there are multiple matching items, then a NodeList object containing all those elements is returned.

Returns null if no element with that ID could be found.

select . add(element [, before ])

Inserts element before the node given by before.

The before argument can be a number, in which case element is inserted before the item with that number, or an element from the list of options, in which case element is inserted before that element.

If before is omitted, null, or a number out of range, then element will be added at the end of the list.

This method will throw a HIERARCHY_REQUEST_ERR exception if element is an ancestor of the element into which it is to be inserted. If element is not an option or optgroup element, then the method does nothing.

select . selectedOptions

Returns an HTMLCollection of the list of options that are selected.

select . selectedIndex [ = value ]

Returns the index of the first selected item, if any, or −1 if there is no selected item.

Can be set, to change the selection.

select . value [ = value ]

Returns the value of the first selected item, if any, or the empty string if there is no selected item.

Can be set, to change the selection.

4.10.7 The datalist element

Status: Last call for comments

Categories
Flow content.
Phrasing content.
Contexts in which this element may be used:
Where phrasing content is expected.
Content model:
Either: phrasing content.
Or: Zero or more option elements.
Content attributes:
Global attributes
DOM interface:
interface HTMLDataListElement : HTMLElement {
  readonly attribute HTMLCollection options;
};

The datalist element represents a set of option elements that represent predefined options for other controls. The contents of the element represents fallback content for legacy user agents, intermixed with option elements that represent the predefined options. In the rendering, the datalist element represents nothing.

The datalist element is hooked up to an input element using the list attribute on the input element.

Each option element that is a descendant of the datalist element, that is not disabled, and whose value is a string that isn't the empty string, represents a suggestion. Each suggestion has a value and a label.

datalist . options

Returns an HTMLCollection of the options elements of the table.

4.10.8 The optgroup element

Status: Last call for comments

Categories
None.
Contexts in which this element may be used:
As a child of a select element.
Content model:
Zero or more option elements.
Content attributes:
Global attributes
disabled
label
DOM interface:
interface HTMLOptGroupElement : HTMLElement {
           attribute boolean disabled;
           attribute DOMString label;
};

The optgroup element represents a group of option elements with a common label.

The element's group of option elements consists of the option elements that are children of the optgroup element.

The disabled attribute is a boolean attribute and can be used to disable a group of option elements together.

The label attribute must be specified. Its value gives the name of the group, for the purposes of the user interface.

4.10.9 The option element

Status: Last call for comments

Categories
None.
Contexts in which this element may be used:
As a child of a select element.
As a child of a datalist element.
As a child of an optgroup element.
Content model:
Text.
Content attributes:
Global attributes
disabled
label
selected
value
DOM interface:
[NamedConstructor=Option(),
 NamedConstructor=Option(in DOMString text),
 NamedConstructor=Option(in DOMString text, in DOMString value),
 NamedConstructor=Option(in DOMString text, in DOMString value, in boolean defaultSelected),
 NamedConstructor=Option(in DOMString text, in DOMString value, in boolean defaultSelected, in boolean selected)]
interface HTMLOptionElement : HTMLElement {
           attribute boolean disabled;
  readonly attribute HTMLFormElement form;
           attribute DOMString label;
           attribute boolean defaultSelected;
           attribute boolean selected;
           attribute DOMString value;

           attribute DOMString text;
  readonly attribute long index;
};

The option element represents an option in a select element or as part of a list of suggestions in a datalist element.

The disabled attribute is a boolean attribute. An option element is disabled if its disabled attribute is present or if it is a child of an optgroup element whose disabled attribute is present.

The label attribute provides a label for element. The label of an option element is the value of the label attribute, if there is one, or the textContent of the element, if there isn't.

The value attribute provides a value for element. The value of an option element is the value of the value attribute, if there is one, or the textContent of the element, if there isn't.

The selected attribute represents the default selectedness of the element.

option . selected

Returns true if the element is selected, and false otherwise.

option . index

Returns the index of the element in its select element's options list.

option . form

Returns the element's form element, if any, or null otherwise.

option = new Option( [ text [, value [, defaultSelected [, selected ] ] ] ] )

Returns a new option element.

The text argument sets the contents of the element.

The value argument sets the value attribute.

The defaultSelected argument sets the selected attribute.

The selected argument sets whether or not the element is selected. If it is omitted, even if the defaultSelected argument is true, the element is not selected.

