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<!DOCTYPE html><html lang=en-US-x-hixie><title>HTML Standard</title><script>
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   <hgroup><h1 class=allcaps>HTML</h1>
    <h2 class="no-num no-toc">Living Standard &mdash; Last Updated 11 November 2013</h2>
   </hgroup><dl><dt><strong>Web developer edition:</strong></dt>
    <dd><strong><a href=http://developers.whatwg.org/>http://developers.whatwg.org/</a></strong></dd>
    <dt>Multiple-page version:</dt>
    <dd><a href=http://www.whatwg.org/specs/web-apps/current-work/multipage/>http://whatwg.org/html</a></dd>
    <dt>One-page version:</dt>
    <dd><a href=http://www.whatwg.org/specs/web-apps/current-work/>http://whatwg.org/c</a></dd>
    <dt>Validators</dt>
    <dd><a href=http://validator.whatwg.org/>http://validator.whatwg.org/</a></dd>
    <dt>Participate:</dt>
    <dd><a href=http://www.whatwg.org/mailing-list>whatwg@whatwg.org</a></dd>
    <dd><a href=http://forums.whatwg.org/>http://forums.whatwg.org/</a></dd>
    <dd><a href=http://wiki.whatwg.org/wiki/IRC>IRC: #whatwg on Freenode</a></dd>
    <dt>FAQ:</dt>
    <dd><a href=http://wiki.whatwg.org/wiki/FAQ>http://wiki.whatwg.org/wiki/FAQ</a></dd>
    <dt>Version history:</dt>
    <dd>Twitter updates: <a href=http://twitter.com/WHATWG>http://twitter.com/WHATWG</a></dd>
    <dd>Commit-Watchers mailing list: <a href=http://lists.whatwg.org/listinfo.cgi/commit-watchers-whatwg.org>http://lists.whatwg.org/listinfo.cgi/commit-watchers-whatwg.org</a></dd>
    <dd>Interactive Web interface: <a href=http://html5.org/tools/web-apps-tracker>http://html5.org/tools/web-apps-tracker</a></dd>
    <dd>Subversion interface: <a href=http://svn.whatwg.org/>http://svn.whatwg.org/</a></dd>
    <dt>Issues:</dt>
    <dd>To view the open bugs: <a href="https://www.w3.org/Bugs/Public/buglist.cgi?query_format=advanced&amp;short_desc_type=allwordssubstr&amp;short_desc=&amp;product=WHATWG&amp;component=HTML&amp;longdesc_type=allwordssubstr&amp;longdesc=&amp;bug_file_loc_type=allwordssubstr&amp;bug_file_loc=&amp;status_whiteboard_type=allwordssubstr&amp;status_whiteboard=&amp;keywords_type=allwords&amp;keywords=&amp;bug_status=UNCONFIRMED&amp;bug_status=NEW&amp;bug_status=ASSIGNED&amp;bug_status=REOPENED&amp;emailtype1=substring&amp;email1=&amp;emailtype2=substring&amp;email2=&amp;bug_id_type=anyexact&amp;bug_id=&amp;votes=&amp;chfieldfrom=&amp;chfieldto=Now&amp;chfieldvalue=&amp;cmdtype=doit&amp;order=Reuse+same+sort+as+last+time&amp;field0-0-0=noop&amp;type0-0-0=noop&amp;value0-0-0=">HTML bug list</a></dd>
    <dd>To file bugs, use the "submit review comments" feature at the bottom of the window</dd>
    <dd>To send feedback by e-mail: <a href=http://www.whatwg.org/mailing-list>whatwg@whatwg.org</a></dd>
    <dd>To view and vote on e-mail feedback: <a href=http://www.whatwg.org/issues/>http://www.whatwg.org/issues/</a></dd>
    <dt>Editor:</dt>
    <dd>Ian Hickson, Google, ian@hixie.ch</dd>
   </dl><p class=copyright>&copy; Copyright 2004-2011 Apple Computer, Inc.,
   Mozilla Foundation, and Opera Software ASA.</p>
   <p class=copyright>You are granted a license to use, reproduce
   and create derivative works of this document.</p>
  </header><hr><h2 class="no-num no-toc" id=contents>Table of contents</h2>
  
