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<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01//EN">
<html lang=en-US>
<head>
<title>CSSOM</title>
<style type="text/css">
pre.idl { border:solid thin; background:#eee; color:#000; padding:0.5em }
pre.idl :link, pre.idl :visited { color:inherit; background:transparent }
dfn { font-weight:bold; font-style:normal }
div.example { margin-left:1em; padding-left:1em; border-left:double; color:#222; background:#fcfcfc }
div.example table code { color:inherit }
td, th { padding:.1em }
.note { margin-left:2em; color:green; font-style:italic; font-weight:bold }
p.note::before { content:"Note: " }
.XXX { padding:.5em; border:solid red }
p.XXX::before { content:"Issue: " }
em.ct { text-transform:lowercase; font-variant:small-caps; font-style:normal }
code { color:orangered }
code :link, code :visited { color:inherit }
</style>
<link href="http://www.w3.org/StyleSheets/TR/W3C-ED" rel=stylesheet>
<body class=draft>
<div class=head>
<h1 id=cssom>CSSOM</h1>
<h2 class="no-num no-toc" id="">Editor's Draft 16 October 2009</h2>
<dl>
<dt>This Version:
<dd><a
href="http://www.w3.org/TR/2009/ED-cssom-20091016/">http://www.w3.org/TR/2009/ED-cssom-20091016/</a>
<dt>Latest Version:
<dd><a href="http://www.w3.org/TR/cssom/">http://www.w3.org/TR/cssom/</a>
<dt>Latest Editor's draft:
<dd><a
href="http://dev.w3.org/csswg/cssom/">http://dev.w3.org/csswg/cssom/</a>
<dt>Previous Version:
<dd><a
href="http://www.w3.org/TR/2000/REC-DOM-Level-2-Style-20001113/">http://www.w3.org/TR/2000/REC-DOM-Level-2-Style-20001113/</a>
<dt>Editor:
<dd><a href="http://annevankesteren.nl/">Anne van Kesteren</a> (<a
href="http://www.opera.com/">Opera Software ASA</a>) <<a
href="mailto:annevk@opera.com">annevk@opera.com</a>>
</dl>
</div>
<h2 class="no-num no-toc" id=abstract>Abstract</h2>
<p>CSSOM defines how style sheets interact with the DOM and defines an API
for CSS style sheets.
<h2 class="no-num no-toc" id=sotd>Status of this Document</h2>
<p class=XXX>The plan is that this document provides the successor to DOM
Level 2 Style.</p>
<!--begin-status-->
<p>This is a public copy of the editors' draft. It is provided for
discussion only and may change at any moment. It probably contains errors.
Its publication here does not imply endorsement of its contents by W3C.
<!--end-status-->
<h2 class="no-num no-toc" id=toc>Table of Contents</h2>
<!--begin-toc-->
<ul class=toc>
<li><a href="#introduction"><span class=secno>1 </span>Introduction</a>
<ul class=toc>
<li><a href="#history"><span class=secno>1.1 </span>History</a>
</ul>
<li><a href="#conformance"><span class=secno>2 </span>Conformance
Requirements</a>
<li><a href="#terminology"><span class=secno>3 </span>Terminology</a>
<li><a href="#media-queries"><span class=secno>4 </span>Media Queries</a>
<ul class=toc>
<li><a href="#parsing-media-queries"><span class=secno>4.1
</span>Parsing Media Queries</a>
<li><a href="#serializing-media-queries"><span class=secno>4.2
</span>Serializing Media Queries</a>
<ul class=toc>
<li><a href="#serializing-media-feature-values"><span
class=secno>4.2.1 </span>Serializing Media Feature Values</a>
</ul>
<li><a href="#comparing-media-queries"><span class=secno>4.3
</span>Comparing Media Queries</a>
<li><a href="#the-medialist-interface"><span class=secno>4.4 </span>The
<code title="">MediaList</code> Interface</a>
<li><a href="#creating-a-medialist-object"><span class=secno>4.5
</span>Creating a <code title="">MediaList</code> Object</a>
</ul>
<li><a href="#selectors"><span class=secno>5 </span>Selectors</a>
<li><a href="#style-sheets"><span class=secno>6 </span>Style Sheets</a>
<ul class=toc>
<li><a href="#style-sheet0"><span class=secno>6.1 </span>Style Sheet</a>
<ul class=toc>
<li><a href="#the-stylesheet-interface"><span class=secno>6.1.1
</span>The <code title="">StyleSheet</code> Interface</a>
</ul>
<li><a href="#style-sheet-collections"><span class=secno>6.2
</span>Style Sheet Collections</a>
<ul class=toc>
<li><a href="#the-http-default-style-header"><span class=secno>6.2.1
</span>The HTTP <code title="">Default-Style</code> Header</a>