4.10.10 The textarea element

Status: Last call for comments

Categories
Flow content.
Phrasing content.
Interactive content.
Listed, labelable, submittable, and resettable form-associated element.
Contexts in which this element may be used:
Where phrasing content is expected.
Content model:
Text.
Content attributes:
Global attributes
autofocus
cols
disabled
form
maxlength
name
placeholder
readonly
required
rows
wrap
DOM interface:
interface HTMLTextAreaElement : HTMLElement {
           attribute boolean autofocus;
           attribute unsigned long cols;
           attribute boolean disabled;
  readonly attribute HTMLFormElement form;
           attribute unsigned long maxLength;
           attribute DOMString name;
           attribute DOMString placeholder;
           attribute boolean readOnly;
           attribute boolean required;
           attribute unsigned long rows;
           attribute DOMString wrap;

  readonly attribute DOMString type;
           attribute DOMString defaultValue;
           attribute DOMString value;
  readonly attribute unsigned long textLength;

  readonly attribute boolean willValidate;
  readonly attribute ValidityState validity;
  readonly attribute DOMString validationMessage;
  boolean checkValidity();
  void setCustomValidity(in DOMString error);

  readonly attribute NodeList labels;

  void select();
           attribute unsigned long selectionStart;
           attribute unsigned long selectionEnd;
  void setSelectionRange(in unsigned long start, in unsigned long end);
};

The textarea element represents a multiline plain text edit control. The contents of the control represent the control's default value.

The readonly attribute is a boolean attribute used to control whether the text can be edited by the user or not.

The cols attribute specifies the expected maximum number of characters per line. If the cols attribute is specified, its value must be a valid non-negative integer greater than zero.

The rows attribute specifies the number of lines to show. If the rows attribute is specified, its value must be a valid non-negative integer greater than zero.

The wrap attribute is an enumerated attribute with two keywords and states: the soft keyword which maps to the Soft state, and the hard keyword which maps to the Hard state. The missing value default is the Soft state.

If the element's wrap attribute is in the Hard state, the cols attribute must be specified.

The required attribute is a boolean attribute. When specified, the user will be required to enter a value before submitting the form.

The placeholder attribute represents a hint (a word or short phrase) intended to aid the user with data entry. A hint could be a sample value or a brief description of the expected format. The attribute, if specified, must have a value that contains no U+000A LINE FEED (LF) or U+000D CARRIAGE RETURN (CR) characters.

For a longer hint or other advisory text, the title attribute is more appropriate.

The placeholder attribute should not be used as an alternative to a label.

The form attribute is used to explicitly associate the textarea element with its form owner. The name attribute represents the element's name. The disabled attribute is used to make the control non-interactive and to prevent its value from being submitted. The autofocus attribute controls focus.

textarea . type

Returns the string "textarea".

textarea . value

Returns the current value of the element.

Can be set, to change the value.

4.10.11 The keygen element

Status: First draft

Categories
Flow content.
Phrasing content.
Interactive content.
Listed, labelable, submittable, and resettable form-associated element.
Contexts in which this element may be used:
Where phrasing content is expected.
Content model:
Empty.
Content attributes:
Global attributes
autofocus
challenge
disabled
form
keytype
name
DOM interface:
interface HTMLKeygenElement : HTMLElement {
           attribute boolean autofocus;
           attribute DOMString challenge;
           attribute boolean disabled;
  readonly attribute HTMLFormElement form;
           attribute DOMString keytype;
           attribute DOMString name;

  readonly attribute DOMString type;

  readonly attribute boolean willValidate;
  readonly attribute ValidityState validity;
  readonly attribute DOMString validationMessage;
  boolean checkValidity();
  void setCustomValidity(in DOMString error);

  readonly attribute NodeList labels;
};

The keygen element represents a key pair generator control. When the control's form is submitted, the private key is stored in the local keystore, and the public key is packaged and sent to the server.

The challenge attribute may be specified. Its value will be packaged with the submitted key.

The keytype attribute is an enumerated attribute. The following table lists the keywords and states for the attribute — the keywords in the left column map to the states listed in the cell in the second column on the same row as the keyword.

Keyword State
rsa RSA

The invalid value default state is the unknown state. The missing value default state is the RSA state.

The form attribute is used to explicitly associate the keygen element with its form owner. The name attribute represents the element's name. The disabled attribute is used to make the control non-interactive and to prevent its value from being submitted. The autofocus attribute controls focus.

keygen . type

Returns the string "keygen".