<!--begin-toc-->
<ol class=toc>
 <li><a href=#introduction><span class=secno>1 </span>Introduction</a>
  <ol>
   <li><a href=#abstract><span class=secno>1.1 </span>Where does this specification fit?</a></li>
   <li><a href=#is-this-html5?><span class=secno>1.2 </span>Is this HTML5?</a></li>
   <li><a href=#background><span class=secno>1.3 </span>Background</a></li>
   <li><a href=#audience><span class=secno>1.4 </span>Audience</a></li>
   <li><a href=#scope><span class=secno>1.5 </span>Scope</a></li>
   <li><a href=#history-1><span class=secno>1.6 </span>History</a></li>
   <li><a href=#design-notes><span class=secno>1.7 </span>Design notes</a>
    <ol>
     <li><a href=#serializability-of-script-execution><span class=secno>1.7.1 </span>Serializability of script execution</a></li>
     <li><a href=#compliance-with-other-specifications><span class=secno>1.7.2 </span>Compliance with other specifications</a></li>
     <li><a href=#extensibility><span class=secno>1.7.3 </span>Extensibility</a></ol></li>
   <li><a href=#html-vs-xhtml><span class=secno>1.8 </span>HTML vs XHTML</a></li>
   <li><a href=#structure-of-this-specification><span class=secno>1.9 </span>Structure of this specification</a>
    <ol>
     <li><a href=#how-to-read-this-specification><span class=secno>1.9.1 </span>How to read this specification</a></li>
     <li><a href=#typographic-conventions><span class=secno>1.9.2 </span>Typographic conventions</a></ol></li>
   <li><a href=#fingerprint><span class=secno>1.10 </span>Privacy concerns</a></li>
   <li><a href=#a-quick-introduction-to-html><span class=secno>1.11 </span>A quick introduction to HTML</a>
    <ol>
     <li><a href=#writing-secure-applications-with-html><span class=secno>1.11.1 </span>Writing secure applications with HTML</a></li>
     <li><a href=#common-pitfalls-to-avoid-when-using-the-scripting-apis><span class=secno>1.11.2 </span>Common pitfalls to avoid when using the scripting APIs</a></ol></li>
   <li><a href=#conformance-requirements-for-authors><span class=secno>1.12 </span>Conformance requirements for authors</a>
    <ol>
     <li><a href=#presentational-markup><span class=secno>1.12.1 </span>Presentational markup</a></li>
     <li><a href=#syntax-errors><span class=secno>1.12.2 </span>Syntax errors</a></li>
     <li><a href=#restrictions-on-content-models-and-on-attribute-values><span class=secno>1.12.3 </span>Restrictions on content models and on attribute values</a></ol></li>
   <li><a href=#suggested-reading><span class=secno>1.13 </span>Suggested reading</a></ol></li>
 <li><a href=#infrastructure><span class=secno>2 </span>Common infrastructure</a>
  <ol>
   <li><a href=#terminology><span class=secno>2.1 </span>Terminology</a>
    <ol>
     <li><a href=#resources><span class=secno>2.1.1 </span>Resources</a></li>
     <li><a href=#xml><span class=secno>2.1.2 </span>XML</a></li>
     <li><a href=#dom-trees><span class=secno>2.1.3 </span>DOM trees</a></li>
     <li><a href=#scripting-0><span class=secno>2.1.4 </span>Scripting</a></li>
     <li><a href=#plugins><span class=secno>2.1.5 </span>Plugins</a></li>
     <li><a href=#encoding-terminology><span class=secno>2.1.6 </span>Character encodings</a></ol></li>
   <li><a href=#conformance-requirements><span class=secno>2.2 </span>Conformance requirements</a>
    <ol>
     <li><a href=#conformance-classes><span class=secno>2.2.1 </span>Conformance classes</a></li>
     <li><a href=#dependencies><span class=secno>2.2.2 </span>Dependencies</a></li>
     <li><a href=#extensibility-0><span class=secno>2.2.3 </span>Extensibility</a></li>
     <li><a href=#interactions-with-xpath-and-xslt><span class=secno>2.2.4 </span>Interactions with XPath and XSLT</a></ol></li>
   <li><a href=#case-sensitivity-and-string-comparison><span class=secno>2.3 </span>Case-sensitivity and string comparison</a></li>
   <li><a href=#common-microsyntaxes><span class=secno>2.4 </span>Common microsyntaxes</a>
    <ol>
     <li><a href=#common-parser-idioms><span class=secno>2.4.1 </span>Common parser idioms</a></li>
     <li><a href=#boolean-attributes><span class=secno>2.4.2 </span>Boolean attributes</a></li>
     <li><a href=#keywords-and-enumerated-attributes><span class=secno>2.4.3 </span>Keywords and enumerated attributes</a></li>
     <li><a href=#numbers><span class=secno>2.4.4 </span>Numbers</a>
      <ol>
       <li><a href=#signed-integers><span class=secno>2.4.4.1 </span>Signed integers</a></li>
       <li><a href=#non-negative-integers><span class=secno>2.4.4.2 </span>Non-negative integers</a></li>
       <li><a href=#floating-point-numbers><span class=secno>2.4.4.3 </span>Floating-point numbers</a></li>
       <li><a href=#percentages-and-dimensions><span class=secno>2.4.4.4 </span>Percentages and lengths</a></li>
       <li><a href=#lists-of-integers><span class=secno>2.4.4.5 </span>Lists of integers</a></li>
       <li><a href=#lists-of-dimensions><span class=secno>2.4.4.6 </span>Lists of dimensions</a></ol></li>
     <li><a href=#dates-and-times><span class=secno>2.4.5 </span>Dates and times</a>
      <ol>
       <li><a href=#months><span class=secno>2.4.5.1 </span>Months</a></li>
       <li><a href=#dates><span class=secno>2.4.5.2 </span>Dates</a></li>
       <li><a href=#yearless-dates><span class=secno>2.4.5.3 </span>Yearless dates</a></li>
       <li><a href=#times><span class=secno>2.4.5.4 </span>Times</a></li>
       <li><a href=#local-dates-and-times><span class=secno>2.4.5.5 </span>Local dates and times</a></li>
       <li><a href=#time-zones><span class=secno>2.4.5.6 </span>Time zones</a></li>
       <li><a href=#global-dates-and-times><span class=secno>2.4.5.7 </span>Global dates and times</a></li>
       <li><a href=#weeks><span class=secno>2.4.5.8 </span>Weeks</a></li>
       <li><a href=#durations><span class=secno>2.4.5.9 </span>Durations</a></li>
       <li><a href=#vaguer-moments-in-time><span class=secno>2.4.5.10 </span>Vaguer moments in time</a></ol></li>
     <li><a href=#colors><span class=secno>2.4.6 </span>Colors</a></li>
     <li><a href=#space-separated-tokens><span class=secno>2.4.7 </span>Space-separated tokens</a></li>
     <li><a href=#comma-separated-tokens><span class=secno>2.4.8 </span>Comma-separated tokens</a></li>
     <li><a href=#syntax-references><span class=secno>2.4.9 </span>References</a></li>
     <li><a href=#mq><span class=secno>2.4.10 </span>Media queries</a></ol></li>
   <li><a href=#urls><span class=secno>2.5 </span>URLs</a>
    <ol>
     <li><a href=#terminology-0><span class=secno>2.5.1 </span>Terminology</a></li>
     <li><a href=#resolving-urls><span class=secno>2.5.2 </span>Resolving URLs</a></li>
     <li><a href=#dynamic-changes-to-base-urls><span class=secno>2.5.3 </span>Dynamic changes to base URLs</a></ol></li>
   <li><a href=#fetching-resources><span class=secno>2.6 </span>Fetching resources</a>
    <ol>
     <li><a href=#terminology-1><span class=secno>2.6.1 </span>Terminology</a></li>
     <li><a href=#processing-model><span class=secno>2.6.2 </span>Processing model</a></li>
     <li><a href=#encrypted-http-and-related-security-concerns><span class=secno>2.6.3 </span>Encrypted HTTP and related security concerns</a></li>
     <li><a href=#content-type-sniffing><span class=secno>2.6.4 </span>Determining the type of a resource</a></li>
     <li><a href=#extracting-character-encodings-from-meta-elements><span class=secno>2.6.5 </span>Extracting character encodings from <code>meta</code> elements</a></li>
     <li><a href=#cors-settings-attributes><span class=secno>2.6.6 </span>CORS settings attributes</a></li>
     <li><a href=#cors-enabled-fetch><span class=secno>2.6.7 </span>CORS-enabled fetch</a></ol></li>
   <li><a href=#common-dom-interfaces><span class=secno>2.7 </span>Common DOM interfaces</a>
    <ol>
     <li><a href=#reflecting-content-attributes-in-idl-attributes><span class=secno>2.7.1 </span>Reflecting content attributes in IDL attributes</a></li>
     <li><a href=#collections-0><span class=secno>2.7.2 </span>Collections</a>
      <ol>
       <li><a href=#htmlallcollection-0><span class=secno>2.7.2.1 </span>HTMLAllCollection</a></li>
       <li><a href=#htmlformcontrolscollection-0><span class=secno>2.7.2.2 </span>HTMLFormControlsCollection</a></li>
       <li><a href=#htmloptionscollection-0><span class=secno>2.7.2.3 </span>HTMLOptionsCollection</a></li>
       <li><a href=#htmlpropertiescollection-0><span class=secno>2.7.2.4 </span>HTMLPropertiesCollection</a></ol></li>
     <li><a href=#domstringmap-0><span class=secno>2.7.3 </span>DOMStringMap</a></li>
     <li><a href=#domelementmap-0><span class=secno>2.7.4 </span>DOMElementMap</a></li>
     <li><a href=#transferable-objects><span class=secno>2.7.5 </span>Transferable objects</a></li>
     <li><a href=#safe-passing-of-structured-data><span class=secno>2.7.6 </span>Safe passing of structured data</a></li>
     <li><a href=#callbacks><span class=secno>2.7.7 </span>Callbacks</a></li>
     <li><a href=#garbage-collection><span class=secno>2.7.8 </span>Garbage collection</a></ol></li>
   <li><a href=#namespaces><span class=secno>2.8 </span>Namespaces</a></ol></li>
 <li><a href=#dom><span class=secno>3 </span>Semantics, structure, and APIs of HTML documents</a>
  <ol>
   <li><a href=#documents><span class=secno>3.1 </span>Documents</a>
    <ol>
     <li><a href=#the-document-object><span class=secno>3.1.1 </span>The <code>Document</code> object</a></li>
     <li><a href=#security-document><span class=secno>3.1.2 </span>Security</a></li>
     <li><a href=#resource-metadata-management><span class=secno>3.1.3 </span>Resource metadata management</a></li>
     <li><a href=#dom-tree-accessors><span class=secno>3.1.4 </span>DOM tree accessors</a></li>
     <li><a href=#loading-xml-documents><span class=secno>3.1.5 </span>Loading XML documents</a></ol></li>
   <li><a href=#elements><span class=secno>3.2 </span>Elements</a>
    <ol>
     <li><a href=#semantics-0><span class=secno>3.2.1 </span>Semantics</a></li>
     <li><a href=#elements-in-the-dom><span class=secno>3.2.2 </span>Elements in the DOM</a></li>
     <li><a href=#element-definitions><span class=secno>3.2.3 </span>Element definitions</a>
      <ol>
       <li><a href=#attributes><span class=secno>3.2.3.1 </span>Attributes</a></ol></li>
     <li><a href=#content-models><span class=secno>3.2.4 </span>Content models</a>
      <ol>
       <li><a href=#kinds-of-content><span class=secno>3.2.4.1 </span>Kinds of content</a>
        <ol>
         <li><a href=#metadata-content-0><span class=secno>3.2.4.1.1 </span>Metadata content</a></li>
         <li><a href=#flow-content-0><span class=secno>3.2.4.1.2 </span>Flow content</a></li>
         <li><a href=#sectioning-content-0><span class=secno>3.2.4.1.3 </span>Sectioning content</a></li>
         <li><a href=#heading-content-0><span class=secno>3.2.4.1.4 </span>Heading content</a></li>
         <li><a href=#phrasing-content-0><span class=secno>3.2.4.1.5 </span>Phrasing content</a></li>
         <li><a href=#embedded-content-0><span class=secno>3.2.4.1.6 </span>Embedded content</a></li>
         <li><a href=#interactive-content-0><span class=secno>3.2.4.1.7 </span>Interactive content</a></li>
         <li><a href=#palpable-content-0><span class=secno>3.2.4.1.8 </span>Palpable content</a></li>
         <li><a href=#script-supporting-elements-0><span class=secno>3.2.4.1.9 </span>Script-supporting elements</a></ol></li>
       <li><a href=#transparent-content-models><span class=secno>3.2.4.2 </span>Transparent content models</a></li>
       <li><a href=#paragraphs><span class=secno>3.2.4.3 </span>Paragraphs</a></ol></li>
     <li><a href=#global-attributes><span class=secno>3.2.5 </span>Global attributes</a>
      <ol>
       <li><a href=#the-id-attribute><span class=secno>3.2.5.1 </span>The <code>id</code> attribute</a></li>
       <li><a href=#the-title-attribute><span class=secno>3.2.5.2 </span>The <code title=attr-title>title</code> attribute</a></li>
       <li><a href=#the-lang-and-xml:lang-attributes><span class=secno>3.2.5.3 </span>The <code title=attr-lang>lang</code> and <code title=attr-xml-lang>xml:lang</code> attributes</a></li>
       <li><a href=#the-translate-attribute><span class=secno>3.2.5.4 </span>The <code title=attr-translate>translate</code> attribute</a></li>
       <li><a href=#the-xml:base-attribute-(xml-only)><span class=secno>3.2.5.5 </span>The <code>xml:base</code> attribute (XML only)</a></li>
       <li><a href=#the-dir-attribute><span class=secno>3.2.5.6 </span>The <code>dir</code> attribute</a></li>
       <li><a href=#classes><span class=secno>3.2.5.7 </span>The <code>class</code> attribute</a></li>
       <li><a href=#the-style-attribute><span class=secno>3.2.5.8 </span>The <code>style</code> attribute</a></li>
       <li><a href=#embedding-custom-non-visible-data-with-the-data-*-attributes><span class=secno>3.2.5.9 </span>Embedding custom non-visible data with the <code title=attr-data-*>data-*</code> attributes</a></ol></li>
     <li><a href=#requirements-relating-to-bidirectional-algorithm-formatting-characters><span class=secno>3.2.6 </span>Requirements relating to bidirectional-algorithm formatting characters</a></li>
     <li><a href=#wai-aria><span class=secno>3.2.7 </span>WAI-ARIA</a></ol></ol></li>
 <li><a href=#semantics><span class=secno>4 </span>The elements of HTML</a>
  <ol>
   <li><a href=#the-root-element><span class=secno>4.1 </span>The root element</a>
    <ol>
     <li><a href=#the-html-element><span class=secno>4.1.1 </span>The <code>html</code> element</a></ol></li>
   <li><a href=#document-metadata><span class=secno>4.2 </span>Document metadata</a>
    <ol>
     <li><a href=#the-head-element><span class=secno>4.2.1 </span>The <code>head</code> element</a></li>
     <li><a href=#the-title-element><span class=secno>4.2.2 </span>The <code>title</code> element</a></li>
     <li><a href=#the-base-element><span class=secno>4.2.3 </span>The <code>base</code> element</a></li>
     <li><a href=#the-link-element><span class=secno>4.2.4 </span>The <code>link</code> element</a></li>
     <li><a href=#the-meta-element><span class=secno>4.2.5 </span>The <code>meta</code> element</a>
      <ol>
       <li><a href=#standard-metadata-names><span class=secno>4.2.5.1 </span>Standard metadata names</a></li>
       <li><a href=#other-metadata-names><span class=secno>4.2.5.2 </span>Other metadata names</a></li>
       <li><a href=#pragma-directives><span class=secno>4.2.5.3 </span>Pragma directives</a></li>
       <li><a href=#other-pragma-directives><span class=secno>4.2.5.4 </span>Other pragma directives</a></li>
       <li><a href=#charset><span class=secno>4.2.5.5 </span>Specifying the document's character encoding</a></ol></li>
     <li><a href=#the-style-element><span class=secno>4.2.6 </span>The <code>style</code> element</a></li>
     <li><a href=#styling><span class=secno>4.2.7 </span>Styling</a></ol></li>
   <li><a href=#sections><span class=secno>4.3 </span>Sections</a>
    <ol>
     <li><a href=#the-body-element><span class=secno>4.3.1 </span>The <code>body</code> element</a></li>
     <li><a href=#the-article-element><span class=secno>4.3.2 </span>The <code>article</code> element</a></li>
     <li><a href=#the-section-element><span class=secno>4.3.3 </span>The <code>section</code> element</a></li>
     <li><a href=#the-nav-element><span class=secno>4.3.4 </span>The <code>nav</code> element</a></li>
     <li><a href=#the-aside-element><span class=secno>4.3.5 </span>The <code>aside</code> element</a></li>
     <li><a href=#the-h1,-h2,-h3,-h4,-h5,-and-h6-elements><span class=secno>4.3.6 </span>The <code>h1</code>, <code>h2</code>, <code>h3</code>, <code>h4</code>, <code>h5</code>, and
  <code>h6</code> elements</a></li>
     <li><a href=#the-hgroup-element><span class=secno>4.3.7 </span>The <code>hgroup</code> element</a></li>
     <li><a href=#the-header-element><span class=secno>4.3.8 </span>The <code>header</code> element</a></li>
     <li><a href=#the-footer-element><span class=secno>4.3.9 </span>The <code>footer</code> element</a></li>
     <li><a href=#the-address-element><span class=secno>4.3.10 </span>The <code>address</code> element</a></li>
     <li><a href=#headings-and-sections><span class=secno>4.3.11 </span>Headings and sections</a>
      <ol>
       <li><a href=#outlines><span class=secno>4.3.11.1 </span>Creating an outline</a></li>
       <li><a href=#sample-outlines><span class=secno>4.3.11.2 </span>Sample outlines</a></ol></li>
     <li><a href=#usage-summary-0><span class=secno>4.3.12 </span>Usage summary</a>
      <ol>
       <li><a href=#article-or-section><span class=secno>4.3.12.1 </span>Article or section?</a></ol></ol></li>
   <li><a href=#grouping-content><span class=secno>4.4 </span>Grouping content</a>
    <ol>
     <li><a href=#the-p-element><span class=secno>4.4.1 </span>The <code>p</code> element</a></li>
     <li><a href=#the-hr-element><span class=secno>4.4.2 </span>The <code>hr</code> element</a></li>
     <li><a href=#the-pre-element><span class=secno>4.4.3 </span>The <code>pre</code> element</a></li>
     <li><a href=#the-blockquote-element><span class=secno>4.4.4 </span>The <code>blockquote</code> element</a></li>
     <li><a href=#the-ol-element><span class=secno>4.4.5 </span>The <code>ol</code> element</a></li>
     <li><a href=#the-ul-element><span class=secno>4.4.6 </span>The <code>ul</code> element</a></li>
     <li><a href=#the-li-element><span class=secno>4.4.7 </span>The <code>li</code> element</a></li>
     <li><a href=#the-dl-element><span class=secno>4.4.8 </span>The <code>dl</code> element</a></li>
     <li><a href=#the-dt-element><span class=secno>4.4.9 </span>The <code>dt</code> element</a></li>
     <li><a href=#the-dd-element><span class=secno>4.4.10 </span>The <code>dd</code> element</a></li>
     <li><a href=#the-figure-element><span class=secno>4.4.11 </span>The <code>figure</code> element</a></li>
     <li><a href=#the-figcaption-element><span class=secno>4.4.12 </span>The <code>figcaption</code> element</a></li>
     <li><a href=#the-main-element><span class=secno>4.4.13 </span>The <code>main</code> element</a></li>
     <li><a href=#the-div-element><span class=secno>4.4.14 </span>The <code>div</code> element</a></ol></li>
   <li><a href=#text-level-semantics><span class=secno>4.5 </span>Text-level semantics</a>
    <ol>
     <li><a href=#the-a-element><span class=secno>4.5.1 </span>The <code>a</code> element</a></li>
     <li><a href=#the-em-element><span class=secno>4.5.2 </span>The <code>em</code> element</a></li>
     <li><a href=#the-strong-element><span class=secno>4.5.3 </span>The <code>strong</code> element</a></li>
     <li><a href=#the-small-element><span class=secno>4.5.4 </span>The <code>small</code> element</a></li>
     <li><a href=#the-s-element><span class=secno>4.5.5 </span>The <code>s</code> element</a></li>
     <li><a href=#the-cite-element><span class=secno>4.5.6 </span>The <code>cite</code> element</a></li>
     <li><a href=#the-q-element><span class=secno>4.5.7 </span>The <code>q</code> element</a></li>
     <li><a href=#the-dfn-element><span class=secno>4.5.8 </span>The <code>dfn</code> element</a></li>
     <li><a href=#the-abbr-element><span class=secno>4.5.9 </span>The <code>abbr</code> element</a></li>
     <li><a href=#the-data-element><span class=secno>4.5.10 </span>The <code>data</code> element</a></li>
     <li><a href=#the-time-element><span class=secno>4.5.11 </span>The <code>time</code> element</a></li>
     <li><a href=#the-code-element><span class=secno>4.5.12 </span>The <code>code</code> element</a></li>
     <li><a href=#the-var-element><span class=secno>4.5.13 </span>The <code>var</code> element</a></li>
     <li><a href=#the-samp-element><span class=secno>4.5.14 </span>The <code>samp</code> element</a></li>
     <li><a href=#the-kbd-element><span class=secno>4.5.15 </span>The <code>kbd</code> element</a></li>
     <li><a href=#the-sub-and-sup-elements><span class=secno>4.5.16 </span>The <code>sub</code> and <code>sup</code> elements</a></li>
     <li><a href=#the-i-element><span class=secno>4.5.17 </span>The <code>i</code> element</a></li>
     <li><a href=#the-b-element><span class=secno>4.5.18 </span>The <code>b</code> element</a></li>
     <li><a href=#the-u-element><span class=secno>4.5.19 </span>The <code>u</code> element</a></li>
     <li><a href=#the-mark-element><span class=secno>4.5.20 </span>The <code>mark</code> element</a></li>
     <li><a href=#the-ruby-element><span class=secno>4.5.21 </span>The <code>ruby</code> element</a></li>
     <li><a href=#the-rt-element><span class=secno>4.5.22 </span>The <code>rt</code> element</a></li>
     <li><a href=#the-rp-element><span class=secno>4.5.23 </span>The <code>rp</code> element</a></li>
     <li><a href=#the-bdi-element><span class=secno>4.5.24 </span>The <code>bdi</code> element</a></li>
     <li><a href=#the-bdo-element><span class=secno>4.5.25 </span>The <code>bdo</code> element</a></li>
     <li><a href=#the-span-element><span class=secno>4.5.26 </span>The <code>span</code> element</a></li>
     <li><a href=#the-br-element><span class=secno>4.5.27 </span>The <code>br</code> element</a></li>
     <li><a href=#the-wbr-element><span class=secno>4.5.28 </span>The <code>wbr</code> element</a></li>
     <li><a href=#usage-summary><span class=secno>4.5.29 </span>Usage summary</a></ol></li>
   <li><a href=#edits><span class=secno>4.6 </span>Edits</a>
    <ol>
     <li><a href=#the-ins-element><span class=secno>4.6.1 </span>The <code>ins</code> element</a></li>
     <li><a href=#the-del-element><span class=secno>4.6.2 </span>The <code>del</code> element</a></li>
     <li><a href=#attributes-common-to-ins-and-del-elements><span class=secno>4.6.3 </span>Attributes common to <code>ins</code> and <code>del</code> elements</a></li>
     <li><a href=#edits-and-paragraphs><span class=secno>4.6.4 </span>Edits and paragraphs</a></li>
     <li><a href=#edits-and-lists><span class=secno>4.6.5 </span>Edits and lists</a></li>