<li><a href="#the-stylesheetlist-sequence"><span class=secno>6.2.2
</span>The <code title="">StyleSheetList</code> Sequence</a>
<li><a href="#the-documentstyle-interface"><span class=secno>6.2.3
</span>The <code title="">DocumentStyle</code> Interface</a>
<li><a href="#interaction-with-the-user-interface"><span
class=secno>6.2.4 </span>Interaction with the User Interface</a>
<ul class=toc>
<li><a href="#persisting-the-selected-style-sheet-set"><span
class=secno>6.2.4.1. </span>Persisting the selected style sheet
set</a>
</ul>
<li><a href="#examples"><span class=secno>6.2.5 </span>Examples</a>
</ul>
<li><a href="#style-sheet-association"><span class=secno>6.3
</span>Style Sheet Association</a>
<ul class=toc>
<li><a href="#the-linkstyle-interface"><span class=secno>6.3.1
</span>The <code title="">LinkStyle</code> Interface</a>
<li><a href="#requirements-on-specifications"><span class=secno>6.3.2
</span>Requirements on specifications</a>
<li><a href="#requirements-on-user-agents-implementing"><span
class=secno>6.3.3 </span>Requirements on User Agents Implementing the
<span title=""><code>xml-stylesheet</code> processing
instruction</span></a>
<li><a href="#requirements-on-user-agents-implementing0"><span
class=secno>6.3.4 </span>Requirements on User Agents Implementing the
HTTP <code title="">Link</code> Header</a>
</ul>
</ul>
<li><a href="#css-style-sheets"><span class=secno>7 </span>CSS Style
Sheets</a>
<ul class=toc>
<li><a href="#css-style-sheet"><span class=secno>7.1 </span>CSS Style
Sheet</a>
<ul class=toc>
<li><a href="#the-cssstylesheet-interface"><span class=secno>7.1.1
</span>The <code title="">CSSStyleSheet</code> Interface</a>
</ul>
<li><a href="#css-statements"><span class=secno>7.2 </span>CSS
Statements</a>
<ul class=toc>
<li><a href="#the-cssrulelist-interface"><span class=secno>7.2.1
</span>The <code title="">CSSRuleList</code> Interface</a>
<li><a href="#the-cssrule-interface"><span class=secno>7.2.2
</span>The <code title="">CSSRule</code> Interface</a>
<ul class=toc>
<li><a href="#extensibility"><span class=secno>7.2.2.1.
</span>Extensibility</a>
</ul>
<li><a href="#the-cssstylerule-interface"><span class=secno>7.2.3
</span>The <code title="">CSSStyleRule</code> Interface</a>
<li><a href="#the-cssimportrule-interface"><span class=secno>7.2.4
</span>The <code title="">CSSImportRule</code> Interface</a>
<li><a href="#the-cssmediarule-interface"><span class=secno>7.2.5
</span>The <code title="">CSSMediaRule</code> Interface</a>
<li><a href="#the-cssfontfacerule-interface"><span class=secno>7.2.6
</span>The <code title="">CSSFontFaceRule</code> Interface</a>
<li><a href="#the-csspagerule-interface"><span class=secno>7.2.7
</span>The <code title="">CSSPageRule</code> Interface</a>
<li><a href="#the-cssnamespacerule-interface"><span class=secno>7.2.8
</span>The <code title="">CSSNamespaceRule</code> Interface</a>
</ul>
<li><a href="#css-declaration-blocks"><span class=secno>7.3 </span>CSS
Declaration Blocks</a>
<ul class=toc>
<li><a href="#examples-of-the-css-value-serializing-al"><span
class=secno>7.3.1 </span>Examples of the CSS Value Serializing
Algorithm</a>
<li><a href="#the-cssstyledeclaration-interface"><span
class=secno>7.3.2 </span>The <code
title="">CSSStyleDeclaration</code> Interface</a>
<li><a href="#the-css2properties-interface"><span class=secno>7.3.3
</span>The <code title="">CSS2Properties</code> Interface</a>
</ul>
</ul>
<li><a href="#css-property-value-apis"><span class=secno>8 </span>CSS
Property Value APIs</a>
<ul class=toc>
<li><a href="#the-elementcssinlinestyle-interface"><span class=secno>8.1
</span>The <code>ElementCSSInlineStyle</code> Interface</a>
<li><a href="#the-viewcss-interface"><span class=secno>8.2 </span>The
<code title="">ViewCSS</code> Interface</a>
</ul>
<li class=no-num><a href="#iana-considerations">IANA Considerations</a>
<ul class=toc>
<li class=no-num><a href="#default-style-"><code>Default-Style</code>
</a>
</ul>
<li class=no-num><a href="#references">References</a>
<li class=no-num><a href="#acknowledgements">Acknowledgements</a>
</ul>
<!--end-toc-->
<h2 id=introduction><span class=secno>1 </span>Introduction</h2>
<p class=issue>...
