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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 rel="stylesheet" href="http://www.w3.org/StyleSheets/TR/W3C-[STATUS]">
</head>
<body class="draft">
<div class="head">
<h1 id="cssom">CSSOM</h1>
<h2 class="no-num no-toc" id="">[LONGSTATUS] [DATE: 3 August 2002]</h2>
<dl>
<dt>This Version:</dt>
<dd><a href="[VERSION]/">http://www.w3.org/TR/[YEAR]/ED-cssom-[CDATE]/</a></dd>
<dt>Latest Version:</dt>
<dd><a href="http://www.w3.org/TR/cssom/">http://www.w3.org/TR/cssom/</a></dd>
<dt>Latest Editor's draft:</dt>
<dd><a href="http://dev.w3.org/csswg/cssom/">http://dev.w3.org/csswg/cssom/</a></dd>
<dt>Previous Version:</dt>
<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></dd>
<dt>Editor:</dt>
<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>></dd>
</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.</p>
<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>
<!--status-->
<h2 class="no-num no-toc" id="toc">Table of Contents</h2>
<!--toc-->
<h2 id="introduction">Introduction</h2>
<p class="issue">...</p>
<h3 id="history">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.</p>
<h2 id="conformance">Conformance Requirements</h2>
<p>Everything in this specification is normative except for diagrams,
examples, notes and sections marked non-normative.</p>
<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">Terminology</h2>
<p class="XXX">
<dfn>resolve a URL</dfn>,
<dfn>case-sensitive</dfn>,
<dfn>ASCII case-insensitive</dfn>,
<dfn>URL</dfn>,
<dfn>Content-Type metadata</dfn>,
<dfn>supported styling language</dfn>,
<dfn><code>xml-stylesheet</code> processing instruction</dfn>,
<dfn>fetch</dfn>, ...
</p>
<p>A <dfn>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>
<p>A <dfn>color component separator</dfn> is a literal U+002C COMMA followed
by a U+0020 SPACE.</p>
<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>
<p>The term <dfn id="whitespace">whitespace</dfn> is used as defined in
CSS. <!--XXX <a href="#ref-css">[CSS]</a>--></p>
<h2>Media Queries</h2>
<p><dfn id="media queries">Media queries</dfn> are defined by the
Media Queries specification. This section defines various concepts around
media queries, including their API and serialization form.</p>
<!-- XXX maybe not a <dfn> -->
<!-- XXX ref -->
<h3>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
<span>parse a list of media queries</span> steps and return null if more
than one media query is returned or a media query if a
single media query is returned.</p>
<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>".</p>
<h3>Serializing Media Queries</h3>
<p>To
<dfn id="serialize-a-media-query">serialize a media query</dfn> run these
steps:</p>
<ol>
<li><p>Let <var title="">s</var> be the empty string.</p></li>
<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>.</p></li>
<li><p>Let <var title="">type</var> be the media query,
<span>converted to ASCII lowercase</span>.</p></li>
<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.</p></li>
<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>.</p></li>
<li><p>Sort the media features in lexicographical order.</p></li>
<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>.</p></li>
<li><p>If a value is given append a U+003A COLON (:)
character, followed by a U+0020 SPACE character, followed by the
<span title="serialize a media feature value">serialized media feature value</span>,
to <var>s</var>.</p>
<li><p>Append a U+0029 RIGHT PARENTHESIS character to
<var>s</var>.</p></li>
<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>
<li><p>Return <var>s</var>.</p></li>
</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:</p>
<ol>
<li><p>Let <var>s</var> be the empty string.</p></li>
<li><p>If the list is empty return <var>s</var> and terminate this
algorithm.</p></li>
<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>.</p></li>
<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>.</p></li>
</ol>
</li>
<li><p>Return <var>s</var>.</p></li>
</ol>
<h4>Serializing Media Feature Values</h4>
<p class="XXX">This should probably be done in terms of mapping it to
serializing CSS values as media features are defined in terms of CSS
values after all.</p>
<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:</p>
<table>
<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.</p>
<h3>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.</p>
<h3>The <code title="">MediaList</code> Interface</h3>
<p>An object that implements the <code>MediaList</code> interface has an
associated <dfn>collection of media queries</dfn>.</p>
<!-- http://dev.w3.org/2006/webapi/WebIDL/#idl-indexed-properties -->
<pre class="idl">interface <dfn>MediaList</dfn> {
stringifier attribute DOMString <span title="medialist-mediatext">mediaText</span>;
readonly attribute unsigned long <span title="medialist-length">length</span>;
getter DOMString <span title="medialist-item">item</span>(unsigned long <var title="">index</var>);
void <span title="medialist-appendmedium">appendMedium</span>(DOMString <var title="">medium</var>)
void <span title="medialist-deletemedium">deleteMedium</span>(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
<span title="serialize a list of media queries">serialization</span> of
the <span>list of media qeuries</span>.</p>
<p>On setting the <code title="medialist-mediatext">mediaText</code>
attribute these steps <em class="ct">must</em> be run:</p>
<ol>
<li><p>Empty the <span>collection of media queries</span>.</p></li>
<li><p>If the given value is the empty string terminate these
steps.</p></li>
<li><p>Append all the media queries as a result of
<span title="parse a list of media queries">parsing</span> the given