     <li><a href=#edits-and-tables><span class=secno>4.6.6 </span>Edits and tables</a></ol></li>
   <li><a href=#embedded-content-1><span class=secno>4.7 </span>Embedded content</a>
    <ol>
     <li><a href=#the-img-element><span class=secno>4.7.1 </span>The <code>img</code> element</a>
      <ol>
       <li><a href=#alt><span class=secno>4.7.1.1 </span>Requirements for providing text to act as an alternative for images</a>
        <ol>
         <li><a href=#general-guidelines><span class=secno>4.7.1.1.1 </span>General guidelines</a></li>
         <li><a href=#a-link-or-button-containing-nothing-but-the-image><span class=secno>4.7.1.1.2 </span>A link or button containing nothing but the image</a></li>
         <li><a href=#a-phrase-or-paragraph-with-an-alternative-graphical-representation:-charts,-diagrams,-graphs,-maps,-illustrations><span class=secno>4.7.1.1.3 </span>A phrase or paragraph with an alternative graphical representation: charts, diagrams, graphs, maps, illustrations</a></li>
         <li><a href=#a-short-phrase-or-label-with-an-alternative-graphical-representation:-icons,-logos><span class=secno>4.7.1.1.4 </span>A short phrase or label with an alternative graphical representation: icons, logos</a></li>
         <li><a href=#text-that-has-been-rendered-to-a-graphic-for-typographical-effect><span class=secno>4.7.1.1.5 </span>Text that has been rendered to a graphic for typographical effect</a></li>
         <li><a href=#a-graphical-representation-of-some-of-the-surrounding-text><span class=secno>4.7.1.1.6 </span>A graphical representation of some of the surrounding text</a></li>
         <li><a href="#a-purely-decorative-image-that-doesn't-add-any-information"><span class=secno>4.7.1.1.7 </span>A purely decorative image that doesn't add any information</a></li>
         <li><a href=#a-group-of-images-that-form-a-single-larger-picture-with-no-links><span class=secno>4.7.1.1.8 </span>A group of images that form a single larger picture with no links</a></li>
         <li><a href=#a-group-of-images-that-form-a-single-larger-picture-with-links><span class=secno>4.7.1.1.9 </span>A group of images that form a single larger picture with links</a></li>
         <li><a href=#a-key-part-of-the-content><span class=secno>4.7.1.1.10 </span>A key part of the content</a></li>
         <li><a href=#an-image-not-intended-for-the-user><span class=secno>4.7.1.1.11 </span>An image not intended for the user</a></li>
         <li><a href=#an-image-in-an-e-mail-or-private-document-intended-for-a-specific-person-who-is-known-to-be-able-to-view-images><span class=secno>4.7.1.1.12 </span>An image in an e-mail or private document intended for a specific person who is known to be able to view images</a></li>
         <li><a href=#guidance-for-markup-generators><span class=secno>4.7.1.1.13 </span>Guidance for markup generators</a></li>
         <li><a href=#guidance-for-conformance-checkers><span class=secno>4.7.1.1.14 </span>Guidance for conformance checkers</a></ol></li>
       <li><a href=#adaptive-images><span class=secno>4.7.1.2 </span>Adaptive images</a></ol></li>
     <li><a href=#the-iframe-element><span class=secno>4.7.2 </span>The <code>iframe</code> element</a></li>
     <li><a href=#the-embed-element><span class=secno>4.7.3 </span>The <code>embed</code> element</a></li>
     <li><a href=#the-object-element><span class=secno>4.7.4 </span>The <code>object</code> element</a></li>
     <li><a href=#the-param-element><span class=secno>4.7.5 </span>The <code>param</code> element</a></li>
     <li><a href=#the-video-element><span class=secno>4.7.6 </span>The <code>video</code> element</a></li>
     <li><a href=#the-audio-element><span class=secno>4.7.7 </span>The <code>audio</code> element</a></li>
     <li><a href=#the-source-element><span class=secno>4.7.8 </span>The <code>source</code> element</a></li>
     <li><a href=#the-track-element><span class=secno>4.7.9 </span>The <code>track</code> element</a></li>
     <li><a href=#media-elements><span class=secno>4.7.10 </span>Media elements</a>
      <ol>
       <li><a href=#error-codes><span class=secno>4.7.10.1 </span>Error codes</a></li>
       <li><a href=#location-of-the-media-resource><span class=secno>4.7.10.2 </span>Location of the media resource</a></li>
       <li><a href=#mime-types><span class=secno>4.7.10.3 </span>MIME types</a></li>
       <li><a href=#network-states><span class=secno>4.7.10.4 </span>Network states</a></li>
       <li><a href=#loading-the-media-resource><span class=secno>4.7.10.5 </span>Loading the media resource</a></li>
       <li><a href=#offsets-into-the-media-resource><span class=secno>4.7.10.6 </span>Offsets into the media resource</a></li>
       <li><a href=#ready-states><span class=secno>4.7.10.7 </span>Ready states</a></li>
       <li><a href=#playing-the-media-resource><span class=secno>4.7.10.8 </span>Playing the media resource</a></li>
       <li><a href=#seeking><span class=secno>4.7.10.9 </span>Seeking</a></li>
       <li><a href=#media-resources-with-multiple-media-tracks><span class=secno>4.7.10.10 </span>Media resources with multiple media tracks</a>
        <ol>
         <li><a href=#audiotracklist-and-videotracklist-objects><span class=secno>4.7.10.10.1 </span><code>AudioTrackList</code> and <code>VideoTrackList</code> objects</a></li>
         <li><a href=#selecting-specific-audio-and-video-tracks-declaratively><span class=secno>4.7.10.10.2 </span>Selecting specific audio and video tracks declaratively</a></ol></li>
       <li><a href=#synchronising-multiple-media-elements><span class=secno>4.7.10.11 </span>Synchronising multiple media elements</a>
        <ol>
         <li><a href=#introduction-0><span class=secno>4.7.10.11.1 </span>Introduction</a></li>
         <li><a href=#media-controllers><span class=secno>4.7.10.11.2 </span>Media controllers</a></li>
         <li><a href=#assigning-a-media-controller-declaratively><span class=secno>4.7.10.11.3 </span>Assigning a media controller declaratively</a></ol></li>
       <li><a href=#timed-text-tracks><span class=secno>4.7.10.12 </span>Timed text tracks</a>
        <ol>
         <li><a href=#text-track-model><span class=secno>4.7.10.12.1 </span>Text track model</a></li>
         <li><a href=#sourcing-in-band-text-tracks><span class=secno>4.7.10.12.2 </span>Sourcing in-band text tracks</a></li>
         <li><a href=#sourcing-out-of-band-text-tracks><span class=secno>4.7.10.12.3 </span>Sourcing out-of-band text tracks</a></li>
         <li><a href=#guidelines-for-exposing-cues-in-various-formats-as-text-track-cues><span class=secno>4.7.10.12.4 </span>Guidelines for exposing cues in various formats as text track cues</a></li>
         <li><a href=#text-track-api><span class=secno>4.7.10.12.5 </span>Text track API</a></li>
         <li><a href=#text-tracks-describing-chapters><span class=secno>4.7.10.12.6 </span>Text tracks describing chapters</a></li>
         <li><a href=#cue-events><span class=secno>4.7.10.12.7 </span>Event definitions</a></ol></li>
       <li><a href=#user-interface><span class=secno>4.7.10.13 </span>User interface</a></li>
       <li><a href=#time-ranges><span class=secno>4.7.10.14 </span>Time ranges</a></li>
       <li><a href=#event-definitions><span class=secno>4.7.10.15 </span>Event definitions</a></li>
       <li><a href=#mediaevents><span class=secno>4.7.10.16 </span>Event summary</a></li>
       <li><a href=#security-and-privacy-considerations><span class=secno>4.7.10.17 </span>Security and privacy considerations</a></li>
       <li><a href=#best-practices-for-authors-using-media-elements><span class=secno>4.7.10.18 </span>Best practices for authors using media elements</a></li>
       <li><a href=#best-practices-for-implementors-of-media-elements><span class=secno>4.7.10.19 </span>Best practices for implementors of media elements</a></ol></li>
     <li><a href=#the-map-element><span class=secno>4.7.11 </span>The <code>map</code> element</a></li>
     <li><a href=#the-area-element><span class=secno>4.7.12 </span>The <code>area</code> element</a></li>
     <li><a href=#image-maps><span class=secno>4.7.13 </span>Image maps</a>
      <ol>
       <li><a href=#authoring><span class=secno>4.7.13.1 </span>Authoring</a></li>
       <li><a href=#processing-model-0><span class=secno>4.7.13.2 </span>Processing model</a></ol></li>
     <li><a href=#mathml><span class=secno>4.7.14 </span>MathML</a></li>
     <li><a href=#svg-0><span class=secno>4.7.15 </span>SVG</a></li>
     <li><a href=#dimension-attributes><span class=secno>4.7.16 </span>Dimension attributes</a></ol></li>
   <li><a href=#links><span class=secno>4.8 </span>Links</a>
    <ol>
     <li><a href=#introduction-1><span class=secno>4.8.1 </span>Introduction</a></li>
     <li><a href=#links-created-by-a-and-area-elements><span class=secno>4.8.2 </span>Links created by <code>a</code> and <code>area</code> elements</a></li>
     <li><a href=#following-hyperlinks-0><span class=secno>4.8.3 </span>Following hyperlinks</a></li>
     <li><a href=#downloading-resources><span class=secno>4.8.4 </span>Downloading resources</a>
      <ol>
       <li><a href=#hyperlink-auditing><span class=secno>4.8.4.1 </span>Hyperlink auditing</a></ol></li>
     <li><a href=#linkTypes><span class=secno>4.8.5 </span>Link types</a>
      <ol>
       <li><a href=#rel-alternate><span class=secno>4.8.5.1 </span>Link type "<code>alternate</code>"</a></li>
       <li><a href=#link-type-author><span class=secno>4.8.5.2 </span>Link type "<code>author</code>"</a></li>
       <li><a href=#link-type-bookmark><span class=secno>4.8.5.3 </span>Link type "<code>bookmark</code>"</a></li>
       <li><a href=#link-type-external><span class=secno>4.8.5.4 </span>Link type "<code>external</code>"</a></li>
       <li><a href=#link-type-help><span class=secno>4.8.5.5 </span>Link type "<code>help</code>"</a></li>
       <li><a href=#rel-icon><span class=secno>4.8.5.6 </span>Link type "<code>icon</code>"</a></li>
       <li><a href=#link-type-license><span class=secno>4.8.5.7 </span>Link type "<code>license</code>"</a></li>
       <li><a href=#link-type-nofollow><span class=secno>4.8.5.8 </span>Link type "<code>nofollow</code>"</a></li>
       <li><a href=#link-type-noreferrer><span class=secno>4.8.5.9 </span>Link type "<code>noreferrer</code>"</a></li>
       <li><a href=#link-type-pingback><span class=secno>4.8.5.10 </span>Link type "<code>pingback</code>"</a></li>
       <li><a href=#link-type-prefetch><span class=secno>4.8.5.11 </span>Link type "<code>prefetch</code>"</a></li>
       <li><a href=#link-type-search><span class=secno>4.8.5.12 </span>Link type "<code>search</code>"</a></li>
       <li><a href=#link-type-sidebar><span class=secno>4.8.5.13 </span>Link type "<code>sidebar</code>"</a></li>
       <li><a href=#link-type-stylesheet><span class=secno>4.8.5.14 </span>Link type "<code>stylesheet</code>"</a></li>
       <li><a href=#link-type-tag><span class=secno>4.8.5.15 </span>Link type "<code>tag</code>"</a></li>
       <li><a href=#sequential-link-types><span class=secno>4.8.5.16 </span>Sequential link types</a>
        <ol>
         <li><a href=#link-type-next><span class=secno>4.8.5.16.1 </span>Link type "<code>next</code>"</a></li>
         <li><a href=#link-type-prev><span class=secno>4.8.5.16.2 </span>Link type "<code>prev</code>"</a></ol></li>
       <li><a href=#other-link-types><span class=secno>4.8.5.17 </span>Other link types</a></ol></ol></li>
   <li><a href=#tabular-data><span class=secno>4.9 </span>Tabular data</a>
    <ol>
     <li><a href=#the-table-element><span class=secno>4.9.1 </span>The <code>table</code> element</a>
      <ol>
       <li><a href=#table-descriptions-techniques><span class=secno>4.9.1.1 </span>Techniques for describing tables</a></li>
       <li><a href=#table-layout-techniques><span class=secno>4.9.1.2 </span>Techniques for table design</a></ol></li>
     <li><a href=#the-caption-element><span class=secno>4.9.2 </span>The <code>caption</code> element</a></li>
     <li><a href=#the-colgroup-element><span class=secno>4.9.3 </span>The <code>colgroup</code> element</a></li>
     <li><a href=#the-col-element><span class=secno>4.9.4 </span>The <code>col</code> element</a></li>
     <li><a href=#the-tbody-element><span class=secno>4.9.5 </span>The <code>tbody</code> element</a></li>
     <li><a href=#the-thead-element><span class=secno>4.9.6 </span>The <code>thead</code> element</a></li>
     <li><a href=#the-tfoot-element><span class=secno>4.9.7 </span>The <code>tfoot</code> element</a></li>
     <li><a href=#the-tr-element><span class=secno>4.9.8 </span>The <code>tr</code> element</a></li>
     <li><a href=#the-td-element><span class=secno>4.9.9 </span>The <code>td</code> element</a></li>
     <li><a href=#the-th-element><span class=secno>4.9.10 </span>The <code>th</code> element</a></li>
     <li><a href=#attributes-common-to-td-and-th-elements><span class=secno>4.9.11 </span>Attributes common to <code>td</code> and <code>th</code> elements</a></li>
     <li><a href=#processing-model-1><span class=secno>4.9.12 </span>Processing model</a>
      <ol>
       <li><a href=#forming-a-table><span class=secno>4.9.12.1 </span>Forming a table</a></li>
       <li><a href=#header-and-data-cell-semantics><span class=secno>4.9.12.2 </span>Forming relationships between data cells and header cells</a></ol></li>
     <li><a href=#table-sorting-model><span class=secno>4.9.13 </span>Table sorting model</a></li>
     <li><a href=#examples><span class=secno>4.9.14 </span>Examples</a></ol></li>
   <li><a href=#forms><span class=secno>4.10 </span>Forms</a>
    <ol>
     <li><a href=#introduction-2><span class=secno>4.10.1 </span>Introduction</a>
      <ol>
       <li><a href="#writing-a-form's-user-interface"><span class=secno>4.10.1.1 </span>Writing a form's user interface</a></li>
       <li><a href=#implementing-the-server-side-processing-for-a-form><span class=secno>4.10.1.2 </span>Implementing the server-side processing for a form</a></li>
       <li><a href=#configuring-a-form-to-communicate-with-a-server><span class=secno>4.10.1.3 </span>Configuring a form to communicate with a server</a></li>
       <li><a href=#client-side-form-validation><span class=secno>4.10.1.4 </span>Client-side form validation</a></li>
       <li><a href=#enabling-client-side-automatic-filling-of-form-controls><span class=secno>4.10.1.5 </span>Enabling client-side automatic filling of form controls</a></li>
       <li><a href=#improving-the-user-experience-on-mobile-devices><span class=secno>4.10.1.6 </span>Improving the user experience on mobile devices</a></li>
       <li><a href=#the-difference-between-the-field-type,-the-autofill-field-name,-and-the-input-modality><span class=secno>4.10.1.7 </span>The difference between the field type, the autofill field name, and the input modality</a></li>
       <li><a href=#input-author-notes><span class=secno>4.10.1.8 </span>Date, time, and number formats</a></ol></li>
     <li><a href=#categories><span class=secno>4.10.2 </span>Categories</a></li>
     <li><a href=#the-form-element><span class=secno>4.10.3 </span>The <code>form</code> element</a></li>
     <li><a href=#the-label-element><span class=secno>4.10.4 </span>The <code>label</code> element</a></li>
     <li><a href=#the-input-element><span class=secno>4.10.5 </span>The <code>input</code> element</a>
      <ol>
       <li><a href=#states-of-the-type-attribute><span class=secno>4.10.5.1 </span>States of the <code title=attr-input-type>type</code> attribute</a>
        <ol>
         <li><a href="#hidden-state-(type=hidden)"><span class=secno>4.10.5.1.1 </span>Hidden state (<code title="">type=hidden</code>)</a></li>
         <li><a href="#text-(type=text)-state-and-search-state-(type=search)"><span class=secno>4.10.5.1.2 </span>Text (<code title="">type=text</code>) state and Search state (<code title="">type=search</code>)</a></li>
         <li><a href="#telephone-state-(type=tel)"><span class=secno>4.10.5.1.3 </span>Telephone state (<code title="">type=tel</code>)</a></li>
         <li><a href="#url-state-(type=url)"><span class=secno>4.10.5.1.4 </span>URL state (<code title="">type=url</code>)</a></li>
         <li><a href="#e-mail-state-(type=email)"><span class=secno>4.10.5.1.5 </span>E-mail state (<code title="">type=email</code>)</a></li>
         <li><a href="#password-state-(type=password)"><span class=secno>4.10.5.1.6 </span>Password state (<code title="">type=password</code>)</a></li>
         <li><a href="#date-and-time-state-(type=datetime)"><span class=secno>4.10.5.1.7 </span>Date and Time state (<code title="">type=datetime</code>)</a></li>
         <li><a href="#date-state-(type=date)"><span class=secno>4.10.5.1.8 </span>Date state (<code title="">type=date</code>)</a></li>
         <li><a href="#month-state-(type=month)"><span class=secno>4.10.5.1.9 </span>Month state (<code title="">type=month</code>)</a></li>
         <li><a href="#week-state-(type=week)"><span class=secno>4.10.5.1.10 </span>Week state (<code title="">type=week</code>)</a></li>
         <li><a href="#time-state-(type=time)"><span class=secno>4.10.5.1.11 </span>Time state (<code title="">type=time</code>)</a></li>
         <li><a href="#local-date-and-time-state-(type=datetime-local)"><span class=secno>4.10.5.1.12 </span>Local Date and Time state (<code title="">type=datetime-local</code>)</a></li>
         <li><a href="#number-state-(type=number)"><span class=secno>4.10.5.1.13 </span>Number state (<code title="">type=number</code>)</a></li>
         <li><a href="#range-state-(type=range)"><span class=secno>4.10.5.1.14 </span>Range state (<code title="">type=range</code>)</a></li>
         <li><a href="#color-state-(type=color)"><span class=secno>4.10.5.1.15 </span>Color state (<code title="">type=color</code>)</a></li>
         <li><a href="#checkbox-state-(type=checkbox)"><span class=secno>4.10.5.1.16 </span>Checkbox state (<code title="">type=checkbox</code>)</a></li>
         <li><a href="#radio-button-state-(type=radio)"><span class=secno>4.10.5.1.17 </span>Radio Button state (<code title="">type=radio</code>)</a></li>
         <li><a href="#file-upload-state-(type=file)"><span class=secno>4.10.5.1.18 </span>File Upload state (<code title="">type=file</code>)</a></li>
         <li><a href="#submit-button-state-(type=submit)"><span class=secno>4.10.5.1.19 </span>Submit Button state (<code title="">type=submit</code>)</a></li>
         <li><a href="#image-button-state-(type=image)"><span class=secno>4.10.5.1.20 </span>Image Button state (<code title="">type=image</code>)</a></li>
         <li><a href="#reset-button-state-(type=reset)"><span class=secno>4.10.5.1.21 </span>Reset Button state (<code title="">type=reset</code>)</a></li>
         <li><a href="#button-state-(type=button)"><span class=secno>4.10.5.1.22 </span>Button state (<code title="">type=button</code>)</a></ol></li>
       <li><a href=#input-impl-notes><span class=secno>4.10.5.2 </span>Implemention notes regarding localization of form controls</a></li>
       <li><a href=#common-input-element-attributes><span class=secno>4.10.5.3 </span>Common <code>input</code> element attributes</a>
        <ol>
         <li><a href=#the-maxlength-and-minlength-attributes><span class=secno>4.10.5.3.1 </span>The <code title=attr-input-maxlength>maxlength</code> and <code title=attr-input-minlength>minlength</code> attributes</a></li>
         <li><a href=#the-size-attribute><span class=secno>4.10.5.3.2 </span>The <code title=attr-input-size>size</code> attribute</a></li>
         <li><a href=#the-readonly-attribute><span class=secno>4.10.5.3.3 </span>The <code title=attr-input-readonly>readonly</code> attribute</a></li>
         <li><a href=#the-required-attribute><span class=secno>4.10.5.3.4 </span>The <code title=attr-input-required>required</code> attribute</a></li>
         <li><a href=#the-multiple-attribute><span class=secno>4.10.5.3.5 </span>The <code title=attr-input-multiple>multiple</code> attribute</a></li>
         <li><a href=#the-pattern-attribute><span class=secno>4.10.5.3.6 </span>The <code title=attr-input-pattern>pattern</code> attribute</a></li>
         <li><a href=#the-min-and-max-attributes><span class=secno>4.10.5.3.7 </span>The <code title=attr-input-min>min</code> and <code title=attr-input-max>max</code> attributes</a></li>
         <li><a href=#the-step-attribute><span class=secno>4.10.5.3.8 </span>The <code title=attr-input-step>step</code> attribute</a></li>
         <li><a href=#the-list-attribute><span class=secno>4.10.5.3.9 </span>The <code title=attr-input-list>list</code> attribute</a></li>
         <li><a href=#the-placeholder-attribute><span class=secno>4.10.5.3.10 </span>The <code title=attr-input-placeholder>placeholder</code> attribute</a></ol></li>
       <li><a href=#common-input-element-apis><span class=secno>4.10.5.4 </span>Common <code>input</code> element APIs</a></li>
       <li><a href=#common-event-behaviors><span class=secno>4.10.5.5 </span>Common event behaviors</a></ol></li>
     <li><a href=#the-button-element><span class=secno>4.10.6 </span>The <code>button</code> element</a></li>
     <li><a href=#the-select-element><span class=secno>4.10.7 </span>The <code>select</code> element</a></li>
     <li><a href=#the-datalist-element><span class=secno>4.10.8 </span>The <code>datalist</code> element</a></li>
     <li><a href=#the-optgroup-element><span class=secno>4.10.9 </span>The <code>optgroup</code> element</a></li>
     <li><a href=#the-option-element><span class=secno>4.10.10 </span>The <code>option</code> element</a></li>
     <li><a href=#the-textarea-element><span class=secno>4.10.11 </span>The <code>textarea</code> element</a></li>
     <li><a href=#the-keygen-element><span class=secno>4.10.12 </span>The <code>keygen</code> element</a></li>
     <li><a href=#the-output-element><span class=secno>4.10.13 </span>The <code>output</code> element</a></li>