<h3 id=history><span class=secno>1.1 </span>History</h3>
<p>Several interfaces from DOM Level 2 Style <a
href="http://www.w3.org/mid/Pine.LNX.4.05.10310302134070.1173-100000@lanalana.inria.fr"
title="[CSSOM] CSSValue and related interfaces (message from the CSS
WG)">have been obsoleted</a> because they where thought to be too awkward
for frequent use. This specification no longer contains those features.
<code>DOMImplementationCSS</code> and <code>CSSCharsetRule</code> have
been removed as well as they were not deemed necessary.
<h2 id=conformance><span class=secno>2 </span>Conformance Requirements</h2>
<p>Everything in this specification is normative except for diagrams,
examples, notes and sections marked non-normative.
<p>The key words <em class=ct>must</em>, <em class=ct>must not</em>, <em
class=ct>required</em>, <em class=ct>shall</em>, <em class=ct>shall
not</em>, <em class=ct>should</em>, <em class=ct>should not</em>, <em
class=ct>recommended</em>, <em class=ct>may</em>, and <em
class=ct>optional</em> in the normative parts of this document are to be
interpreted as described in RFC 2119 <a href="#ref-rfc2119">[RFC2119]</a>.</p>
<!-- XXX
<p>The following conformance classes are defined (and considered) by this
specification:</p>
<dl>
<dt><dfn id="conforming-implementation">conforming implementation</dfn></dt>
<dd>A user agent that implements all interfaces described in this
specification and follows all <em class="ct">must</em>-,
<em class="ct">required</em>- and <em class="ct">shall</em>-level of criteria
in this specification.</dd>
<dt><dfn id="conforming-document">conforming document</dfn></dt>
<dd>A document that follows all <em class="ct">must</em>-,
<em class="ct">required</em>- and <em class="ct">shall</em>-level of criteria
in this specification that apply to document authors.</dd>
<dt><dfn id="conforming-authoring-tool">conforming authoring tool</dfn></dt>
<dd>One that produces conforming documents.</dd>
</dl>
-->
<h2 id=terminology><span class=secno>3 </span>Terminology</h2>
<p class=XXX> <dfn id=resolve-a-url>resolve a URL</dfn>, <dfn
id=url>URL</dfn>, <dfn id=content-type-metadata>Content-Type
metadata</dfn>, <dfn id=supported-styling-language>supported styling
language</dfn>, <dfn
id=xml-stylesheet-processing-instruction><code>xml-stylesheet</code>
processing instruction</dfn>, <dfn id=fetch>fetch</dfn>, ...
<p>A <dfn id=color-component-integer>color component integer</dfn> is a
base-ten integer in the range 0-255 using digits 0-9, U+0030 to U+0039, in
the shortest form possible.
<p>A <dfn id=color-component-separator>color component separator</dfn> is a
literal U+002C COMMA followed by a U+0020 SPACE.
<p>When this specification talks about object <code><var>A</var></code>
where <code><var>A</var></code> is actually an interface, it generally
means an object implementing interface <code><var>A</var></code>.
<p>The term <dfn id=whitespace>whitespace</dfn> is used as defined in CSS.
<!--XXX <a href="#ref-css">[CSS]</a>-->
<h2 id=media-queries><span class=secno>4 </span>Media Queries</h2>
<p>Media queries are defined by the Media Queries specification. This
section defines various concepts around media queries, including their API
and serialization form.</p>
<!-- XXX ref -->
<h3 id=parsing-media-queries><span class=secno>4.1 </span>Parsing Media
Queries</h3>
<p>To <dfn id=parse-a-media-query>parse a media query</dfn> for a given
string <var title="">s</var> means to follow the <a
href="#parse-a-list-of-media-queries">parse a list of media queries</a>
steps and return null if more than one media query is returned or a media
query if a single media query is returned.
<p>To <dfn id=parse-a-list-of-media-queries>parse a list of media
queries</dfn> for a given string <var>s</var> into a list of media queries
is defined in the Media Queries specification. Return the list of one or
more media queries that the algorithm defined there gives.</p>
<!-- XXX ref -->
<p class=note>If everything ends up being ignored the list will contain the
media query "<code title="">not all</code>".