This specification does not specify how the private key generated is to be used. It is expected that after receiving the SignedPublicKeyAndChallenge (SPKAC) structure, the server will generate a client certificate and offer it back to the user for download; this certificate, once downloaded and stored in the key store along with the private key, can then be used to authenticate to services that use SSL and certificate authentication.

4.10.12 The output element

Status: Last call for comments

Categories
Flow content.
Phrasing content.
Listed and resettable form-associated element.
Contexts in which this element may be used:
Where phrasing content is expected.
Content model:
Phrasing content.
Content attributes:
Global attributes
for
form
name
DOM interface:
interface HTMLOutputElement : HTMLElement {
           attribute DOMString htmlFor;
  readonly attribute HTMLFormElement form;
           attribute DOMString name;

  readonly attribute DOMString type;
           attribute DOMString defaultValue;
           attribute DOMString value;

  readonly attribute boolean willValidate;
  readonly attribute ValidityState validity;
  readonly attribute DOMString validationMessage;
  boolean checkValidity();
  void setCustomValidity(in DOMString error);
};

The output element represents the result of a calculation.

The for content attribute allows an explicit relationship to be made between the result of a calculation and the elements that represent the values that went into the calculation or that otherwise influenced the calculation. The for attribute, if specified, must contain a string consisting of an unordered set of unique space-separated tokens, each of which must have the value of an ID of an element in the same Document.

The form attribute is used to explicitly associate the output element with its form owner. The name attribute represents the element's name.

output . value [ = value ]

Returns the element's current value.

Can be set, to change the value.

output . defaultValue [ = value ]

Returns the element's current default value.

Can be set, to change the default value.

output . type

Returns the string "output".

4.10.13 Association of controls and forms

Status: Last call for comments

A form-associated element can have a relationship with a form element, which is called the element's form owner. If a form-associated element is not associated with a form element, its form owner is said to be null.

A form-associated element is, by default, associated with its nearest ancestor form element, but may have a form attribute specified to override this.

If a form-associated element has a form attribute specified, then its value must be the ID of a form element in the element's owner Document.

element . form

Returns the element's form owner.

Returns null if there isn't one.

4.10.14 Attributes common to form controls

4.10.14.1 Naming form controls

Status: Last call for comments

The name content attribute gives the name of the form control, as used in form submission and in the form element's elements object. If the attribute is specified, its value must not be the empty string.

4.10.14.2 Enabling and disabling form controls

Status: Last call for comments

The disabled content attribute is a boolean attribute.

A form control is disabled if its disabled attribute is set, or if it is a descendant of a fieldset element whose disabled attribute is set.

4.10.14.3 Autofocusing a form control

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The autofocus content attribute allows the user to indicate that a control is to be focused as soon as the page is loaded, allowing the user to just start typing without having to manually focus the main control.

The autofocus attribute is a boolean attribute.

There must not be more than one element in the document with the autofocus attribute specified.

In the following snippet, the text control would be focused when the document was loaded.

<input maxlength="256" name="q" value="" autofocus>
<input type="submit" value="Search">
4.10.14.4 Limiting user input length

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A form control maxlength attribute, controlled by a dirty value flag declares a limit on the number of characters a user can input.

If an element has its form control maxlength attribute specified, the attribute's value must be a valid non-negative integer. If the attribute is specified and applying the rules for parsing non-negative integers to its value results in a number, then that number is the element's maximum allowed value length. If the attribute is omitted or parsing its value results in an error, then there is no maximum allowed value length.

4.10.14.5 Form submission

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Attributes for form submission can be specified both on form elements and on submit button (elements that represent buttons that submit forms, e.g. an input element whose type attribute is in the Submit Button state).

The attributes for form submission that may be specified on form elements are action, enctype, method, novalidate, and target.

The corresponding attributes for form submission that may be specified on submit button are formaction, formenctype, formmethod, formnovalidate, and formtarget. When omitted, they default to the values given on the corresponding attributes on the form element.


The action and formaction content attributes, if specified, must have a value that is a valid URL.

The action of an element is the value of the element's formaction attribute, if the element is a submit button and has such an attribute, or the value of its form owner's action attribute, if it has one, or else the empty string.


The method and formmethod content attributes are enumerated attributes with the following keywords and states:

The missing value default for these attributes is the GET state.

The method of an element is one of those four states. If the element is a submit button and has a formmethod attribute, then the element's method is that attribute's state; otherwise, it is the form owner's method attribute's state.