     <li><a href=#the-progress-element><span class=secno>4.10.14 </span>The <code>progress</code> element</a></li>
     <li><a href=#the-meter-element><span class=secno>4.10.15 </span>The <code>meter</code> element</a></li>
     <li><a href=#the-fieldset-element><span class=secno>4.10.16 </span>The <code>fieldset</code> element</a></li>
     <li><a href=#the-legend-element><span class=secno>4.10.17 </span>The <code>legend</code> element</a></li>
     <li><a href=#form-control-infrastructure><span class=secno>4.10.18 </span>Form control infrastructure</a>
      <ol>
       <li><a href="#a-form-control's-value"><span class=secno>4.10.18.1 </span>A form control's value</a></li>
       <li><a href=#mutability><span class=secno>4.10.18.2 </span>Mutability</a></li>
       <li><a href=#association-of-controls-and-forms><span class=secno>4.10.18.3 </span>Association of controls and forms</a></ol></li>
     <li><a href=#attributes-common-to-form-controls><span class=secno>4.10.19 </span>Attributes common to form controls</a>
      <ol>
       <li><a href=#naming-form-controls:-the-name-attribute><span class=secno>4.10.19.1 </span>Naming form controls: the <code title=attr-fe-name>name</code> attribute</a></li>
       <li><a href=#submitting-element-directionality:-the-dirname-attribute><span class=secno>4.10.19.2 </span>Submitting element directionality: the <code title=attr-fe-dirname>dirname</code> attribute</a></li>
       <li><a href=#limiting-user-input-length:-the-maxlength-attribute><span class=secno>4.10.19.3 </span>Limiting user input length: the <code title=attr-fe-maxlength>maxlength</code> attribute</a></li>
       <li><a href=#setting-minimum-input-length-requirements:-the-minlength-attribute><span class=secno>4.10.19.4 </span>Setting minimum input length requirements: the <code title=attr-fe-minlength>minlength</code> attribute</a></li>
       <li><a href=#enabling-and-disabling-form-controls:-the-disabled-attribute><span class=secno>4.10.19.5 </span>Enabling and disabling form controls: the <code title=attr-fe-disabled>disabled</code> attribute</a></li>
       <li><a href=#form-submission-0><span class=secno>4.10.19.6 </span>Form submission</a></li>
       <li><a href=#autofocusing-a-form-control:-the-autofocus-attribute><span class=secno>4.10.19.7 </span>Autofocusing a form control: the <code title=attr-fe-autofocus>autofocus</code> attribute</a></li>
       <li><a href=#input-modalities:-the-inputmode-attribute><span class=secno>4.10.19.8 </span>Input modalities: the <code title=attr-fe-inputmode>inputmode</code> attribute</a></li>
       <li><a href=#autofilling-form-controls:-the-autocomplete-attribute><span class=secno>4.10.19.9 </span>Autofilling form controls: the <code title=attr-fe-autocomplete>autocomplete</code> attribute</a></ol></li>
     <li><a href=#textFieldSelection><span class=secno>4.10.20 </span>APIs for the text field selections</a></li>
     <li><a href=#constraints><span class=secno>4.10.21 </span>Constraints</a>
      <ol>
       <li><a href=#definitions><span class=secno>4.10.21.1 </span>Definitions</a></li>
       <li><a href=#constraint-validation><span class=secno>4.10.21.2 </span>Constraint validation</a></li>
       <li><a href=#the-constraint-validation-api><span class=secno>4.10.21.3 </span>The constraint validation API</a></li>
       <li><a href=#security-forms><span class=secno>4.10.21.4 </span>Security</a></ol></li>
     <li><a href=#form-submission><span class=secno>4.10.22 </span>Form submission</a>
      <ol>
       <li><a href=#introduction-3><span class=secno>4.10.22.1 </span>Introduction</a></li>
       <li><a href=#implicit-submission><span class=secno>4.10.22.2 </span>Implicit submission</a></li>
       <li><a href=#form-submission-algorithm><span class=secno>4.10.22.3 </span>Form submission algorithm</a></li>
       <li><a href=#constructing-form-data-set><span class=secno>4.10.22.4 </span>Constructing the form data set</a></li>
       <li><a href=#selecting-a-form-submission-encoding><span class=secno>4.10.22.5 </span>Selecting a form submission encoding</a></li>
       <li><a href=#url-encoded-form-data><span class=secno>4.10.22.6 </span>URL-encoded form data</a></li>
       <li><a href=#multipart-form-data><span class=secno>4.10.22.7 </span>Multipart form data</a></li>
       <li><a href=#plain-text-form-data><span class=secno>4.10.22.8 </span>Plain text form data</a></ol></li>
     <li><a href=#resetting-a-form><span class=secno>4.10.23 </span>Resetting a form</a></ol></li>
   <li><a href=#interactive-elements><span class=secno>4.11 </span>Interactive elements</a>
    <ol>
     <li><a href=#the-details-element><span class=secno>4.11.1 </span>The <code>details</code> element</a></li>
     <li><a href=#the-summary-element><span class=secno>4.11.2 </span>The <code>summary</code> element</a></li>
     <li><a href=#the-menu-element><span class=secno>4.11.3 </span>The <code>menu</code> element</a></li>
     <li><a href=#the-menuitem-element><span class=secno>4.11.4 </span>The <code>menuitem</code> element</a></li>
     <li><a href=#context-menus><span class=secno>4.11.5 </span>Context menus</a>
      <ol>
       <li><a href=#declaring-a-context-menu><span class=secno>4.11.5.1 </span>Declaring a context menu</a></li>
       <li><a href=#processing-model-2><span class=secno>4.11.5.2 </span>Processing model</a></li>
       <li><a href=#event-definitions-0><span class=secno>4.11.5.3 </span>Event definitions</a></ol></li>
     <li><a href=#commands><span class=secno>4.11.6 </span>Commands</a>
      <ol>
       <li><a href=#facets-0><span class=secno>4.11.6.1 </span>Facets</a></li>
       <li><a href=#using-the-a-element-to-define-a-command><span class=secno>4.11.6.2 </span>Using the <code>a</code> element to define a command</a></li>
       <li><a href=#using-the-button-element-to-define-a-command><span class=secno>4.11.6.3 </span>Using the <code>button</code> element to define a command</a></li>
       <li><a href=#using-the-input-element-to-define-a-command><span class=secno>4.11.6.4 </span>Using the <code>input</code> element to define a command</a></li>
       <li><a href=#using-the-option-element-to-define-a-command><span class=secno>4.11.6.5 </span>Using the <code>option</code> element to define a command</a></li>
       <li><a href=#using-the-menuitem-element-to-define-a-command><span class=secno>4.11.6.6 </span>Using the <code>menuitem</code> element to define a
  command</a></li>
       <li><a href=#using-the-command-attribute-on-menuitem-elements-to-define-a-command-indirectly><span class=secno>4.11.6.7 </span>Using the <code title=attr-menuitem-command>command</code> attribute on <code>menuitem</code> elements to define
  a command indirectly</a></li>
       <li><a href=#using-the-accesskey-attribute-on-a-label-element-to-define-a-command><span class=secno>4.11.6.8 </span>Using the <code title=attr-accesskey>accesskey</code> attribute
  on a <code>label</code> element to define a command</a></li>
       <li><a href=#using-the-accesskey-attribute-on-a-legend-element-to-define-a-command><span class=secno>4.11.6.9 </span>Using the <code title=attr-accesskey>accesskey</code> attribute
  on a <code>legend</code> element to define a command</a></li>
       <li><a href=#using-the-accesskey-attribute-to-define-a-command-on-other-elements><span class=secno>4.11.6.10 </span>Using the <code title=attr-accesskey>accesskey</code>
  attribute to define a command on other elements</a></ol></li>
     <li><a href=#the-dialog-element><span class=secno>4.11.7 </span>The <code>dialog</code> element</a>
      <ol>
       <li><a href=#anchor-points><span class=secno>4.11.7.1 </span>Anchor points</a></ol></ol></li>
   <li><a href=#scripting-1><span class=secno>4.12 </span>Scripting</a>
    <ol>
     <li><a href=#the-script-element><span class=secno>4.12.1 </span>The <code>script</code> element</a>
      <ol>
       <li><a href=#scriptingLanguages><span class=secno>4.12.1.1 </span>Scripting languages</a></li>
       <li><a href=#restrictions-for-contents-of-script-elements><span class=secno>4.12.1.2 </span>Restrictions for contents of <code>script</code> elements</a></li>
       <li><a href=#inline-documentation-for-external-scripts><span class=secno>4.12.1.3 </span>Inline documentation for external scripts</a></li>
       <li><a href=#scriptTagXSLT><span class=secno>4.12.1.4 </span>Interaction of <code>script</code> elements and XSLT</a></ol></li>
     <li><a href=#the-noscript-element><span class=secno>4.12.2 </span>The <code>noscript</code> element</a></li>
     <li><a href=#the-template-element><span class=secno>4.12.3 </span>The <code>template</code> element</a>
      <ol>
       <li><a href=#template-XSLT-XPath><span class=secno>4.12.3.1 </span>Interaction of <code>template</code> elements with XSLT and XPath</a></ol></li>
     <li><a href=#the-canvas-element><span class=secno>4.12.4 </span>The <code>canvas</code> element</a>
      <ol>
       <li><a href=#proxying-canvases-to-workers><span class=secno>4.12.4.1 </span>Proxying canvases to workers</a></li>
       <li><a href=#2dcontext><span class=secno>4.12.4.2 </span>The 2D rendering context</a>
        <ol>
         <li><a href=#implementation-notes><span class=secno>4.12.4.2.1 </span>Implementation notes</a></li>
         <li><a href=#the-canvas-state><span class=secno>4.12.4.2.2 </span>The canvas state</a></li>
         <li><a href=#drawingstyle-objects><span class=secno>4.12.4.2.3 </span><code>DrawingStyle</code> objects</a></li>
         <li><a href=#line-styles><span class=secno>4.12.4.2.4 </span>Line styles</a></li>
         <li><a href=#text-styles><span class=secno>4.12.4.2.5 </span>Text styles</a></li>
         <li><a href=#building-paths><span class=secno>4.12.4.2.6 </span>Building paths</a></li>
         <li><a href=#path-objects><span class=secno>4.12.4.2.7 </span><code>Path</code> objects</a></li>
         <li><a href=#transformations><span class=secno>4.12.4.2.8 </span>Transformations</a></li>
         <li><a href=#image-sources-for-2d-rendering-contexts><span class=secno>4.12.4.2.9 </span>Image sources for 2D rendering contexts</a></li>
         <li><a href=#fill-and-stroke-styles><span class=secno>4.12.4.2.10 </span>Fill and stroke styles</a></li>
         <li><a href=#drawing-rectangles-to-the-bitmap><span class=secno>4.12.4.2.11 </span>Drawing rectangles to the bitmap</a></li>
         <li><a href=#drawing-text-to-the-bitmap><span class=secno>4.12.4.2.12 </span>Drawing text to the bitmap</a></li>
         <li><a href=#drawing-paths-to-the-canvas><span class=secno>4.12.4.2.13 </span>Drawing paths to the canvas</a></li>
         <li><a href=#drawing-images><span class=secno>4.12.4.2.14 </span>Drawing images</a></li>
         <li><a href=#hit-regions><span class=secno>4.12.4.2.15 </span>Hit regions</a></li>
         <li><a href=#pixel-manipulation><span class=secno>4.12.4.2.16 </span>Pixel manipulation</a></li>
         <li><a href=#compositing><span class=secno>4.12.4.2.17 </span>Compositing</a></li>
         <li><a href=#image-smoothing><span class=secno>4.12.4.2.18 </span>Image smoothing</a></li>
         <li><a href=#shadows><span class=secno>4.12.4.2.19 </span>Shadows</a></li>
         <li><a href=#drawing-model><span class=secno>4.12.4.2.20 </span>Drawing model</a></li>
         <li><a href=#best-practices><span class=secno>4.12.4.2.21 </span>Best practices</a></li>
         <li><a href=#examples-0><span class=secno>4.12.4.2.22 </span>Examples</a></ol></li>
       <li><a href=#pixel-density><span class=secno>4.12.4.3 </span>Pixel density</a></li>
       <li><a href=#color-spaces-and-color-correction><span class=secno>4.12.4.4 </span>Color spaces and color correction</a></li>
       <li><a href=#serializing-bitmaps-to-a-file><span class=secno>4.12.4.5 </span>Serializing bitmaps to a file</a></li>
       <li><a href=#security-with-canvas-elements><span class=secno>4.12.4.6 </span>Security with <code>canvas</code> elements</a></ol></ol></li>
   <li><a href=#common-idioms><span class=secno>4.13 </span>Common idioms without dedicated elements</a>
    <ol>
     <li><a href=#the-main-part-of-the-content><span class=secno>4.13.1 </span>The main part of the content</a></li>
     <li><a href=#rel-up><span class=secno>4.13.2 </span>Bread crumb navigation</a></li>
     <li><a href=#tag-clouds><span class=secno>4.13.3 </span>Tag clouds</a></li>
     <li><a href=#conversations><span class=secno>4.13.4 </span>Conversations</a></li>
     <li><a href=#footnotes><span class=secno>4.13.5 </span>Footnotes</a></ol></li>
   <li><a href=#disabled-elements><span class=secno>4.14 </span>Disabled elements</a></li>
   <li><a href=#selectors><span class=secno>4.15 </span>Matching HTML elements using selectors</a>
    <ol>
     <li><a href=#case-sensitivity><span class=secno>4.15.1 </span>Case-sensitivity</a></li>
     <li><a href=#pseudo-classes><span class=secno>4.15.2 </span>Pseudo-classes</a></ol></ol></li>
 <li><a href=#microdata><span class=secno>5 </span>Microdata</a>
  <ol>
   <li><a href=#introduction-4><span class=secno>5.1 </span>Introduction</a>
    <ol>
     <li><a href=#overview><span class=secno>5.1.1 </span>Overview</a></li>
     <li><a href=#the-basic-syntax><span class=secno>5.1.2 </span>The basic syntax</a></li>
     <li><a href=#typed-items><span class=secno>5.1.3 </span>Typed items</a></li>
     <li><a href=#global-identifiers-for-items><span class=secno>5.1.4 </span>Global identifiers for items</a></li>
     <li><a href=#selecting-names-when-defining-vocabularies><span class=secno>5.1.5 </span>Selecting names when defining vocabularies</a></li>
     <li><a href=#using-the-microdata-dom-api><span class=secno>5.1.6 </span>Using the microdata DOM API</a></ol></li>
   <li><a href=#encoding-microdata><span class=secno>5.2 </span>Encoding microdata</a>
    <ol>
     <li><a href=#the-microdata-model><span class=secno>5.2.1 </span>The microdata model</a></li>
     <li><a href=#items><span class=secno>5.2.2 </span>Items</a></li>
     <li><a href=#names:-the-itemprop-attribute><span class=secno>5.2.3 </span>Names: the <code>itemprop</code> attribute</a></li>
     <li><a href=#values><span class=secno>5.2.4 </span>Values</a></li>
     <li><a href=#associating-names-with-items><span class=secno>5.2.5 </span>Associating names with items</a></li>
     <li><a href=#microdata-and-other-namespaces><span class=secno>5.2.6 </span>Microdata and other namespaces</a></ol></li>
   <li><a href=#microdata-dom-api><span class=secno>5.3 </span>Microdata DOM API</a></li>
   <li><a href=#mdvocabs><span class=secno>5.4 </span>Sample microdata vocabularies</a>
    <ol>
     <li><a href=#vcard><span class=secno>5.4.1 </span>vCard</a>
      <ol>
       <li><a href=#conversion-to-vcard><span class=secno>5.4.1.1 </span>Conversion to vCard</a></li>
       <li><a href=#examples-1><span class=secno>5.4.1.2 </span>Examples</a></ol></li>
     <li><a href=#vevent><span class=secno>5.4.2 </span>vEvent</a>
      <ol>
       <li><a href=#conversion-to-icalendar><span class=secno>5.4.2.1 </span>Conversion to iCalendar</a></li>
       <li><a href=#examples-2><span class=secno>5.4.2.2 </span>Examples</a></ol></li>
     <li><a href=#licensing-works><span class=secno>5.4.3 </span>Licensing works</a>
      <ol>
       <li><a href=#examples-3><span class=secno>5.4.3.1 </span>Examples</a></ol></ol></li>
   <li><a href=#converting-html-to-other-formats><span class=secno>5.5 </span>Converting HTML to other formats</a>
    <ol>
     <li><a href=#json><span class=secno>5.5.1 </span>JSON</a></ol></ol></li>
 <li><a href=#browsers><span class=secno>6 </span>Loading Web pages</a>
  <ol>
   <li><a href=#windows><span class=secno>6.1 </span>Browsing contexts</a>
    <ol>
     <li><a href=#nested-browsing-contexts><span class=secno>6.1.1 </span>Nested browsing contexts</a>
      <ol>
       <li><a href=#navigating-nested-browsing-contexts-in-the-dom><span class=secno>6.1.1.1 </span>Navigating nested browsing contexts in the DOM</a></ol></li>
     <li><a href=#auxiliary-browsing-contexts><span class=secno>6.1.2 </span>Auxiliary browsing contexts</a>
      <ol>
       <li><a href=#navigating-auxiliary-browsing-contexts-in-the-dom><span class=secno>6.1.2.1 </span>Navigating auxiliary browsing contexts in the DOM</a></ol></li>
     <li><a href=#secondary-browsing-contexts><span class=secno>6.1.3 </span>Secondary browsing contexts</a></li>
     <li><a href=#security-nav><span class=secno>6.1.4 </span>Security</a></li>
     <li><a href=#groupings-of-browsing-contexts><span class=secno>6.1.5 </span>Groupings of browsing contexts</a></li>
     <li><a href=#browsing-context-names><span class=secno>6.1.6 </span>Browsing context names</a></ol></li>
   <li><a href=#the-window-object><span class=secno>6.2 </span>The <code>Window</code> object</a>
    <ol>
     <li><a href=#security-window><span class=secno>6.2.1 </span>Security</a></li>
     <li><a href=#apis-for-creating-and-navigating-browsing-contexts-by-name><span class=secno>6.2.2 </span>APIs for creating and navigating browsing contexts by name</a></li>
     <li><a href=#accessing-other-browsing-contexts><span class=secno>6.2.3 </span>Accessing other browsing contexts</a></li>
     <li><a href=#named-access-on-the-window-object><span class=secno>6.2.4 </span>Named access on the <code>Window</code> object</a></li>
     <li><a href=#garbage-collection-and-browsing-contexts><span class=secno>6.2.5 </span>Garbage collection and browsing contexts</a></li>
     <li><a href=#closing-browsing-contexts><span class=secno>6.2.6 </span>Closing browsing contexts</a></li>
     <li><a href=#browser-interface-elements><span class=secno>6.2.7 </span>Browser interface elements</a></li>
     <li><a href=#the-windowproxy-object><span class=secno>6.2.8 </span>The <code>WindowProxy</code> object</a></ol></li>
   <li><a href=#origin-0><span class=secno>6.3 </span>Origin</a>
    <ol>
     <li><a href=#relaxing-the-same-origin-restriction><span class=secno>6.3.1 </span>Relaxing the same-origin restriction</a></ol></li>
   <li><a href=#sandboxing><span class=secno>6.4 </span>Sandboxing</a></li>
   <li><a href=#history><span class=secno>6.5 </span>Session history and navigation</a>
    <ol>
     <li><a href=#the-session-history-of-browsing-contexts><span class=secno>6.5.1 </span>The session history of browsing contexts</a></li>
     <li><a href=#the-history-interface><span class=secno>6.5.2 </span>The <code>History</code> interface</a></li>
     <li><a href=#the-location-interface><span class=secno>6.5.3 </span>The <code>Location</code> interface</a>
      <ol>
       <li><a href=#security-location><span class=secno>6.5.3.1 </span>Security</a></ol></li>
     <li><a href=#history-notes><span class=secno>6.5.4 </span>Implementation notes for session history</a></ol></li>
   <li><a href=#browsing-the-web><span class=secno>6.6 </span>Browsing the Web</a>
    <ol>
     <li><a href=#navigating-across-documents><span class=secno>6.6.1 </span>Navigating across documents</a></li>
     <li><a href=#read-html><span class=secno>6.6.2 </span>Page load processing model for HTML files</a></li>
     <li><a href=#read-xml><span class=secno>6.6.3 </span>Page load processing model for XML files</a></li>
     <li><a href=#read-text><span class=secno>6.6.4 </span>Page load processing model for text files</a></li>
     <li><a href=#read-multipart-x-mixed-replace><span class=secno>6.6.5 </span>Page load processing model for <code>multipart/x-mixed-replace</code> resources</a></li>
     <li><a href=#read-media><span class=secno>6.6.6 </span>Page load processing model for media</a></li>
     <li><a href=#read-plugin><span class=secno>6.6.7 </span>Page load processing model for content that uses plugins</a></li>
     <li><a href=#read-ua-inline><span class=secno>6.6.8 </span>Page load processing model for inline
  content that doesn't have a DOM</a></li>
     <li><a href=#scroll-to-fragid><span class=secno>6.6.9 </span>Navigating to a fragment identifier</a></li>
     <li><a href=#history-traversal><span class=secno>6.6.10 </span>History traversal</a>
      <ol>
       <li><a href=#event-definitions-1><span class=secno>6.6.10.1 </span>Event definitions</a></ol></li>
     <li><a href=#unloading-documents><span class=secno>6.6.11 </span>Unloading documents</a>
      <ol>
       <li><a href=#event-definition><span class=secno>6.6.11.1 </span>Event definition</a></ol></li>
     <li><a href=#aborting-a-document-load><span class=secno>6.6.12 </span>Aborting a document load</a></ol></li>
   <li><a href=#offline><span class=secno>6.7 </span>Offline Web applications</a>
    <ol>
     <li><a href=#introduction-5><span class=secno>6.7.1 </span>Introduction</a>
      <ol>
       <li><a href=#supporting-offline-caching-for-legacy-applications><span class=secno>6.7.1.1 </span>Supporting offline caching for legacy applications</a></li>
       <li><a href=#appcacheevents><span class=secno>6.7.1.2 </span>Event summary</a></ol></li>
     <li><a href=#appcache><span class=secno>6.7.2 </span>Application caches</a></li>
     <li><a href=#manifests><span class=secno>6.7.3 </span>The cache manifest syntax</a>
      <ol>
       <li><a href=#some-sample-manifests><span class=secno>6.7.3.1 </span>Some sample manifests</a></li>
       <li><a href=#writing-cache-manifests><span class=secno>6.7.3.2 </span>Writing cache manifests</a></li>
       <li><a href=#parsing-cache-manifests><span class=secno>6.7.3.3 </span>Parsing cache manifests</a></ol></li>
     <li><a href=#downloading-or-updating-an-application-cache><span class=secno>6.7.4 </span>Downloading or updating an application cache</a></li>
     <li><a href=#the-application-cache-selection-algorithm><span class=secno>6.7.5 </span>The application cache selection algorithm</a></li>
     <li><a href=#changesToNetworkingModel><span class=secno>6.7.6 </span>Changes to the networking model</a></li>
     <li><a href=#expiring-application-caches><span class=secno>6.7.7 </span>Expiring application caches</a></li>