<h3 id=serializing-media-queries><span class=secno>4.2 </span>Serializing
Media Queries</h3>
<p>To <dfn id=serialize-a-media-query>serialize a media query</dfn> run
these steps:
<ol>
<li>
<p>Let <var title="">s</var> be the empty string.
<li>
<p>If the media query is negated append the literal string
"<code>not</code>", followed by a U+0020 SPACE character, to <var
title="">s</var>.
<li>
<p>Let <var title="">type</var> be the media query, <span>converted to
ASCII lowercase</span>.
<li>
<p>If the media query does not contain media features append <var
title="">type</var>, to <var>s</var>, then return <var>s</var> and
terminate this algorithm.
<li>
<p>If <var title="">type</var> is not "<code>all</code>" or if the media
query is negated append <var title="">type</var>, followed by a U+0020
SPACE character, followed by "<code>and</code>", followed by a U+0020
SPACE character, to <var title="">s</var>.
<li>
<p>Sort the media features in lexicographical order.
<li>
<p>Then, for each media feature:</p>
<ol>
<li>Append a U+0028 LEFT PARENTHESIS character, followed by the media
feature name, <span>converted to ASCII lowercase</span>, to
<var>s</var>.
<li>
<p>If a value is given append a U+003A COLON (:) character, followed by
a U+0020 SPACE character, followed by the <a
href="#serialize-a-media-feature-value" title="serialize a media
feature value">serialized media feature value</a>, to <var>s</var>.</p>
<li>
<p>Append a U+0029 RIGHT PARENTHESIS character to <var>s</var>.
<li>
<p>If this is not the last media feature append a U+0020 SPACE
character, followed by the literal string "<code>and</code>", followed
by a U+0020 SPACE character, to <var>s</var>.</p>
</ol>
<li>
<p>Return <var>s</var>.
</ol>
<div class=example>
<p>Here are some examples of input (first column) and output (second
column):</p>
<table>
<thead>
<tr>
<th>Input
<th>Output
<tbody>
<tr>
<td><code>not screen and (min-WIDTH:5px) AND (max-width:40px )</code>
<td><code>not screen and (max-width: 40px) and (min-width: 5px)</code>
<tr>
<td><code>all and (color) and (color)</code>
<td><code>(color)</code>
</table>
</div>
<p>To <dfn id=serialize-a-list-of-media-queries>serialize a list of media
queries</dfn> run these steps:
<ol>
<li>
<p>Let <var>s</var> be the empty string.
<li>
<p>If the list is empty return <var>s</var> and terminate this algorithm.
<li>
<p>For each media query in the list:</p>
<ol>
<li>
<p>Append the result of <span title=serializing-media-query>serializing
the media query</span> to <var>s</var>.
<li>
<p>If this is not the last media query append a U+002C COMMA (,)
character, followed by a U+0020 SPACE character to <var>s</var>.
</ol>
<li>
<p>Return <var>s</var>.
</ol>
<h4 id=serializing-media-feature-values><span class=secno>4.2.1
</span>Serializing Media Feature Values</h4>
<p>To <dfn id=serialize-a-media-feature-value>serialize a media feature
value</dfn> named <var title="">v</var> locate <var title="">v</var> in
the first column of the table below and use the serialization format
described in the second column:
<table>
<tbody>
<tr>
<th>Media Feature
<th>Serialization
<tr>
<td><code title="">width</code>
<td>...
<tr>
<td><code title="">height</code>
<td>...
<tr>
<td><code title="">device-width</code>
<td>...
<tr>
<td><code title="">device-height</code>
<td>...
<tr>
<td><code title="">orientation</code>
<td>
<p>If the value is `<code title="">portrait</code>`: "<code
title="">portrait</code>".</p>
<p>If the value is `<code title="">landscape</code>`: "<code
title="">landscape</code>".</p>
<tr>
<td><code title="">aspect-ratio</code>
<td>...
<tr>
<td><code title="">device-aspect-ratio</code>
<td>...
<tr>
<td><code title="">color</code>
<td>...
<tr>
<td><code title="">color-index</code>
<td>...
<tr>
<td><code title="">monochrome</code>
<td>...
<tr>
<td><code title="">resolution</code>
<td>...
<tr>
<td><code title="">scan</code>
<td>
<p>If the value is `<code title="">progressive</code>`: "<code
title="">progressive</code>".</p>
<p>If the value is `<code title="">interlace</code>`: "<code
title="">interlace</code>".</p>
<tr>
<td><code title="">grid</code>
<td>...
</table>
<p>Other specifications can extend this table and vendor-prefixed media
features can have custom serialization formats as well.