The enctype and formenctype content attributes are enumerated attributes with the following keywords and states:

The missing value default for these attributes is the application/x-www-form-urlencoded state.

The enctype of an element is one of those three states. If the element is a submit button and has a formenctype attribute, then the element's enctype is that attribute's state; otherwise, it is the form owner's enctype attribute's state.


The target and formtarget content attributes, if specified, must have values that are valid browsing context names or keywords.

The target of an element is the value of the element's formtarget attribute, if the element is a submit button and has such an attribute; or the value of its form owner's target attribute, if it has such an attribute; or, if one of the child nodes of the head element is a base element with a target attribute, then the value of the target attribute of the first such base element; or, if there is no such element, the empty string.


The novalidate and formnovalidate content attributes are boolean attributes. If present, they indicate that the form is not to be validated during submission.

The no-validate state of an element is true if the element is a submit button and the element's formnovalidate attribute is present, or if the element's form owner's novalidate attribute is present, and false otherwise.

This attribute is useful to include "save" buttons on forms that have validation constraints, to allow users to save their progress even though they haven't fully entered the data in the form. The following example shows a simple form that has two required fields. There are three buttons: one to submit the form, which requires both fields to be filled in; one to save the form so that the user can come back and fill it in later; and one to cancel the form altogether.

<form action="editor.cgi" method="post">
 <p><label>Name: <input required name=fn></label></p>
 <p><label>Essay: <textarea name=essay></textarea></label></p>
 <p><input type=submit name=submit value="Submit essay"></p>
 <p><input type=submit formnovalidate name=save value="Save essay"></p>
 <p><input type=submit formnovalidate name=cancel value="Cancel"></p>
</form>

4.10.15 Constraints

4.10.15.1 Definitions
4.10.15.2 The constraint validation API

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element . willValidate

Returns true if the element will be validated when the form is submitted; false otherwise.

element . setCustomValidity(message)

Sets a custom error, so that the element would fail to validate. The given message is the message to be shown to the user when reporting the problem to the user.

If the argument is the empty string, clears the custom error.

element . validity . valueMissing

Returns true if the element has no value but is a required field; false otherwise.

element . validity . typeMismatch

Returns true if the element's value is not in the correct syntax; false otherwise.

element . validity . patternMismatch

Returns true if the element's value doesn't match the provided pattern; false otherwise.

element . validity . tooLong

Returns true if the element's value is longer than the provided maximum length; false otherwise.

element . validity . rangeUnderflow

Returns true if the element's value is lower than the provided minimum; false otherwise.

element . validity . rangeOverflow

Returns true if the element's value is higher than the provided maximum; false otherwise.

element . validity . stepMismatch

Returns true if the element's value doesn't fit the rules given by the step attribute; false otherwise.

element . validity . customError

Returns true if the element has a custom error; false otherwise.

element . validity . valid

Returns true if the element's value has no validity problems; false otherwise.

valid = element . checkValidity()

Returns true if the element's value has no validity problems; false otherwise. Fires an invalid event at the element in the latter case.

element . validationMessage

Returns the error message that would be shown to the user if the element was to be checked for validity.

In the following example, a script checks the value of a form control each time it is edited, and whenever it is not a valid value, uses the setCustomValidity() method to set an appropriate message.

<label>Feeling: <input name=f type="text" oninput="check(this)"></label>
<script>
 function check(input) {
   if (input.value == "good" ||
       input.value == "fine" ||
       input.value == "tired") {
     input.setCustomValidity('"' + input.value + '" is not a feeling.');
   } else {
     // input is fine -- reset the error message
     input.setCustomValidity('');
   }
 }
</script>

4.10.16 Form submission

...

4.11 Interactive elements

4.11.1 The details element

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Categories
Flow content.
Interactive content.
Contexts in which this element may be used:
Where flow content is expected.
Content model:
One legend element followed by flow content.
Content attributes:
Global attributes
open
DOM interface:
interface HTMLDetailsElement : HTMLElement {
           attribute boolean open;
};

The details element represents additional information or controls which the user can obtain on demand.

The details element is not appropriate for footnotes. Please see the section on footnotes for details on how to mark up footnotes.

The first element child of a details element, a legend element, represents the summary of the details.

The open content attribute is a boolean attribute. If present, it indicates that the details are to be shown to the user. If the attribute is absent, the details are not to be shown.