     <li><a href=#disk-space><span class=secno>6.7.8 </span>Disk space</a></li>
     <li><a href=#application-cache-api><span class=secno>6.7.9 </span>Application cache API</a></li>
     <li><a href=#browser-state><span class=secno>6.7.10 </span>Browser state</a></ol></ol></li>
 <li><a href=#webappapis><span class=secno>7 </span>Web application APIs</a>
  <ol>
   <li><a href=#scripting><span class=secno>7.1 </span>Scripting</a>
    <ol>
     <li><a href=#introduction-6><span class=secno>7.1.1 </span>Introduction</a></li>
     <li><a href=#enabling-and-disabling-scripting><span class=secno>7.1.2 </span>Enabling and disabling scripting</a></li>
     <li><a href=#processing-model-3><span class=secno>7.1.3 </span>Processing model</a>
      <ol>
       <li><a href=#definitions-0><span class=secno>7.1.3.1 </span>Definitions</a></li>
       <li><a href=#script-settings-for-browsing-contexts><span class=secno>7.1.3.2 </span>Script settings for browsing contexts</a></li>
       <li><a href=#calling-scripts><span class=secno>7.1.3.3 </span>Calling scripts</a></li>
       <li><a href=#creating-scripts><span class=secno>7.1.3.4 </span>Creating scripts</a></li>
       <li><a href=#killing-scripts><span class=secno>7.1.3.5 </span>Killing scripts</a></li>
       <li><a href=#runtime-script-errors><span class=secno>7.1.3.6 </span>Runtime script errors</a>
        <ol>
         <li><a href=#runtime-script-errors-in-documents><span class=secno>7.1.3.6.1 </span>Runtime script errors in documents</a></li>
         <li><a href=#the-errorevent-interface><span class=secno>7.1.3.6.2 </span>The <code>ErrorEvent</code> interface</a></ol></ol></li>
     <li><a href=#event-loops><span class=secno>7.1.4 </span>Event loops</a>
      <ol>
       <li><a href=#definitions-1><span class=secno>7.1.4.1 </span>Definitions</a></li>
       <li><a href=#processing-model-4><span class=secno>7.1.4.2 </span>Processing model</a></li>
       <li><a href=#generic-task-sources><span class=secno>7.1.4.3 </span>Generic task sources</a></ol></li>
     <li><a href=#javascript-protocol><span class=secno>7.1.5 </span>The <code title="">javascript:</code> URL scheme</a></li>
     <li><a href=#events><span class=secno>7.1.6 </span>Events</a>
      <ol>
       <li><a href=#event-handler-attributes><span class=secno>7.1.6.1 </span>Event handlers</a></li>
       <li><a href=#event-handlers-on-elements,-document-objects,-and-window-objects><span class=secno>7.1.6.2 </span>Event handlers on elements, <code>Document</code> objects, and <code>Window</code> objects</a>
        <ol>
         <li><a href=#idl-definitions><span class=secno>7.1.6.2.1 </span>IDL definitions</a></ol></li>
       <li><a href=#event-firing><span class=secno>7.1.6.3 </span>Event firing</a></li>
       <li><a href=#events-and-the-window-object><span class=secno>7.1.6.4 </span>Events and the <code>Window</code> object</a></ol></ol></li>
   <li><a href=#atob><span class=secno>7.2 </span>Base64 utility methods</a></li>
   <li><a href=#dynamic-markup-insertion><span class=secno>7.3 </span>Dynamic markup insertion</a>
    <ol>
     <li><a href=#opening-the-input-stream><span class=secno>7.3.1 </span>Opening the input stream</a></li>
     <li><a href=#closing-the-input-stream><span class=secno>7.3.2 </span>Closing the input stream</a></li>
     <li><a href=#document.write()><span class=secno>7.3.3 </span><code title=dom-document-write>document.write()</code></a></li>
     <li><a href=#document.writeln()><span class=secno>7.3.4 </span><code title=dom-document-writeln>document.writeln()</code></a></ol></li>
   <li><a href=#timers><span class=secno>7.4 </span>Timers</a></li>
   <li><a href=#user-prompts><span class=secno>7.5 </span>User prompts</a>
    <ol>
     <li><a href=#simple-dialogs><span class=secno>7.5.1 </span>Simple dialogs</a></li>
     <li><a href=#printing><span class=secno>7.5.2 </span>Printing</a></li>
     <li><a href=#dialogs-implemented-using-separate-documents><span class=secno>7.5.3 </span>Dialogs implemented using separate documents</a></ol></li>
   <li><a href=#system-state-and-capabilities><span class=secno>7.6 </span>System state and capabilities</a>
    <ol>
     <li><a href=#the-navigator-object><span class=secno>7.6.1 </span>The <code>Navigator</code> object</a>
      <ol>
       <li><a href=#client-identification><span class=secno>7.6.1.1 </span>Client identification</a></li>
       <li><a href=#language-preferences><span class=secno>7.6.1.2 </span>Language preferences</a></li>
       <li><a href=#custom-handlers><span class=secno>7.6.1.3 </span>Custom scheme and content handlers</a>
        <ol>
         <li><a href=#security-and-privacy><span class=secno>7.6.1.3.1 </span>Security and privacy</a></li>
         <li><a href=#sample-handler-impl><span class=secno>7.6.1.3.2 </span>Sample user interface</a></ol></li>
       <li><a href=#manually-releasing-the-storage-mutex><span class=secno>7.6.1.4 </span>Manually releasing the storage mutex</a></li>
       <li><a href=#plugins-0><span class=secno>7.6.1.5 </span>Plugins</a></ol></li>
     <li><a href=#the-external-interface><span class=secno>7.6.2 </span>The <code>External</code> interface</a></ol></li>
   <li><a href=#images><span class=secno>7.7 </span>Images</a></ol></li>
 <li><a href=#editing><span class=secno>8 </span>User interaction</a>
  <ol>
   <li><a href=#the-hidden-attribute><span class=secno>8.1 </span>The <code>hidden</code> attribute</a></li>
   <li><a href=#inert-subtrees><span class=secno>8.2 </span>Inert subtrees</a>
    <ol>
     <li><a href=#the-inert-attribute><span class=secno>8.2.1 </span>The <code>inert</code> attribute</a></ol></li>
   <li><a href=#activation><span class=secno>8.3 </span>Activation</a></li>
   <li><a href=#focus><span class=secno>8.4 </span>Focus</a>
    <ol>
     <li><a href=#sequential-focus-navigation-and-the-tabindex-attribute><span class=secno>8.4.1 </span>Sequential focus navigation and the <code title=attr-tabindex>tabindex</code> attribute</a></li>
     <li><a href=#focus-management><span class=secno>8.4.2 </span>Focus management</a></li>
     <li><a href=#document-level-focus-apis><span class=secno>8.4.3 </span>Document-level focus APIs</a></li>
     <li><a href=#element-level-focus-apis><span class=secno>8.4.4 </span>Element-level focus APIs</a></ol></li>
   <li><a href=#assigning-keyboard-shortcuts><span class=secno>8.5 </span>Assigning keyboard shortcuts</a>
    <ol>
     <li><a href=#introduction-7><span class=secno>8.5.1 </span>Introduction</a></li>
     <li><a href=#the-accesskey-attribute><span class=secno>8.5.2 </span>The <code>accesskey</code> attribute</a></li>
     <li><a href=#processing-model-5><span class=secno>8.5.3 </span>Processing model</a></ol></li>
   <li><a href=#editing-0><span class=secno>8.6 </span>Editing</a>
    <ol>
     <li><a href=#contenteditable><span class=secno>8.6.1 </span>Making document regions editable: The <code title=attr-contenteditable>contenteditable</code> content attribute</a></li>
     <li><a href=#making-entire-documents-editable:-the-designmode-idl-attribute><span class=secno>8.6.2 </span>Making entire documents editable: The <code title=dom-document-designMode>designMode</code> IDL attribute</a></li>
     <li><a href=#best-practices-for-in-page-editors><span class=secno>8.6.3 </span>Best practices for in-page editors</a></li>
     <li><a href=#editing-apis><span class=secno>8.6.4 </span>Editing APIs</a></li>
     <li><a href=#spelling-and-grammar-checking><span class=secno>8.6.5 </span>Spelling and grammar checking</a></ol></li>
   <li><a href=#dnd><span class=secno>8.7 </span>Drag and drop</a>
    <ol>
     <li><a href=#introduction-8><span class=secno>8.7.1 </span>Introduction</a></li>
     <li><a href=#the-drag-data-store><span class=secno>8.7.2 </span>The drag data store</a></li>
     <li><a href=#the-datatransfer-interface><span class=secno>8.7.3 </span>The <code>DataTransfer</code> interface</a>
      <ol>
       <li><a href=#the-datatransferitemlist-interface><span class=secno>8.7.3.1 </span>The <code>DataTransferItemList</code> interface</a></li>
       <li><a href=#the-datatransferitem-interface><span class=secno>8.7.3.2 </span>The <code>DataTransferItem</code> interface</a></ol></li>
     <li><a href=#the-dragevent-interface><span class=secno>8.7.4 </span>The <code>DragEvent</code> interface</a></li>
     <li><a href=#drag-and-drop-processing-model><span class=secno>8.7.5 </span>Drag-and-drop processing model</a></li>
     <li><a href=#dndevents><span class=secno>8.7.6 </span>Events summary</a></li>
     <li><a href=#the-draggable-attribute><span class=secno>8.7.7 </span>The <code>draggable</code> attribute</a></li>
     <li><a href=#the-dropzone-attribute><span class=secno>8.7.8 </span>The <code>dropzone</code> attribute</a></li>
     <li><a href=#security-risks-in-the-drag-and-drop-model><span class=secno>8.7.9 </span>Security risks in the drag-and-drop model</a></ol></ol></li>
 <li><a href=#comms><span class=secno>9 </span>Communication</a>
  <ol>
   <li><a href=#event-definitions-2><span class=secno>9.1 </span>Event definitions</a></li>
   <li><a href=#server-sent-events><span class=secno>9.2 </span>Server-sent events</a>
    <ol>
     <li><a href=#server-sent-events-intro><span class=secno>9.2.1 </span>Introduction</a></li>
     <li><a href=#the-eventsource-interface><span class=secno>9.2.2 </span>The <code>EventSource</code> interface</a></li>
     <li><a href=#processing-model-6><span class=secno>9.2.3 </span>Processing model</a></li>
     <li><a href=#parsing-an-event-stream><span class=secno>9.2.4 </span>Parsing an event stream</a></li>
     <li><a href=#event-stream-interpretation><span class=secno>9.2.5 </span>Interpreting an event stream</a></li>
     <li><a href=#authoring-notes><span class=secno>9.2.6 </span>Authoring notes</a></li>
     <li><a href=#eventsource-push><span class=secno>9.2.7 </span>Connectionless push and other features</a></li>
     <li><a href=#garbage-collection-0><span class=secno>9.2.8 </span>Garbage collection</a></li>
     <li><a href=#implementation-advice><span class=secno>9.2.9 </span>Implementation advice</a></li>
     <li><a href=#iana-considerations><span class=secno>9.2.10 </span>IANA considerations</a>
      <ol>
       <li><a href=#text/event-stream><span class=secno>9.2.10.1 </span><code>text/event-stream</code></a></li>
       <li><a href=#last-event-id><span class=secno>9.2.10.2 </span><code>Last-Event-ID</code></a></ol></ol></li>
   <li><a href=#network><span class=secno>9.3 </span>Web sockets</a>
    <ol>
     <li><a href=#network-intro><span class=secno>9.3.1 </span>Introduction</a></li>
     <li><a href=#the-websocket-interface><span class=secno>9.3.2 </span>The <code>WebSocket</code> interface</a></li>
     <li><a href=#feedback-from-the-protocol><span class=secno>9.3.3 </span>Feedback from the protocol</a></li>
     <li><a href=#ping-and-pong-frames><span class=secno>9.3.4 </span>Ping and Pong frames</a></li>
     <li><a href=#parsing-websocket-urls><span class=secno>9.3.5 </span>Parsing WebSocket URLs</a></li>
     <li><a href=#event-definitions-3><span class=secno>9.3.6 </span>Event definitions</a></li>
     <li><a href=#garbage-collection-1><span class=secno>9.3.7 </span>Garbage collection</a></ol></li>
   <li><a href=#web-messaging><span class=secno>9.4 </span>Cross-document messaging</a>
    <ol>
     <li><a href=#introduction-9><span class=secno>9.4.1 </span>Introduction</a></li>
     <li><a href=#security-postmsg><span class=secno>9.4.2 </span>Security</a>
      <ol>
       <li><a href=#authors><span class=secno>9.4.2.1 </span>Authors</a></li>
       <li><a href=#user-agents><span class=secno>9.4.2.2 </span>User agents</a></ol></li>
     <li><a href=#posting-messages><span class=secno>9.4.3 </span>Posting messages</a></ol></li>
   <li><a href=#channel-messaging><span class=secno>9.5 </span>Channel messaging</a>
    <ol>
     <li><a href=#introduction-10><span class=secno>9.5.1 </span>Introduction</a>
      <ol>
       <li><a href=#examples-4><span class=secno>9.5.1.1 </span>Examples</a></li>
       <li><a href=#ports-as-the-basis-of-an-object-capability-model-on-the-web><span class=secno>9.5.1.2 </span>Ports as the basis of an object-capability model on the Web</a></li>
       <li><a href=#ports-as-the-basis-of-abstracting-out-service-implementations><span class=secno>9.5.1.3 </span>Ports as the basis of abstracting out service implementations</a></ol></li>
     <li><a href=#message-channels><span class=secno>9.5.2 </span>Message channels</a></li>
     <li><a href=#message-ports><span class=secno>9.5.3 </span>Message ports</a></li>
     <li><a href=#broadcasting-to-many-ports><span class=secno>9.5.4 </span>Broadcasting to many ports</a></li>
     <li><a href=#ports-and-garbage-collection><span class=secno>9.5.5 </span>Ports and garbage collection</a></ol></ol></li>
 <li><a href=#workers><span class=secno>10 </span>Web workers</a>
  <ol>
   <li><a href=#introduction-11><span class=secno>10.1 </span>Introduction</a>
    <ol>
     <li><a href=#scope-0><span class=secno>10.1.1 </span>Scope</a></li>
     <li><a href=#examples-5><span class=secno>10.1.2 </span>Examples</a>
      <ol>
       <li><a href=#a-background-number-crunching-worker><span class=secno>10.1.2.1 </span>A background number-crunching worker</a></li>
       <li><a href=#worker-used-for-background-i/o><span class=secno>10.1.2.2 </span>Worker used for background I/O</a></li>
       <li><a href=#shared-workers-introduction><span class=secno>10.1.2.3 </span>Shared workers introduction</a></li>
       <li><a href=#shared-state-using-a-shared-worker><span class=secno>10.1.2.4 </span>Shared state using a shared worker</a></li>
       <li><a href=#delegation><span class=secno>10.1.2.5 </span>Delegation</a></ol></li>
     <li><a href=#tutorials><span class=secno>10.1.3 </span>Tutorials</a>
      <ol>
       <li><a href=#creating-a-dedicated-worker><span class=secno>10.1.3.1 </span>Creating a dedicated worker</a></li>
       <li><a href=#communicating-with-a-dedicated-worker><span class=secno>10.1.3.2 </span>Communicating with a dedicated worker</a></li>
       <li><a href=#shared-workers><span class=secno>10.1.3.3 </span>Shared workers</a></ol></ol></li>
   <li><a href=#infrastructure-0><span class=secno>10.2 </span>Infrastructure</a>
    <ol>
     <li><a href=#the-global-scope><span class=secno>10.2.1 </span>The global scope</a>
      <ol>
       <li><a href=#the-workerglobalscope-common-interface><span class=secno>10.2.1.1 </span>The <code>WorkerGlobalScope</code> common interface</a></li>
       <li><a href=#dedicated-workers-and-the-dedicatedworkerglobalscope-interface><span class=secno>10.2.1.2 </span>Dedicated workers and the <code>DedicatedWorkerGlobalScope</code> interface</a></li>
       <li><a href=#shared-workers-and-the-sharedworkerglobalscope-interface><span class=secno>10.2.1.3 </span>Shared workers and the <code>SharedWorkerGlobalScope</code> interface</a></ol></li>
     <li><a href=#the-event-loop><span class=secno>10.2.2 </span>The event loop</a></li>
     <li><a href="#the-worker's-lifetime"><span class=secno>10.2.3 </span>The worker's lifetime</a></li>
     <li><a href=#processing-model-7><span class=secno>10.2.4 </span>Processing model</a></li>
     <li><a href=#runtime-script-errors-0><span class=secno>10.2.5 </span>Runtime script errors</a></li>
     <li><a href=#creating-workers><span class=secno>10.2.6 </span>Creating workers</a>
      <ol>
       <li><a href=#the-abstractworker-abstract-interface><span class=secno>10.2.6.1 </span>The <code>AbstractWorker</code> abstract interface</a></li>
       <li><a href=#script-settings-for-workers><span class=secno>10.2.6.2 </span>Script settings for workers</a></li>
       <li><a href=#dedicated-workers-and-the-worker-interface><span class=secno>10.2.6.3 </span>Dedicated workers and the <code>Worker</code> interface</a></li>
       <li><a href=#shared-workers-and-the-sharedworker-interface><span class=secno>10.2.6.4 </span>Shared workers and the <code>SharedWorker</code> interface</a></ol></ol></li>
   <li><a href=#apis-available-to-workers><span class=secno>10.3 </span>APIs available to workers</a>
    <ol>
     <li><a href=#importing-scripts-and-libraries><span class=secno>10.3.1 </span>Importing scripts and libraries</a></li>
     <li><a href=#the-workernavigator-object><span class=secno>10.3.2 </span>The <code>WorkerNavigator</code> object</a></li>
     <li><a href=#interface-objects-and-constructors><span class=secno>10.3.3 </span>Interface objects and constructors</a></li>
     <li><a href=#worker-locations><span class=secno>10.3.4 </span>Worker locations</a></ol></ol></li>
 <li><a href=#webstorage><span class=secno>11 </span>Web storage</a>
  <ol>
   <li><a href=#introduction-12><span class=secno>11.1 </span>Introduction</a></li>
   <li><a href=#storage><span class=secno>11.2 </span>The API</a>
    <ol>
     <li><a href=#the-storage-interface><span class=secno>11.2.1 </span>The <code>Storage</code> interface</a></li>
     <li><a href=#the-sessionstorage-attribute><span class=secno>11.2.2 </span>The <code title=dom-sessionStorage>sessionStorage</code> attribute</a></li>
     <li><a href=#the-localstorage-attribute><span class=secno>11.2.3 </span>The <code title=dom-localStorage>localStorage</code> attribute</a></li>
     <li><a href=#the-storage-event><span class=secno>11.2.4 </span>The <code title=event-storage>storage</code> event</a>
      <ol>
       <li><a href=#event-definition-0><span class=secno>11.2.4.1 </span>Event definition</a></ol></li>
     <li><a href=#threads><span class=secno>11.2.5 </span>Threads</a></ol></li>
   <li><a href=#disk-space-0><span class=secno>11.3 </span>Disk space</a></li>
   <li><a href=#privacy><span class=secno>11.4 </span>Privacy</a>
    <ol>
     <li><a href=#user-tracking><span class=secno>11.4.1 </span>User tracking</a></li>
     <li><a href=#sensitivity-of-data><span class=secno>11.4.2 </span>Sensitivity of data</a></ol></li>
   <li><a href=#security-storage><span class=secno>11.5 </span>Security</a>
    <ol>
     <li><a href=#dns-spoofing-attacks><span class=secno>11.5.1 </span>DNS spoofing attacks</a></li>
     <li><a href=#cross-directory-attacks><span class=secno>11.5.2 </span>Cross-directory attacks</a></li>
     <li><a href=#implementation-risks><span class=secno>11.5.3 </span>Implementation risks</a></ol></ol></li>
 <li><a href=#syntax><span class=secno>12 </span>The HTML syntax</a>
  <ol>
   <li><a href=#writing><span class=secno>12.1 </span>Writing HTML documents</a>
    <ol>
     <li><a href=#the-doctype><span class=secno>12.1.1 </span>The DOCTYPE</a></li>
     <li><a href=#elements-0><span class=secno>12.1.2 </span>Elements</a>
      <ol>
       <li><a href=#start-tags><span class=secno>12.1.2.1 </span>Start tags</a></li>
       <li><a href=#end-tags><span class=secno>12.1.2.2 </span>End tags</a></li>
       <li><a href=#attributes-0><span class=secno>12.1.2.3 </span>Attributes</a></li>
       <li><a href=#optional-tags><span class=secno>12.1.2.4 </span>Optional tags</a></li>
       <li><a href=#element-restrictions><span class=secno>12.1.2.5 </span>Restrictions on content models</a></li>
       <li><a href=#cdata-rcdata-restrictions><span class=secno>12.1.2.6 </span>Restrictions on the contents of raw text and escapable raw text elements</a></ol></li>
     <li><a href=#text-0><span class=secno>12.1.3 </span>Text</a>
      <ol>
       <li><a href=#newlines><span class=secno>12.1.3.1 </span>Newlines</a></ol></li>
     <li><a href=#character-references><span class=secno>12.1.4 </span>Character references</a></li>
     <li><a href=#cdata-sections><span class=secno>12.1.5 </span>CDATA sections</a></li>
     <li><a href=#comments><span class=secno>12.1.6 </span>Comments</a></ol></li>
   <li><a href=#parsing><span class=secno>12.2 </span>Parsing HTML documents</a>
    <ol>
     <li><a href=#overview-of-the-parsing-model><span class=secno>12.2.1 </span>Overview of the parsing model</a></li>
     <li><a href=#the-input-byte-stream><span class=secno>12.2.2 </span>The input byte stream</a>
      <ol>
       <li><a href=#parsing-with-a-known-character-encoding><span class=secno>12.2.2.1 </span>Parsing with a known character encoding</a></li>
       <li><a href=#determining-the-character-encoding><span class=secno>12.2.2.2 </span>Determining the character encoding</a></li>
       <li><a href=#character-encodings><span class=secno>12.2.2.3 </span>Character encodings</a></li>
       <li><a href=#changing-the-encoding-while-parsing><span class=secno>12.2.2.4 </span>Changing the encoding while parsing</a></li>
       <li><a href=#preprocessing-the-input-stream><span class=secno>12.2.2.5 </span>Preprocessing the input stream</a></ol></li>
     <li><a href=#parse-state><span class=secno>12.2.3 </span>Parse state</a>
      <ol>
       <li><a href=#the-insertion-mode><span class=secno>12.2.3.1 </span>The insertion mode</a></li>
       <li><a href=#the-stack-of-open-elements><span class=secno>12.2.3.2 </span>The stack of open elements</a></li>
       <li><a href=#the-list-of-active-formatting-elements><span class=secno>12.2.3.3 </span>The list of active formatting elements</a></li>
       <li><a href=#the-element-pointers><span class=secno>12.2.3.4 </span>The element pointers</a></li>
       <li><a href=#other-parsing-state-flags><span class=secno>12.2.3.5 </span>Other parsing state flags</a></ol></li>
     <li><a href=#tokenization><span class=secno>12.2.4 </span>Tokenization</a>
      <ol>
       <li><a href=#data-state><span class=secno>12.2.4.1 </span>Data state</a></li>
       <li><a href=#character-reference-in-data-state><span class=secno>12.2.4.2 </span>Character reference in data state</a></li>
       <li><a href=#rcdata-state><span class=secno>12.2.4.3 </span>RCDATA state</a></li>
       <li><a href=#character-reference-in-rcdata-state><span class=secno>12.2.4.4 </span>Character reference in RCDATA state</a></li>