<h3 id=comparing-media-queries><span class=secno>4.3 </span>Comparing Media
Queries</h3>
<p>To <dfn id=compare-media-queries>compare media queries</dfn>
<var>m1</var> and <var>m2</var> means to <span title="serializing media
query">serialize</span> them both and return true if they are a
<span>case-sensitive</span> match and false if they are not.
<h3 id=the-medialist-interface><span class=secno>4.4 </span>The <code
title="">MediaList</code> Interface</h3>
<p>An object that implements the <code><a
href="#medialist">MediaList</a></code> interface has an associated <dfn
id=list-of-media-queries>list of media queries</dfn>.</p>
<!-- http://dev.w3.org/2006/webapi/WebIDL/#idl-indexed-properties -->
<pre class=idl>interface <dfn id=medialist>MediaList</dfn> {
stringifier attribute DOMString <a href="#medialist-mediatext" title=medialist-mediatext>mediaText</a>;
readonly attribute unsigned long <a href="#medialist-length" title=medialist-length>length</a>;
getter DOMString <a href="#medialist-item" title=medialist-item>item</a>(unsigned long <var title="">index</var>);
void <a href="#medialist-appendmedium" title=medialist-appendmedium>appendMedium</a>(DOMString <var title="">medium</var>)
void <a href="#medialist-deletemedium" title=medialist-deletemedium>deleteMedium</a>(DOMString <var title="">medium</var>)
};</pre>
<p>The <dfn id=medialist-mediatext
title=medialist-mediatext><code>mediaText</code></dfn> attribute <em
class=ct>must</em>, on getting, return a <a
href="#serialize-a-list-of-media-queries" title="serialize a list of media
queries">serialization</a> of the <span>list of media qeuries</span>.
<p>On setting the <code title=medialist-mediatext><a
href="#medialist-mediatext">mediaText</a></code> attribute these steps <em
class=ct>must</em> be run:
<ol>
<li>
<p>Empty the <a href="#list-of-media-queries">list of media queries</a>.
<li>
<p>If the given value is the empty string terminate these steps.
<li>
<p>Append all the media queries as a result of <a
href="#parse-a-list-of-media-queries" title="parse a list of media
queries">parsing</a> the given value to the <a
href="#list-of-media-queries">list of media queries</a>.
</ol>
<p>The <dfn id=medialist-length
title=medialist-length><code>length</code></dfn> attribute, on getting,
<em class=ct>must</em> return the number of media queries in the <a
href="#list-of-media-queries">list of media queries</a>.
<p>The <dfn id=medialist-item title=medialist-item><code>item(<var
title="">index</var>)</code></dfn> method, when invoked, <em
class=ct>must</em> return the item in the list given by <var>index</var>,
or <code>null</code>, if <var>index</var> is greater than or equal to the
number of items in the list.</p>
<!-- XXX need consistency here WebIDL? list of media queries? -->
<p>The <dfn id=medialist-appendmedium
title=medialist-appendmedium><code>appendMedium(<var
title="">medium</var>)</code></dfn> method <em class=ct>must</em>, when
invoked, run these steps:
<ol>
<li>
<p>Let <var title="">m</var> be the result of <a
href="#parse-a-media-query" title="parse a media query">parsing</a> the
given value.
<li>
<p>If <var title="">m</var> is null terminate these steps.
<li>
<p>If <a href="#compare-media-queries" title="compare media
queries">comparing</a> <var title="">m</var> with any of the media
queries in the <a href="#list-of-media-queries">list of media
queries</a> returns true terminate these steps.
<li>
<p>Append <var title="">m</var> to the <a
href="#list-of-media-queries">list of media queries</a>.
</ol>
<p>The <dfn id=medialist-deletemedium
title=medialist-deletemedium><code>deleteMedium(<var
title="">medium</var>)</code></dfn> method <em class=ct>must</em>, when
invoked, run these steps:
<ol>
<li>
<p>Let <var title="">m</var> be the result of <a
href="#parse-a-media-query" title="parse a media query">parsing</a> the
given value.
<li>
<p>If <var title="">m</var> is null terminate these steps.
<li>
<p>Remove any media query from the <a href="#list-of-media-queries">list
of media queries</a> for which <a href="#compare-media-queries"
title="compare media queries">comparing</a> the media query with <var
title="">m</var> returns true.
</ol>
<h3 id=creating-a-medialist-object><span class=secno>4.5 </span>Creating a
<code title="">MediaList</code> Object</h3>
<p>To <dfn id=create-a-medialist-object>create a <code>MediaList</code>
object</dfn> from <var title="">s</var> run these steps:
<ol>
<li>
<p>Create a new <code><a href="#medialist">MediaList</a></code> object.
<li>
<p>Set its <a href="#medialist-mediatext"
title=medialist-mediatext>mediaText</a> attribute to <var
title="">s</var>.
<li>
<p>Return the newly created <code><a
href="#medialist">MediaList</a></code> object.
</ol>
<h2 id=selectors><span class=secno>5 </span>Selectors</h2>
<p>Selectors are defined in the Selectors specification. This section
defines how to serialize them.</p>
<!-- XXX ref -->
<p>To <dfn id=parse-a-group-of-selectors>parse a group of selectors</dfn>
means to parse the value using the <code title="">selectors_group</code>
production defined in the Selectors specification and return either a
group of selectors if parsing did not fail or null if parsing did fail.</p>
<!-- XXX ref -->
<p>To <dfn id=serialize-a-group-of-selectors>serialize a group of
selectors</dfn> run these steps:
<ol>
<li>
<p>Remove leading and trailing <a href="#whitespace">whitespace</a>.
<li>
<p>Replace one or more consecutive <a href="#whitespace">whitespace</a>
characters with a single U+0020 SPACE character.
<li>
<p>Make sure combinators other than the descendant combinator are
preceded and followed by a single U+0020 SPACE character (and not more).
<li>
<p>Make sure each U+002C COMMA (,) character is followed by a single
U+0020 SPACE character (and not more).
<li>
<p>Convert pseudo-classes and pseudo-elements to their canonical form as
given in the specification.</p>
<p class=note>E.g. <code>:HOver</code> becomes <code>:hover</code> and
<code>:befoRe</code> becomes <code>::before</code>.</p>
<li>
<p class=XXX>Hmm, what about pseudo-classes taking arguments? Attribute
selectors? Namespace prefixes?
</ol>
<h2 id=style-sheets><span class=secno>6 </span>Style Sheets</h2>
<h3 id=style-sheet0><span class=secno>6.1 </span>Style Sheet</h3>
<p>A <dfn id=style-sheet>style sheet</dfn> is an abstract concept that
represents any kind of style sheet. In the DOM a <a
href="#style-sheet">style sheet</a> is a <code><a
href="#stylesheet">StyleSheet</a></code> object. A <a
href="#style-sheet">style sheet</a> has a number of associated properties:
<dl>
<dt><dfn id=style-sheet-type>style sheet type</dfn>
<dd>
<p>The <a href="#content-type-metadata">Content-Type metadata</a> of the
<a href="#style-sheet">style sheet</a>.
<dt><dfn id=style-sheet-location>style sheet location</dfn>
<dd>
<p>The <a href="#url">URL</a> of the <a href="#style-sheet">style
sheet</a> or null if the <a href="#style-sheet">style sheet</a> was
embedded.
<dt><dfn id=style-sheet-node>style sheet node</dfn>
<dd>
<p>The DOM node associated with the <a href="#style-sheet">style
sheet</a> or null if there is no associated DOM node.
<dt><dfn id=style-sheet-parent>style sheet parent</dfn>
<dd>
<p>The <a href="#style-sheet">style sheet</a> that is the parent of the
<a href="#style-sheet">style sheet</a>.
</dd>
<!-- XXX what if imported twice? -->
<dt><dfn id=style-sheet-media>style sheet media</dfn>
<dd>
<p>The <code><a href="#medialist">MediaList</a></code> object associated
with the <a href="#style-sheet">style sheet</a>.</p>
<p>If this property is set to a string run the <a
href="#create-a-medialist-object">create a <code>MediaList</code>
object</a> steps for that string and associate the returned object with
the <a href="#style-sheet">style sheet</a>.</p>
<dt><dfn id=style-sheet-title>style sheet title</dfn>
<dd>
<p>The title of the <a href="#style-sheet">style sheet</a>. It is said to
be empty if the title is the empty string.</p>
<div class=example>
<p>In these examples the <a href="#style-sheet-title">style sheet
title</a> ends up being empty:</p>
<pre><style title=""> body { background:papayawhip } </style></pre>
<pre><style> body { background:orange } </style></pre>
</div>
<dt><dfn id=style-sheet-alternate-flag>style sheet alternate flag</dfn>
<dd>
<p>Either true or false. False by default.</p>
<div class=example>
<p>The following <a href="#style-sheet" title="style sheet">style
sheets</a> have their <a href="#style-sheet-alternate-flag">style sheet
alternate flag</a> set:</p>
<pre><code><?xml-stylesheet alternate="yes" title="x" href="data:text/css,…"?></code></pre>
<pre><code><link rel="alternate stylesheet" title="x" href="data:text/css,…"></code></pre>
</div>
<dt><dfn id=style-sheet-disabled-flag>style sheet disabled flag</dfn>
<dd>
<p>Either true or false. False by default.</p>
<p class=note>Even when false it does not necessarily mean that the <a
href="#style-sheet">style sheet</a> is actually rendered.</p>
</dl>
<p>When you are to <a href="#create-a-style-sheet">create a style sheet</a>
the above properties are to be set to their proper values.</p>
<!-- same-origin restrictions -->
<h4 id=the-stylesheet-interface><span class=secno>6.1.1 </span>The <code
title="">StyleSheet</code> Interface</h4>
<p>In the DOM a <a href="#style-sheet">style sheet</a> is represented by an
object that implements the <code><a
href="#stylesheet">StyleSheet</a></code> interface.