       <li><a href=#rawtext-state><span class=secno>12.2.4.5 </span>RAWTEXT state</a></li>
       <li><a href=#script-data-state><span class=secno>12.2.4.6 </span>Script data state</a></li>
       <li><a href=#plaintext-state><span class=secno>12.2.4.7 </span>PLAINTEXT state</a></li>
       <li><a href=#tag-open-state><span class=secno>12.2.4.8 </span>Tag open state</a></li>
       <li><a href=#end-tag-open-state><span class=secno>12.2.4.9 </span>End tag open state</a></li>
       <li><a href=#tag-name-state><span class=secno>12.2.4.10 </span>Tag name state</a></li>
       <li><a href=#rcdata-less-than-sign-state><span class=secno>12.2.4.11 </span>RCDATA less-than sign state</a></li>
       <li><a href=#rcdata-end-tag-open-state><span class=secno>12.2.4.12 </span>RCDATA end tag open state</a></li>
       <li><a href=#rcdata-end-tag-name-state><span class=secno>12.2.4.13 </span>RCDATA end tag name state</a></li>
       <li><a href=#rawtext-less-than-sign-state><span class=secno>12.2.4.14 </span>RAWTEXT less-than sign state</a></li>
       <li><a href=#rawtext-end-tag-open-state><span class=secno>12.2.4.15 </span>RAWTEXT end tag open state</a></li>
       <li><a href=#rawtext-end-tag-name-state><span class=secno>12.2.4.16 </span>RAWTEXT end tag name state</a></li>
       <li><a href=#script-data-less-than-sign-state><span class=secno>12.2.4.17 </span>Script data less-than sign state</a></li>
       <li><a href=#script-data-end-tag-open-state><span class=secno>12.2.4.18 </span>Script data end tag open state</a></li>
       <li><a href=#script-data-end-tag-name-state><span class=secno>12.2.4.19 </span>Script data end tag name state</a></li>
       <li><a href=#script-data-escape-start-state><span class=secno>12.2.4.20 </span>Script data escape start state</a></li>
       <li><a href=#script-data-escape-start-dash-state><span class=secno>12.2.4.21 </span>Script data escape start dash state</a></li>
       <li><a href=#script-data-escaped-state><span class=secno>12.2.4.22 </span>Script data escaped state</a></li>
       <li><a href=#script-data-escaped-dash-state><span class=secno>12.2.4.23 </span>Script data escaped dash state</a></li>
       <li><a href=#script-data-escaped-dash-dash-state><span class=secno>12.2.4.24 </span>Script data escaped dash dash state</a></li>
       <li><a href=#script-data-escaped-less-than-sign-state><span class=secno>12.2.4.25 </span>Script data escaped less-than sign state</a></li>
       <li><a href=#script-data-escaped-end-tag-open-state><span class=secno>12.2.4.26 </span>Script data escaped end tag open state</a></li>
       <li><a href=#script-data-escaped-end-tag-name-state><span class=secno>12.2.4.27 </span>Script data escaped end tag name state</a></li>
       <li><a href=#script-data-double-escape-start-state><span class=secno>12.2.4.28 </span>Script data double escape start state</a></li>
       <li><a href=#script-data-double-escaped-state><span class=secno>12.2.4.29 </span>Script data double escaped state</a></li>
       <li><a href=#script-data-double-escaped-dash-state><span class=secno>12.2.4.30 </span>Script data double escaped dash state</a></li>
       <li><a href=#script-data-double-escaped-dash-dash-state><span class=secno>12.2.4.31 </span>Script data double escaped dash dash state</a></li>
       <li><a href=#script-data-double-escaped-less-than-sign-state><span class=secno>12.2.4.32 </span>Script data double escaped less-than sign state</a></li>
       <li><a href=#script-data-double-escape-end-state><span class=secno>12.2.4.33 </span>Script data double escape end state</a></li>
       <li><a href=#before-attribute-name-state><span class=secno>12.2.4.34 </span>Before attribute name state</a></li>
       <li><a href=#attribute-name-state><span class=secno>12.2.4.35 </span>Attribute name state</a></li>
       <li><a href=#after-attribute-name-state><span class=secno>12.2.4.36 </span>After attribute name state</a></li>
       <li><a href=#before-attribute-value-state><span class=secno>12.2.4.37 </span>Before attribute value state</a></li>
       <li><a href=#attribute-value-(double-quoted)-state><span class=secno>12.2.4.38 </span>Attribute value (double-quoted) state</a></li>
       <li><a href=#attribute-value-(single-quoted)-state><span class=secno>12.2.4.39 </span>Attribute value (single-quoted) state</a></li>
       <li><a href=#attribute-value-(unquoted)-state><span class=secno>12.2.4.40 </span>Attribute value (unquoted) state</a></li>
       <li><a href=#character-reference-in-attribute-value-state><span class=secno>12.2.4.41 </span>Character reference in attribute value state</a></li>
       <li><a href=#after-attribute-value-(quoted)-state><span class=secno>12.2.4.42 </span>After attribute value (quoted) state</a></li>
       <li><a href=#self-closing-start-tag-state><span class=secno>12.2.4.43 </span>Self-closing start tag state</a></li>
       <li><a href=#bogus-comment-state><span class=secno>12.2.4.44 </span>Bogus comment state</a></li>
       <li><a href=#markup-declaration-open-state><span class=secno>12.2.4.45 </span>Markup declaration open state</a></li>
       <li><a href=#comment-start-state><span class=secno>12.2.4.46 </span>Comment start state</a></li>
       <li><a href=#comment-start-dash-state><span class=secno>12.2.4.47 </span>Comment start dash state</a></li>
       <li><a href=#comment-state><span class=secno>12.2.4.48 </span>Comment state</a></li>
       <li><a href=#comment-end-dash-state><span class=secno>12.2.4.49 </span>Comment end dash state</a></li>
       <li><a href=#comment-end-state><span class=secno>12.2.4.50 </span>Comment end state</a></li>
       <li><a href=#comment-end-bang-state><span class=secno>12.2.4.51 </span>Comment end bang state</a></li>
       <li><a href=#doctype-state><span class=secno>12.2.4.52 </span>DOCTYPE state</a></li>
       <li><a href=#before-doctype-name-state><span class=secno>12.2.4.53 </span>Before DOCTYPE name state</a></li>
       <li><a href=#doctype-name-state><span class=secno>12.2.4.54 </span>DOCTYPE name state</a></li>
       <li><a href=#after-doctype-name-state><span class=secno>12.2.4.55 </span>After DOCTYPE name state</a></li>
       <li><a href=#after-doctype-public-keyword-state><span class=secno>12.2.4.56 </span>After DOCTYPE public keyword state</a></li>
       <li><a href=#before-doctype-public-identifier-state><span class=secno>12.2.4.57 </span>Before DOCTYPE public identifier state</a></li>
       <li><a href=#doctype-public-identifier-(double-quoted)-state><span class=secno>12.2.4.58 </span>DOCTYPE public identifier (double-quoted) state</a></li>
       <li><a href=#doctype-public-identifier-(single-quoted)-state><span class=secno>12.2.4.59 </span>DOCTYPE public identifier (single-quoted) state</a></li>
       <li><a href=#after-doctype-public-identifier-state><span class=secno>12.2.4.60 </span>After DOCTYPE public identifier state</a></li>
       <li><a href=#between-doctype-public-and-system-identifiers-state><span class=secno>12.2.4.61 </span>Between DOCTYPE public and system identifiers state</a></li>
       <li><a href=#after-doctype-system-keyword-state><span class=secno>12.2.4.62 </span>After DOCTYPE system keyword state</a></li>
       <li><a href=#before-doctype-system-identifier-state><span class=secno>12.2.4.63 </span>Before DOCTYPE system identifier state</a></li>
       <li><a href=#doctype-system-identifier-(double-quoted)-state><span class=secno>12.2.4.64 </span>DOCTYPE system identifier (double-quoted) state</a></li>
       <li><a href=#doctype-system-identifier-(single-quoted)-state><span class=secno>12.2.4.65 </span>DOCTYPE system identifier (single-quoted) state</a></li>
       <li><a href=#after-doctype-system-identifier-state><span class=secno>12.2.4.66 </span>After DOCTYPE system identifier state</a></li>
       <li><a href=#bogus-doctype-state><span class=secno>12.2.4.67 </span>Bogus DOCTYPE state</a></li>
       <li><a href=#cdata-section-state><span class=secno>12.2.4.68 </span>CDATA section state</a></li>
       <li><a href=#tokenizing-character-references><span class=secno>12.2.4.69 </span>Tokenizing character references</a></ol></li>
     <li><a href=#tree-construction><span class=secno>12.2.5 </span>Tree construction</a>
      <ol>
       <li><a href=#creating-and-inserting-nodes><span class=secno>12.2.5.1 </span>Creating and inserting nodes</a></li>
       <li><a href=#parsing-elements-that-contain-only-text><span class=secno>12.2.5.2 </span>Parsing elements that contain only text</a></li>
       <li><a href=#closing-elements-that-have-implied-end-tags><span class=secno>12.2.5.3 </span>Closing elements that have implied end tags</a></li>
       <li><a href=#parsing-main-inhtml><span class=secno>12.2.5.4 </span>The rules for parsing tokens in HTML content</a>
        <ol>
         <li><a href=#the-initial-insertion-mode><span class=secno>12.2.5.4.1 </span>The "initial" insertion mode</a></li>
         <li><a href=#the-before-html-insertion-mode><span class=secno>12.2.5.4.2 </span>The "before html" insertion mode</a></li>
         <li><a href=#the-before-head-insertion-mode><span class=secno>12.2.5.4.3 </span>The "before head" insertion mode</a></li>
         <li><a href=#parsing-main-inhead><span class=secno>12.2.5.4.4 </span>The "in head" insertion mode</a></li>
         <li><a href=#parsing-main-inheadnoscript><span class=secno>12.2.5.4.5 </span>The "in head noscript" insertion mode</a></li>
         <li><a href=#the-after-head-insertion-mode><span class=secno>12.2.5.4.6 </span>The "after head" insertion mode</a></li>
         <li><a href=#parsing-main-inbody><span class=secno>12.2.5.4.7 </span>The "in body" insertion mode</a></li>
         <li><a href=#parsing-main-incdata><span class=secno>12.2.5.4.8 </span>The "text" insertion mode</a></li>
         <li><a href=#parsing-main-intable><span class=secno>12.2.5.4.9 </span>The "in table" insertion mode</a></li>
         <li><a href=#parsing-main-intabletext><span class=secno>12.2.5.4.10 </span>The "in table text" insertion mode</a></li>
         <li><a href=#parsing-main-incaption><span class=secno>12.2.5.4.11 </span>The "in caption" insertion mode</a></li>
         <li><a href=#parsing-main-incolgroup><span class=secno>12.2.5.4.12 </span>The "in column group" insertion mode</a></li>
         <li><a href=#parsing-main-intbody><span class=secno>12.2.5.4.13 </span>The "in table body" insertion mode</a></li>
         <li><a href=#parsing-main-intr><span class=secno>12.2.5.4.14 </span>The "in row" insertion mode</a></li>
         <li><a href=#parsing-main-intd><span class=secno>12.2.5.4.15 </span>The "in cell" insertion mode</a></li>
         <li><a href=#parsing-main-inselect><span class=secno>12.2.5.4.16 </span>The "in select" insertion mode</a></li>
         <li><a href=#parsing-main-inselectintable><span class=secno>12.2.5.4.17 </span>The "in select in table" insertion mode</a></li>
         <li><a href=#parsing-main-intemplate><span class=secno>12.2.5.4.18 </span>The "in template" insertion mode</a></li>
         <li><a href=#parsing-main-afterbody><span class=secno>12.2.5.4.19 </span>The "after body" insertion mode</a></li>
         <li><a href=#parsing-main-inframeset><span class=secno>12.2.5.4.20 </span>The "in frameset" insertion mode</a></li>
         <li><a href=#parsing-main-afterframeset><span class=secno>12.2.5.4.21 </span>The "after frameset" insertion mode</a></li>
         <li><a href=#the-after-after-body-insertion-mode><span class=secno>12.2.5.4.22 </span>The "after after body" insertion mode</a></li>
         <li><a href=#the-after-after-frameset-insertion-mode><span class=secno>12.2.5.4.23 </span>The "after after frameset" insertion mode</a></ol></li>
       <li><a href=#parsing-main-inforeign><span class=secno>12.2.5.5 </span>The rules for parsing tokens in foreign content</a></ol></li>
     <li><a href=#the-end><span class=secno>12.2.6 </span>The end</a></li>
     <li><a href=#coercing-an-html-dom-into-an-infoset><span class=secno>12.2.7 </span>Coercing an HTML DOM into an infoset</a></li>
     <li><a href=#an-introduction-to-error-handling-and-strange-cases-in-the-parser><span class=secno>12.2.8 </span>An introduction to error handling and strange cases in the parser</a>
      <ol>
       <li><a href=#misnested-tags:-b-i-/b-/i><span class=secno>12.2.8.1 </span>Misnested tags: &lt;b&gt;&lt;i&gt;&lt;/b&gt;&lt;/i&gt;</a></li>
       <li><a href=#misnested-tags:-b-p-/b-/p><span class=secno>12.2.8.2 </span>Misnested tags: &lt;b&gt;&lt;p&gt;&lt;/b&gt;&lt;/p&gt;</a></li>
       <li><a href=#unexpected-markup-in-tables><span class=secno>12.2.8.3 </span>Unexpected markup in tables</a></li>
       <li><a href=#scripts-that-modify-the-page-as-it-is-being-parsed><span class=secno>12.2.8.4 </span>Scripts that modify the page as it is being parsed</a></li>
       <li><a href=#the-execution-of-scripts-that-are-moving-across-multiple-documents><span class=secno>12.2.8.5 </span>The execution of scripts that are moving across multiple documents</a></li>
       <li><a href=#unclosed-formatting-elements><span class=secno>12.2.8.6 </span>Unclosed formatting elements</a></ol></ol></li>
   <li><a href=#serializing-html-fragments><span class=secno>12.3 </span>Serializing HTML fragments</a></li>
   <li><a href=#parsing-html-fragments><span class=secno>12.4 </span>Parsing HTML fragments</a></li>
   <li><a href=#named-character-references><span class=secno>12.5 </span>Named character references</a></ol></li>
 <li><a href=#the-xhtml-syntax><span class=secno>13 </span>The XHTML syntax</a>
  <ol>
   <li><a href=#writing-xhtml-documents><span class=secno>13.1 </span>Writing XHTML documents</a></li>
   <li><a href=#parsing-xhtml-documents><span class=secno>13.2 </span>Parsing XHTML documents</a></li>
   <li><a href=#serializing-xhtml-fragments><span class=secno>13.3 </span>Serializing XHTML fragments</a></li>
   <li><a href=#parsing-xhtml-fragments><span class=secno>13.4 </span>Parsing XHTML fragments</a></ol></li>
 <li><a href=#rendering><span class=secno>14 </span>Rendering</a>
  <ol>
   <li><a href=#introduction-13><span class=secno>14.1 </span>Introduction</a></li>
   <li><a href=#the-css-user-agent-style-sheet-and-presentational-hints><span class=secno>14.2 </span>The CSS user agent style sheet and presentational hints</a></li>
   <li><a href=#non-replaced-elements><span class=secno>14.3 </span>Non-replaced elements</a>
    <ol>
     <li><a href=#hidden-elements><span class=secno>14.3.1 </span>Hidden elements</a></li>
     <li><a href=#the-page><span class=secno>14.3.2 </span>The page</a></li>
     <li><a href=#flow-content-1><span class=secno>14.3.3 </span>Flow content</a></li>
     <li><a href=#phrasing-content-1><span class=secno>14.3.4 </span>Phrasing content</a></li>
     <li><a href=#bidirectional-text><span class=secno>14.3.5 </span>Bidirectional text</a></li>
     <li><a href=#quotes><span class=secno>14.3.6 </span>Quotes</a></li>
     <li><a href=#sections-and-headings><span class=secno>14.3.7 </span>Sections and headings</a></li>
     <li><a href=#lists><span class=secno>14.3.8 </span>Lists</a></li>
     <li><a href=#tables><span class=secno>14.3.9 </span>Tables</a></li>
     <li><a href=#margin-collapsing-quirks><span class=secno>14.3.10 </span>Margin collapsing quirks</a></li>
     <li><a href=#form-controls><span class=secno>14.3.11 </span>Form controls</a></li>
     <li><a href=#the-hr-element-0><span class=secno>14.3.12 </span>The <code>hr</code> element</a></li>
     <li><a href=#the-fieldset-and-legend-elements><span class=secno>14.3.13 </span>The <code>fieldset</code> and <code>legend</code> elements</a></ol></li>
   <li><a href=#replaced-elements><span class=secno>14.4 </span>Replaced elements</a>
    <ol>
     <li><a href=#embedded-content-2><span class=secno>14.4.1 </span>Embedded content</a></li>
     <li><a href=#images-0><span class=secno>14.4.2 </span>Images</a></li>
     <li><a href=#attributes-for-embedded-content-and-images><span class=secno>14.4.3 </span>Attributes for embedded content and images</a></li>
     <li><a href=#image-maps-0><span class=secno>14.4.4 </span>Image maps</a></ol></li>
   <li><a href=#bindings><span class=secno>14.5 </span>Bindings</a>
    <ol>
     <li><a href=#introduction-14><span class=secno>14.5.1 </span>Introduction</a></li>
     <li><a href=#the-button-element-0><span class=secno>14.5.2 </span>The <code>button</code> element</a></li>
     <li><a href=#the-details-element-0><span class=secno>14.5.3 </span>The <code>details</code> element</a></li>
     <li><a href=#the-input-element-as-a-text-entry-widget><span class=secno>14.5.4 </span>The <code>input</code> element as a text entry widget</a></li>
     <li><a href=#the-input-element-as-domain-specific-widgets><span class=secno>14.5.5 </span>The <code>input</code> element as domain-specific widgets</a></li>
     <li><a href=#the-input-element-as-a-range-control><span class=secno>14.5.6 </span>The <code>input</code> element as a range control</a></li>
     <li><a href=#the-input-element-as-a-color-well><span class=secno>14.5.7 </span>The <code>input</code> element as a color well</a></li>
     <li><a href=#the-input-element-as-a-checkbox-and-radio-button-widgets><span class=secno>14.5.8 </span>The <code>input</code> element as a checkbox and radio button widgets</a></li>
     <li><a href=#the-input-element-as-a-file-upload-control><span class=secno>14.5.9 </span>The <code>input</code> element as a file upload control</a></li>
     <li><a href=#the-input-element-as-a-button><span class=secno>14.5.10 </span>The <code>input</code> element as a button</a></li>
     <li><a href=#the-marquee-element-0><span class=secno>14.5.11 </span>The <code>marquee</code> element</a></li>
     <li><a href=#the-meter-element-0><span class=secno>14.5.12 </span>The <code>meter</code> element</a></li>
     <li><a href=#the-progress-element-0><span class=secno>14.5.13 </span>The <code>progress</code> element</a></li>
     <li><a href=#the-select-element-0><span class=secno>14.5.14 </span>The <code>select</code> element</a></li>
     <li><a href=#the-textarea-element-0><span class=secno>14.5.15 </span>The <code>textarea</code> element</a></li>
     <li><a href=#the-keygen-element-0><span class=secno>14.5.16 </span>The <code>keygen</code> element</a></ol></li>
   <li><a href=#frames-and-framesets><span class=secno>14.6 </span>Frames and framesets</a></li>
   <li><a href=#interactive-media><span class=secno>14.7 </span>Interactive media</a>
    <ol>
     <li><a href=#links,-forms,-and-navigation><span class=secno>14.7.1 </span>Links, forms, and navigation</a></li>
     <li><a href=#the-title-attribute-0><span class=secno>14.7.2 </span>The <code title=attr-title>title</code> attribute</a></li>
     <li><a href=#editing-hosts><span class=secno>14.7.3 </span>Editing hosts</a></li>
     <li><a href=#text-rendered-in-native-user-interfaces><span class=secno>14.7.4 </span>Text rendered in native user interfaces</a></ol></li>
   <li><a href=#print-media><span class=secno>14.8 </span>Print media</a></li>
   <li><a href=#unstyled-xml-documents><span class=secno>14.9 </span>Unstyled XML documents</a></ol></li>
 <li><a href=#obsolete><span class=secno>15 </span>Obsolete features</a>
  <ol>
   <li><a href=#obsolete-but-conforming-features><span class=secno>15.1 </span>Obsolete but conforming features</a>
    <ol>
     <li><a href=#warnings-for-obsolete-but-conforming-features><span class=secno>15.1.1 </span>Warnings for obsolete but conforming features</a></ol></li>
   <li><a href=#non-conforming-features><span class=secno>15.2 </span>Non-conforming features</a></li>
   <li><a href=#requirements-for-implementations><span class=secno>15.3 </span>Requirements for implementations</a>
    <ol>
     <li><a href=#the-applet-element><span class=secno>15.3.1 </span>The <code>applet</code> element</a></li>
     <li><a href=#the-marquee-element><span class=secno>15.3.2 </span>The <code>marquee</code> element</a></li>
     <li><a href=#frames><span class=secno>15.3.3 </span>Frames</a></li>
     <li><a href=#other-elements,-attributes-and-apis><span class=secno>15.3.4 </span>Other elements, attributes and APIs</a></ol></ol></li>
 <li><a href=#iana><span class=secno>16 </span>IANA considerations</a>
  <ol>
   <li><a href=#text/html><span class=secno>16.1 </span><code>text/html</code></a></li>
   <li><a href=#multipart/x-mixed-replace><span class=secno>16.2 </span><code>multipart/x-mixed-replace</code></a></li>
   <li><a href=#application/xhtml+xml><span class=secno>16.3 </span><code>application/xhtml+xml</code></a></li>
   <li><a href=#application/x-www-form-urlencoded><span class=secno>16.4 </span><code>application/x-www-form-urlencoded</code></a></li>
   <li><a href=#text/cache-manifest><span class=secno>16.5 </span><code>text/cache-manifest</code></a></li>
   <li><a href=#text/ping><span class=secno>16.6 </span><code>text/ping</code></a></li>
   <li><a href=#application/microdata+json><span class=secno>16.7 </span><code>application/microdata+json</code></a></li>
   <li><a href=#ping-from><span class=secno>16.8 </span><code>Ping-From</code></a></li>
   <li><a href=#ping-to><span class=secno>16.9 </span><code>Ping-To</code></a></li>
   <li><a href=#web+-scheme-prefix><span class=secno>16.10 </span><code>web+</code> scheme prefix</a></ol></li>
 <li><a href=#index class=no-num>Index</a>
  <ol>
   <li><a href=#elements-1 class=no-num>Elements</a></li>
   <li><a href=#element-content-categories class=no-num>Element content categories</a></li>
   <li><a href=#attributes-1 class=no-num>Attributes</a></li>
   <li><a href=#element-interfaces class=no-num>Element Interfaces</a></li>
   <li><a href=#all-interfaces class=no-num>All Interfaces</a></ol></li>
 <li><a href=#references class=no-num>References</a></li>
 <li><a href=#acknowledgments class=no-num>Acknowledgments</a></ol>
<!--end-toc-->
  <hr><h2 id=introduction><span class=secno>1 </span>Introduction</h2>