<pre class=idl>interface <dfn id=stylesheet>StyleSheet</dfn> {
readonly attribute DOMString <a href="#stylesheet-type" title=stylesheet-type>type</a>;
readonly attribute DOMString <a href="#stylesheet-href" title=stylesheet-href>href</a>;
readonly attribute Node <a href="#stylesheet-ownernode" title=stylesheet-ownernode>ownerNode</a>;
readonly attribute <a href="#stylesheet">StyleSheet</a> <a href="#stylesheet-parentstylesheet" title=stylesheet-parentstylesheet>parentStyleSheet</a>;
readonly attribute DOMString <a href="#stylesheet-title" title=stylesheet-title>title</a>;
[PutForwards=mediaText] readonly attribute <a href="#medialist">MediaList</a> <a href="#stylesheet-media" title=stylesheet-media>media</a>;
attribute boolean <a href="#stylesheet-disabled" title=stylesheet-disabled>disabled</a>;
};</pre>
<p>The <dfn id=stylesheet-type
title=stylesheet-type><code>type</code></dfn> attribute <em
class=ct>must</em> return the <a href="#style-sheet-type">style sheet
type</a>.
<p>The <dfn id=stylesheet-href
title=stylesheet-href><code>href</code></dfn> attribute <em
class=ct>must</em> return the <a href="#style-sheet-location">style sheet
location</a>.
<p>The <dfn id=stylesheet-ownernode
title=stylesheet-ownernode><code>ownerNode</code></dfn> attribute <em
class=ct>must</em> return the <a href="#style-sheet-node">style sheet
node</a>.
<p>The <dfn id=stylesheet-parentstylesheet
title=stylesheet-parentstylesheet><code>parentStyleSheet</code></dfn>
attribute <em class=ct>must</em> return the <a
href="#style-sheet-parent">style sheet parent</a>.
<p>The <dfn id=stylesheet-title
title=stylesheet-title><code>title</code></dfn> attribute <em
class=ct>must</em> return the <a href="#style-sheet-title">style sheet
title</a>.
<p>The <dfn id=stylesheet-media
title=stylesheet-media><code>media</code></dfn> attribute <em
class=ct>must</em> return the <a href="#style-sheet-media">style sheet
media</a>.
<p>The <dfn id=stylesheet-disabled
title=stylesheet-disabled><code>disabled</code></dfn> attribute <em
class=ct>must</em>, on getting, return the <a
href="#style-sheet-disabled-flag">style sheet disabled flag</a>. On
setting, it <em class=ct>must</em> set the <a
href="#style-sheet-disabled-flag">style sheet disabled flag</a> to the
given value.
<h3 id=style-sheet-collections><span class=secno>6.2 </span>Style Sheet
Collections</h3>
<p>Below various new concepts are defined that are associated with each
<code>Document</code> object.
<p>Each <code>Document</code> has an associated list of zero or more <a
href="#style-sheet" title="style sheet">style sheets</a>, named the <dfn
id=document-style-sheets>document style sheets</dfn>. This is an ordered
list that contains all <a href="#style-sheet" title="style sheet">style
sheets</a> associated with the <code>Document</code>, in <span>tree
order</span>, with <a href="#style-sheet" title="style sheet">style
sheets</a> created from HTTP <code title=http-link>Link</code> headers
first, if any, in header order.
<p>To <dfn id=create-a-style-sheet>create a style sheet</dfn>, run these
steps:
<ol>
<li>
<p>Create a new <a href="#style-sheet">style sheet</a> object and set its
properties as specified.
<li>
<p>Then run the <a href="#add-a-style-sheet">add a style sheet</a> steps
for the newly created <a href="#style-sheet">style sheet</a>.
</ol>
<p>To <dfn id=add-a-style-sheet>add a style sheet</dfn>, run these steps:
<ol>
<li>
<p>Add the <a href="#style-sheet">style sheet</a> to the list of <a
href="#document-style-sheets">document style sheets</a> at the
appropriate location. The remainder of these steps deal with the <a
href="#style-sheet-disabled-flag">style sheet disabled flag</a>.
<li>
<p>If the <a href="#style-sheet-disabled-flag">style sheet disabled
flag</a> is true terminate these steps.
<li>
<p>If the <a href="#style-sheet-title">style sheet title</a> is
non-empty, the <a href="#style-sheet-alternate-flag">style sheet
alternate flag</a> is false, and <a
href="#preferred-style-sheet-set-name">preferred style sheet set
name</a> is the empty string <a
href="#change-the-preferred-style-sheet-set-name">change the preferred
style sheet set name</a> to the <a href="#style-sheet-title">style sheet
title</a>.
<li>
<p>If any of the following is true set the <a
href="#style-sheet-disabled-flag">style sheet disabled flag</a> to false
and terminate these steps:</p>
<ul>
<li>
<p>The <a href="#style-sheet-title">style sheet title</a> is empty.
<li>
<p>The <a href="#last-style-sheet-set-name">last style sheet set
name</a> is null and the <a href="#style-sheet-title">style sheet
title</a> is a <span>case-sensitive</span> match for the <a
href="#preferred-style-sheet-set-name">preferred style sheet set
name</a>.
<li>
<p>The <a href="#style-sheet-title">style sheet title</a> is a
<span>case-sensitive</span> match for the <a
href="#last-style-sheet-set-name">last style sheet set name</a>.
</ul>
<li>
<p>Set the <a href="#style-sheet-disabled-flag">style sheet disabled
flag</a> to true.
</ol>
<p>A <dfn id=persistent-style-sheet>persistent style sheet</dfn> is a <a
href="#style-sheet">style sheet</a> from the <a
href="#document-style-sheets">document style sheets</a> whose <a
href="#style-sheet-title">style sheet title</a> is the empty string and
whose <a href="#style-sheet-alternate-flag">style sheet alternate flag</a>
is false.
<p>A <dfn id=style-sheet-set>style sheet set</dfn> is an ordered collection
of one or more <a href="#style-sheet" title="style sheet">style sheets</a>
from the <a href="#document-style-sheets">document style sheets</a> which
have an identical <a href="#style-sheet-title">style sheet title</a> that
is not the empty string.
<p>A <dfn id=style-sheet-set-name>style sheet set name</dfn> is the <a
href="#style-sheet-title">style sheet title</a> the <a
href="#style-sheet-set">style sheet set</a> has in common.
<p>An <dfn id=enabled-style-sheet-set>enabled style sheet set</dfn> is a <a
href="#style-sheet-set">style sheet set</a> of which each <a
href="#style-sheet">style sheet</a> has its <a
href="#style-sheet-disabled-flag">style sheet disabled flag</a> set to
false.
<p>To <dfn id=enable-a-style-sheet-set>enable a style sheet set</dfn> with
name <var title="">name</var>, run these steps:
<ol>
<li>
<p>If <var title="">name</var> is the empty string set the <a
href="#style-sheet-disabled-flag">style sheet disabled flag</a> for each
<a href="#style-sheet">style sheet</a> that is in a <a
href="#style-sheet-set">style sheet set</a> to true and terminate these
steps.
<li>
<p>Set the <a href="#style-sheet-disabled-flag">style sheet disabled
flag</a> for each <a href="#style-sheet">style sheet</a> in a <a
href="#style-sheet-set">style sheet set</a> whose <a
href="#style-sheet-set-name">style sheet set name</a> is a
case-sensitive match for <var title="">name</var> to false and set it to
false for all other <a href="#style-sheet" title="style sheet">style
sheets</a> in a <a href="#style-sheet-set">style sheet set</a>.
</ol>
<p>To <dfn id=select-a-style-sheet-set>select a style sheet set</dfn> with
name <var title="">name</var>, run these steps:
<ol>
<li>
<p><a href="#enable-a-style-sheet-set">Enable a style sheet set</a> with
name <var title="">name</var>.
<li>
<p>Set <a href="#last-style-sheet-set-name">last style sheet set name</a>
to <var title="">name</var>.
</ol>
<p>A <dfn id=last-style-sheet-set-name>last style sheet set name</dfn> is a
concept to determine what <a href="#style-sheet-set">style sheet set</a>
was last <a href="#select-a-style-sheet-set" title="select a style sheet
set">selected</a>. Initially its value is null.