  <h3 id=abstract><span class=secno>1.1 </span>Where does this specification fit?</h3>

  <p>This specification defines a big part of the Web platform, in
  lots of detail. Its place in the Web platform specification stack
  relative to other specifications can be best summed up as
  follows:</p>

1765
  <p><img src=greenbox.png width=398 alt="It consists of everything else, above such core technologies as HTTP, URI/IRIs, DOM, XML, Unicode, and ECMAScript; below presentation-layer technologies like CSS, XBL, and the NPAPI; and to the side of technologies like Geolocation, SVG, MathML, and XHR." height=359></p>
1766 1767 1768 1769 1770 1771 1772 1773 1774 1775 1776 1777 1778 1779 1780 1781 1782 1783 1784 1785 1786 1787 1788 1789 1790 1791 1792 1793 1794 1795 1796 1797 1798 1799 1800 1801 1802 1803 1804 1805 1806 1807 1808 1809 1810 1811 1812 1813 1814 1815 1816 1817 1818 1819 1820 1821 1822 1823 1824 1825 1826 1827 1828 1829 1830 1831 1832 1833 1834 1835 1836 1837 1838 1839 1840 1841 1842 1843 1844 1845 1846 1847 1848 1849 1850 1851 1852 1853 1854 1855 1856 1857 1858 1859 1860 1861 1862 1863 1864 1865 1866 1867 1868 1869 1870 1871 1872 1873 1874 1875 1876 1877 1878 1879 1880 1881 1882 1883 1884 1885 1886 1887 1888 1889 1890 1891 1892 1893 1894 1895 1896 1897 1898 1899 1900 1901 1902 1903 1904 1905 1906 1907 1908 1909 1910 1911 1912 1913 1914 1915 1916 1917 1918 1919 1920 1921 1922 1923 1924 1925 1926 1927 1928 1929 1930 1931 1932 1933 1934 1935 1936 1937 1938 1939 1940 1941 1942 1943 1944 1945 1946 1947 1948 1949 1950 1951 1952 1953 1954 1955 1956 1957 1958 1959 1960 1961 1962 1963 1964 1965 1966 1967 1968 1969 1970 1971 1972 1973 1974 1975 1976 1977 1978 1979 1980 1981 1982 1983 1984 1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018 2019 2020 2021 2022 2023 2024 2025 2026 2027 2028 2029 2030 2031 2032 2033 2034 2035 2036 2037 2038 2039 2040 2041 2042 2043 2044 2045 2046 2047 2048 2049 2050 2051 2052 2053 2054 2055 2056 2057 2058 2059 2060 2061 2062 2063 2064 2065 2066 2067 2068 2069 2070 2071 2072 2073 2074 2075 2076 2077 2078 2079 2080 2081 2082 2083 2084 2085 2086 2087 2088 2089 2090 2091 2092 2093 2094 2095 2096 2097 2098 2099 2100 2101 2102 2103 2104 2105 2106 2107 2108 2109 2110 2111 2112 2113 2114 2115 2116 2117 2118 2119 2120 2121 2122 2123 2124 2125 2126 2127 2128 2129 2130 2131 2132 2133 2134 2135 2136 2137 2138 2139 2140 2141 2142 2143 2144 2145 2146 2147 2148 2149 2150 2151 2152 2153 2154 2155 2156 2157 2158 2159 2160 2161 2162 2163 2164 2165 2166 2167 2168 2169 2170 2171 2172 2173 2174 2175 2176 2177 2178 2179 2180 2181 2182 2183 2184 2185 2186 2187 2188 2189 2190 2191 2192 2193 2194 2195 2196 2197 2198 2199 2200 2201 2202 2203 2204 2205 2206 2207 2208 2209 2210 2211 2212 2213 2214 2215 2216 2217 2218 2219 2220 2221 2222 2223 2224 2225 2226 2227 2228 2229 2230 2231 2232 2233 2234 2235 2236 2237 2238 2239 2240 2241 2242 2243 2244 2245 2246 2247 2248 2249 2250 2251 2252 2253 2254 2255 2256 2257 2258 2259 2260 2261 2262 2263 2264 2265 2266 2267 2268 2269 2270 2271 2272 2273 2274 2275 2276 2277 2278 2279 2280 2281 2282 2283 2284 2285 2286 2287 2288 2289 2290 2291 2292 2293 2294



  <h3 id=is-this-html5?><span class=secno>1.2 </span>Is this HTML5?</h3><!--VERSION-->

  <p><i>This section is non-normative.</i></p>

  <p>In short: Yes.</p>

  <p>In more length: The term "HTML5" is widely used as a buzzword to
  refer to modern Web technologies, many of which (though by no means
  all) are developed at the WHATWG, in some cases in conjunction with
  the W3C and IETF.</p>

  <p>The WHATWG work is all published in one specification

  (the one you are reading right now),
  parts of which are republished in an edition optimized for Web developers.

  </p>

  <p>The W3C also publishes parts of this specification as separate
  documents. One of these parts is called "HTML5"; it is a forked subset of

  this specification (the HTML Living Standard).
  There are numerous differences between 

  this specification (the HTML Living Standard)
  and the W3C version, some minor, some major. Unfortunately these are not currently accurately
  documented anywhere, so there is no way to know which are intentional and which are not.</p>



  <h3 id=background><span class=secno>1.3 </span>Background</h3>

  <p><i>This section is non-normative.</i></p>

  <p>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.</p>

  <p>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.</p>


  <h3 id=audience><span class=secno>1.4 </span>Audience</h3>

  <p><i>This section is non-normative.</i></p>

  <p>This specification is intended for authors of documents and scripts that use the features
  defined in this specification<span class=impl>, 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</span>.</p>

  <p>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.</p>

  <p>In particular, familiarity with the basics of DOM 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.</p>


  <h3 id=scope><span class=secno>1.5 </span>Scope</h3>

  <p><i>This section is non-normative.</i></p>

  <p>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.</p>

  <p>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).</p>

  <p>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. Examples of such applications include 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.</p>


  <h3 id=history-1><span class=secno>1.6 </span>History</h3>

  <p><i>This section is non-normative.</i></p>

  <p>For its first five years (1990-1995), HTML went through a number of revisions and experienced a
  number of extensions, primarily hosted first at CERN, and then at the IETF.</p>

  <p>With the creation of the W3C, HTML's development changed venue again. A first abortive attempt
  at extending HTML in 1995 known as HTML 3.0 then made way to a more pragmatic approach known as
  HTML 3.2, which was completed in 1997. HTML4 quickly followed later that same year.</p>

  <p>The following year, the W3C membership decided to stop evolving HTML and instead begin work on
  an XML-based equivalent, called XHTML. <!-- http://www.w3.org/MarkUp/future/#summary --> This
  effort started with a reformulation of HTML4 in XML, known as XHTML 1.0, which added no new
  features except the new serialization, and which was completed in 2000. After XHTML 1.0, the W3C's
  focus turned to making it easier for other working groups to extend XHTML, under the banner of
  XHTML Modularization. In parallel with this, the W3C also worked on a new language that was not
  compatible with the earlier HTML and XHTML languages, calling it XHTML2.</p>

  <p>Around the time that HTML's evolution was stopped in 1998, parts of the API for HTML developed
  by browser vendors were specified and published under the name DOM Level 1 (in 1998) and DOM Level
  2 Core and DOM Level 2 HTML (starting in 2000 and culminating in 2003). These efforts then petered
  out, with some DOM Level 3 specifications published in 2004 but the working group being closed
  before all the Level 3 drafts were completed.</p>

  <p>In 2003, the publication of XForms, a technology which was positioned as the next generation of
  Web forms, sparked a renewed interest in evolving HTML itself, rather than finding replacements
  for it. This interest was borne from the realization that XML's deployment as a Web technology was
  limited to entirely new technologies (like RSS and later Atom), rather than as a replacement for
  existing deployed technologies (like HTML).</p>

  <p>A proof of concept to show that it was possible to extend HTML4'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, was the first result of this renewed
  interest. 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.</p>

  <p>The idea that HTML's evolution should be reopened was tested at a W3C workshop in 2004, where
  some of the principles that underlie the HTML5 work (described below), as well as the
  aforementioned early draft proposal covering just forms-related features, were presented to the
  W3C jointly by Mozilla and Opera. The proposal was rejected on the grounds that the proposal
  conflicted with the previously chosen direction for the Web's evolution; the W3C staff and
  membership voted to continue developing XML-based replacements instead.</p>

  <p>Shortly thereafter, Apple, Mozilla, and Opera jointly announced their intent to continue
  working on the effort under the umbrella of a new venue called the WHATWG. A public mailing list
  was created, and the draft was moved to the WHATWG site. The copyright was subsequently amended to
  be jointly owned by all three vendors, and to allow reuse of the specification.</p>

  <p>The WHATWG was based on several core principles, in particular that technologies need to be
  backwards compatible, that specifications and implementations need to match even if this means
  changing the specification rather than the implementations, and that specifications need to be
  detailed enough that implementations can achieve complete interoperability without
  reverse-engineering each other.</p>

  <p>The latter requirement in particular required that the scope of the HTML5 specification include
  what had previously been specified in three separate documents: HTML4, XHTML1, and DOM2 HTML. It
  also meant including significantly more detail than had previously been considered the norm.</p>

  <p>In 2006, the W3C indicated an interest to participate in the development of HTML5 after all,
  and in 2007 formed a working group chartered to work with the WHATWG on the development of the
  HTML5 specification. Apple, Mozilla, and Opera allowed the W3C to publish the specification under
  the W3C copyright, while keeping a version with the less restrictive license on the WHATWG
  site.</p>

  <p>For a number of years, both groups then worked together. In 2011, however, the groups came to
  the conclusion that they had different goals: the W3C wanted to publish a "finished" version of
  "HTML5", while the WHATWG wanted to continue working on a Living Standard for HTML, continuously
  maintaining the specification rather than freezing it in a state with known problems, and adding
  new features as needed to evolve the platform.</p>

  <p>Since then, the WHATWG has been working on this specification (amongst others), and the W3C has
  been copying fixes made by the WHATWG into their fork of the document, as well as making other
  changes, some intentional and some not, with no documentation listing or explaining the
  differences.</p>




  <h3 id=design-notes><span class=secno>1.7 </span>Design notes</h3>

  <p><i>This section is non-normative.</i></p>

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

  <p>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.</p>

  <p>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.</p>

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


  <h4 id=serializability-of-script-execution><span class=secno>1.7.1 </span>Serializability of script execution</h4>

  <p><i>This section is non-normative.</i></p>

  <p>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 <a href=#worker title=Worker>workers</a>, the intent is that the behavior of implementations can
  be thought of as completely serializing the execution of all scripts in all <a href=#browsing-context title="browsing
  context">browsing contexts</a>.</p>

  <p class=note>The <code title=dom-navigator-yieldForStorageUpdates><a href=#dom-navigator-yieldforstorageupdates>navigator.yieldForStorageUpdates()</a></code> method, in
  this model, is equivalent to allowing other scripts to run while the calling script is
  blocked.</p>


  <h4 id=compliance-with-other-specifications><span class=secno>1.7.2 </span>Compliance with other specifications</h4>

  <p><i>This section is non-normative.</i></p>

  <p>This specification interacts with and relies on a wide variety of other specifications. In
  certain circumstances, unfortunately, conflicting needs have led to this specification violating
  the requirements of these other specifications. Whenever this has occurred, the transgressions
  have each been noted as a "<dfn id=willful-violation>willful violation</dfn>", and the reason for the violation has
  been noted.</p>


  <h4 id=extensibility><span class=secno>1.7.3 </span>Extensibility</h4>

  <p><i>This section is non-normative.</i></p>

  <p>HTML has a wide number of extensibility mechanisms that can be used for adding semantics in a
  safe manner:</p>

  <ul><li>Authors can use the <code title=attr-class><a href=#classes>class</a></code> attribute to extend elements,
   effectively creating their own elements, while using the most applicable existing "real" HTML
   element, so that browsers and other tools that don't know of the extension can still support it
   somewhat well. This is the tack used by microformats, for example.</li>

   <li>Authors can include data for inline client-side scripts or server-side site-wide scripts to
   process using the <code title=attr-data-*><a href=#attr-data-*>data-*=""</a></code> attributes. These are guaranteed to
   never be touched by browsers, and allow scripts to include data on HTML elements that scripts can
   then look for and process.</li>

   <li>Authors can use the <code title=meta><a href=#the-meta-element>&lt;meta name="" content=""&gt;</a></code> mechanism to
   include page-wide metadata by registering <a href=#concept-meta-extensions title=concept-meta-extensions>extensions to the
   predefined set of metadata names</a>.</li>

   <li>Authors can use the <code title=attr-hyperlink-rel><a href=#attr-hyperlink-rel>rel=""</a></code> mechanism to annotate
   links with specific meanings by registering <a href=#concept-rel-extensions title=concept-rel-extensions>extensions to
   the predefined set of link types</a>. This is also used by microformats.</li>

   <li>Authors can embed raw data using the <code title=script><a href=#the-script-element>&lt;script type=""&gt;</a></code>
   mechanism with a custom type, for further handling by inline or server-side scripts.</li>

   <li>Authors can create <a href=#plugin title=plugin>plugins</a> and invoke them using the
   <code><a href=#the-embed-element>embed</a></code> element. This is how Flash works.</li>

   <li>Authors can extend APIs using the JavaScript prototyping mechanism. This is widely used by
   script libraries, for instance.</li>

   <li>Authors can use the microdata feature (the <code title=attr-itemscope><a href=#attr-itemscope>itemscope=""</a></code>
   and <code title=attr-itemprop><a href=#names:-the-itemprop-attribute>itemprop=""</a></code> attributes) to embed nested name-value pairs
   of data to be shared with other applications and sites.</li>

  </ul><h3 id=html-vs-xhtml><span class=secno>1.8 </span>HTML vs XHTML</h3>

  <p><i>This section is non-normative.</i></p>

  <p>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.</p>

  <p>The in-memory representation is known as "DOM HTML", or "the DOM" for short.</p>

  <p>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.</p>

  <p>The first such concrete syntax is the HTML syntax. This is the format suggested for most
  authors. It is compatible with most legacy Web browsers. If a document is transmitted with the
  <code><a href=#text/html>text/html</a></code> <a href=#mime-type>MIME type</a>, then it will be processed as an HTML document by
  Web browsers. This specification defines the latest HTML syntax, known simply as "HTML".</p>

  <p>The second concrete syntax is the XHTML syntax, which is an application of XML. When a document
  is transmitted with an <a href=#xml-mime-type>XML MIME type</a>, such as <code><a href=#application/xhtml+xml>application/xhtml+xml</a></code>,
  then it is treated as an XML document by Web browsers, to be parsed by an XML processor. Authors
  are reminded that the processing for XML and HTML differs; in particular, even minor syntax errors
  will prevent a document labeled as XML from being rendered fully, whereas they would be ignored in
  the HTML syntax. This specification defines the latest XHTML syntax, known simply as "XHTML".</p>

  <p>The DOM, the HTML syntax, and the XHTML syntax cannot all represent the same content. For
  example, namespaces cannot be represented using the HTML syntax, but they are supported in the DOM
  and in the XHTML syntax. Similarly, documents that use the <code><a href=#the-noscript-element>noscript</a></code> feature can be
  represented using the HTML syntax, but cannot be represented with the DOM or in the XHTML syntax.
  Comments that contain the string "<code title="">--&gt;</code>" can only be represented in the
  DOM, not in the HTML and XHTML syntaxes.</p>


  <h3 id=structure-of-this-specification><span class=secno>1.9 </span>Structure of this specification</h3>

  <p><i>This section is non-normative.</i></p>

  <p>This specification is divided into the following major sections:</p>

  <dl><dt><a href=#introduction>Introduction</a></dt>

   <dd>Non-normative materials providing a context for the HTML standard.</dd>


   <dt><a href=#infrastructure>Common infrastructure</a></dt>

   <dd>The conformance classes, algorithms, definitions, and the common underpinnings of the rest of
   the specification.</dd>


   <dt><a href=#dom>Semantics, structure, and APIs of HTML documents</a></dt>

   <dd>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.</dd>


   <dt><a href=#semantics>The elements of HTML</a></dt>

   <dd>Each element has a predefined meaning, which is explained in this section. Rules for authors
   on how to use the element<span class=impl>, along with user agent requirements for how to
   handle each element,</span> are also given. This includes large signature features of HTML such
   as video playback and subtitles, form controls and form submission, and a 2D graphics API known
   as the HTML canvas.</dd>


   <dt><a href=#microdata>Microdata</a></dt>

   <dd>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<span class=impl> and some algorithms that can be used to convert HTML
   documents into other formats</span>. This section also defines some sample Microdata vocabularies
   for contact information, calendar events, and licensing works.</dd>


   <dt><a href=#browsers>Loading Web pages</a></dt>

   <dd>HTML documents do not exist in a vacuum &mdash; this section defines many of the features
   that affect environments that deal with multiple pages, such as Web browsers and offline
   caching of Web applications.</dd>


   <dt><a href=#webappapis>Web application APIs</a></dt>

   <dd>This section introduces basic features for scripting of applications in HTML.</dd>


   <dt><a href=#editing>User interaction</a></dt>

   <dd>HTML documents can provide a number of mechanisms for users to interact with and modify
   content, which are described in this section, such as how focus works, and drag-and-drop.</dd>


   <dt><a href=#workers>Web workers</a></dt>

   <dd>This section defines an API for background threads in JavaScript.</dd>


   <dt><a href=#comms>The communication APIs</a></dt>

   <dd>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. It also
   introduces a server-push event stream mechanism known as Server Sent Events or
   <code><a href=#eventsource>EventSource</a></code>, and a two-way full-duplex socket protocol for scripts known as Web
   Sockets.

   </dd>


   <dt><a href=#webstorage>Web storage</a></dt>

   <dd>This section defines a client-side storage mechanism based on name-value pairs.</dd>


   <dt><a href=#syntax>The HTML syntax</a></dt>
   <dt><a href=#xhtml>The XHTML syntax</a></dt>

   <dd>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 and XHTML<span class=impl>, along with rules for how to parse content using those syntaxes</span>.</dd>


   <dt><a href=#rendering>Rendering</a></dt>

   <dd>This section defines the default rendering rules for Web browsers.</dd>


  </dl><p>There are also some appendices, listing <a href=#obsolete>obsolete features</a> and <a href=#iana>IANA considerations</a>, and several indices.</p>



  <h4 id=how-to-read-this-specification><span class=secno>1.9.1 </span>How to read this specification</h4>

  <p>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.</p>

  <p>As described in the conformance requirements section below, this specification describes
  conformance criteria for a variety of conformance classes. In particular, there are conformance
  requirements that apply to <em>producers</em>, for example authors and the documents they create,
  and there are conformance requirements that apply to <em>consumers</em>, for example Web browsers.
  They can be distinguished by what they are requiring: a requirement on a producer states what is
  allowed, while a requirement on a consumer states how software is to act.</p>

  <div class=example>

   <p>For example, "the <code title="">foo</code> attribute's value must be a <a href=#valid-integer>valid
   integer</a>" is a requirement on producers, as it lays out the allowed values; in contrast,
   the requirement "the <code title="">foo</code> attribute's value must be parsed using the
   <a href=#rules-for-parsing-integers>rules for parsing integers</a>" is a requirement on consumers, as it describes how to
   process the content.</p>

  </div>

  <p><strong>Requirements on producers have no bearing whatsoever on consumers.</strong></p>

  <div class=example>

   <p>Continuing the above example, a requirement stating that a particular attribute's value is
   constrained to being a <a href=#valid-integer>valid integer</a> emphatically does <em>not</em> imply anything
   about the requirements on consumers. It might be that the consumers are in fact required to treat
   the attribute as an opaque string, completely unaffected by whether the value conforms to the
   requirements or not. It might be (as in the previous example) that the consumers are required to
   parse the value using specific rules that define how invalid (non-numeric in this case) values
   are to be processed.</p>

  </div>



  <h4 id=typographic-conventions><span class=secno>1.9.2 </span>Typographic conventions</h4>

  <p>This is a definition, requirement, or explanation.</p>

  <p class=note>This is a note.</p>

  <p class=example>This is an example.</p>

  <p class=XXX>This is an open issue.</p>

  <p class=warning>This is a warning.</p>

  <pre class="idl extract">interface <dfn title="">Example</dfn> {
  // this is an IDL definition
};</pre>

  <dl class=domintro><dt><var title="">variable</var> = <var title="">object</var> . <code title="">method</code>( [ <var title="">optionalArgument</var> ] )</dt>

   <dd>

    <p>This is a note to authors describing the usage of an interface.</p>

   </dd>

  </dl><pre class=css>/* this is a CSS fragment */</pre>

  <p>The defining instance of a term is marked up like <dfn id=x-this title=x-this>this</dfn>. Uses of that
  term are marked up like <a href=#x-this title=x-this>this</a> or like <i title=x-this><a href=#x-this>this</a></i>.</p>

  <p>The defining instance of an element, attribute, or API is marked up like <dfn id=x-that title=x-that><code>this</code></dfn>. References to that element, attribute, or API are marked
  up like <code title=x-that><a href=#x-that>this</a></code>.</p>

  <p>Other code fragments are marked up <code title="">like this</code>.</p>

  <p>Variables are marked up like <var title="">this</var>.</p>

  <!--<p class="impl">This is an implementation requirement.</p>-->

  <p>In an algorithm, steps in <a href=#synchronous-section title="synchronous section">synchronous sections</a> are
  marked with &#x231b;.</p>

  <p>In some cases, requirements are given in the form of lists with conditions and corresponding
  requirements. In such cases, the requirements that apply to a condition are always the first set
  of requirements that follow the condition, even in the case of there being multiple sets of
  conditions for those requirements. Such cases are presented as follows:</p>

  <dl class=switch><dt>This is a condition
   <dt>This is another condition
   </dt><dd>This is the requirement that applies to the conditions above.

   <dt>This is a third condition
   <dd>This is the requirement that applies to the third condition.

  </dl><h3 id=fingerprint><span class=secno>1.10 </span>Privacy concerns</h3>

  <p><i>This section is non-normative.</i></p>

  <p>Some features of HTML trade user convenience for a measure of user privacy.</p>

  <p>In general, due to the Internet's architecture, a user can be distinguished from another by the
  user's IP address. IP addresses do not perfectly match to a user; as a user moves from device to
  device, or from network to network, their IP address will change; similarly, NAT routing, proxy
  servers, and shared computers enable packets that appear to all come from a single IP address to
  actually map to multiple users. Technologies such as onion routing can be used to further
  anonymize requests so that requests from a single user at one node on the Internet appear to come
  from many disparate parts of the network.</p>

  <p>However, the IP address used for a user's requests is not the only mechanism by which a user's
  requests could be related to each other. Cookies, for example, are designed specifically to enable
  this, and are the basis of most of the Web's session features that enable you to log into a site
  with which you have an account.</p>

  <p>There are other mechanisms that are more subtle. Certain characteristics of a user's system can
  be used to distinguish groups of users from each other; by collecting enough such information, an
  individual user's browser's "digital fingerprint" can be computed, which can be as good, if not
  better, as an IP address in ascertaining which requests are from the same user.</p>

  <p>Grouping requests in this manner, especially across multiple sites, can be used for both benign
  (and even arguably positive) purposes, as well as for malevolent purposes. An example of a
  reasonably benign purpose would be determining whether a particular person seems to prefer sites
  with dog illustrations as opposed to sites with cat illustrations (based on how often they visit
  the sites in question) and then automatically using the preferred illustrations on subsequent
  visits to participating sites. Malevolent purposes, however, could include governments combining
  information such as the person's home address (determined from the addresses they use when getting
  driving directions on one site) with their apparent political affiliations (determined by
  examining the forum sites that they participate in) to determine whether the person should be
  prevented from voting in an election.</p>

  <p>Since the malevolent purposes can be remarkably evil, user agent implementors are encouraged to
  consider how to provide their users with tools to minimize leaking information that could be used
  to fingerprint a user.</p>

  <p>Unfortunately, as the first paragraph in this section implies, sometimes there is great benefit
  to be derived from exposing the very information that can also be used for fingerprinting
  purposes, so it's not as easy as simply blocking all possible leaks. For instance, the ability to
  log into a site to post under a specific identity requires that the user's requests be
  identifiable as all being from the same user, more or less by definition. More subtly, though,
  information such as how wide text is, which is necessary for many effects that involve drawing
  text onto a canvas (e.g. any effect that involves drawing a border around the text) also leaks
  information that can be used to group a user's requests. (In this case, by potentially exposing,
  via a brute force search, which fonts a user has installed, information which can vary
  considerably from user to user.)</p>

  <p>Features in this specification which can be <dfn id=fingerprinting-vector title="fingerprinting vector">used to
  fingerprint the user</dfn> are marked as this paragraph is.
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  <a href=#fingerprinting-vector class=fingerprint title="fingerprinting vector"><img src=greenbox.png width=46 alt="(This is a fingerprinting vector.)" height=64></a>
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