value to the <span>collection of media queries</span>.</p></li>
</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 <span>collection of media queries</span>.</p>
<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:</p>
<ol>
<li><p>Let <var title="">m</var> be the result of
<span title="parse a media query">parsing</span> the given
value.</p></li>
<li><p>If <var title="">m</var> is null terminate these steps.</p></li>
<li><p>If <span title="compare media queries">comparing</span>
<var title="">m</var> with any of the media queries in the
<span>collection of media queries</span> returns true terminate these
steps.</p></li>
<li><p>Append <var title="">m</var> to the
<span>collection of media queries</span>.</p></li>
</ol>
<p>The
<dfn id="medialist-deletemedium" title="medialist-deletemedium"><code>deleteMedium(<var title="">medium</var>)</code></dfn&g
10BC8
t;
method <em class="ct">must</em>, when invoked, run these steps:</p>
<ol>
<li><p>Let <var title="">m</var> be the result of
<span title="parse a media query">parsing</span> the given
value.</p></li>
<li><p>If <var title="">m</var> is null terminate these steps.</p></li>
<li><p>Remove any media query from the <span>collection of media queries</span>
for which <span title="compare media queries">comparing</span> the media
query with <var title="">m</var> returns true.</p></li>
</ol>
<h3>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:</p>
<ol>
<li><p>Create a new <code>MediaList</code> object.</p></li>
<li><p>Set its <span title="medialist-mediatext">mediaText</span>
attribute to <var title="">s</var>.</p></li>
<li><p>Return the newly created <code>MediaList</code> object.</p></li>
</ol>
<h2>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:</p>
<!-- http://dump.testsuite.org/2009/cssom/serializing-selectors.htm -->
<ol>
<!-- XXX say something about CSS character escapes? -->
<li><p>Remove leading and trailing <span>whitespace</span>.</p></li>
<li><p>Replace one or more consecutive <span>whitespace</span> characters
with a single U+0020 SPACE character.</p></li>
<li><p>Make sure combinators other than the descendant combinator are
preceded and followed by a single U+0020 SPACE character (and not
more).</p></li>
<li><p>Make sure each U+002C COMMA (,) character is followed by a
single U+0020 SPACE character (and not more).</p></li>
<li><p>If there is no default namespace and the namespace prefix of a
<span>type selector</span> or <span>universal selector</span> is set to a
U+002A ASTERISK (*) character remove the namespace component of that
<span>type selector</span> or <span>universal selector</span>.</p></li>
<!-- XXX namespace refs? -->
<li><p>Remove any
<span title="universal selector">universal selectors</span> that can be
omitted.</p></li>
<li>
<p>Follow these rules for serializing attribute selectors:</p>
<ul>
<li><p>If there is no namespace prefix (which includes the asterisk)
remove the U+007C VERTICAL LINE (|) before the attribute name if it is
present.</p></li>
<!-- XXX ref namespace prefix? -->
<li><p>If an identifier was given as value insert a leading and
trailing U+0022 QUOTATION MARK (") character around the identifier and
escape any U+0022 QUOTATION MARK (") characters in the value by
inserting a U+005C REVERSE SOLIDUS (\) character in front of
them.</p></li>
<!-- XXX or does this happen during parsing -->
</ul>
</li>
<li>
<p>Pseudo-classes without arguments and pseudo-elements are serialized
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>.</span></p>
</li>
<li>
<p>The rules for pseudo-classes with arguments are to serialize their
name to their canonical name as given in the specification, remove any
leading and trailing <span>whitespace</span> around the argument, and
serialize the value as follows:</p>
<dl>
<dt>If the pseudo-class is <code title="">:lang()</code></dt>
<dd><p>The literal value.</p></dd>
<dt>If the pseudo-class is <code title="">:nth-child()</code>,
<code title="">:nth-last-child()</code>,
<code title="">:nth-of-type()</code>, or
<code title="">:nth-last-of-type()</code></dt>
<dd>
<ol>
<li><p>If the value is odd let the value be
"<code title="">2n+1</code>".</p></li>
<li><p>If the value is even let the value be
"<code title="">2n</code>".</p></li>
<li><p>If <var title="">a</var> is zero let the value be
<var title="">b</var> serialized as string.</p></li>
<!-- XXX serialize integer -->
<li><p>If <var title="">a</var> is one or minus one and
<var title="">b</var> is zero let the value be
"<code title="">n</code>".</p></li>
<li><p>If <var title="">a</var> is one or minus one let the value be
"<code title="">n</code>" followed by a U+002B PLUS SIGN (+)
character if <var title="">b</var> is positive, followed by
<var title="">b</var> serialized as string.</p></li>
<!-- XXX serialize integer -->
<li><p>If <var title="">b</var> is zero let the value be
<var title="">a</var> serialized as string followed by
"<code title="">n</code>".</p></li>
<!-- XXX serialize integer -->
<li><p>Otherwise let the value be
<var title="">a</var> serialized as string followed by
"<code title="">n</code>" followed by a U+002B PLUS SIGN (+)
character if <var title="">b</var> is positive, followed by
<var title="">b</var> serialized as string.</p></li>
<!-- XXX serialize integer -->
</ol>
</dd>
<dt>If the pseudo-class is <code title="">:not()</code></dt>
<dd><p>The result of serializing the value using the rules for
<span title="serialize a group of selectors">serializing a group of selectors</span>.</p></dd>
<dt>Any other pseudo-class</dt>
<dd><p class="XXX">Hopefully Selectors Level 4 defines serialization itself.</p></dd>
</dl>
</li>
</ol>
<h2>Style Sheets</h2>
<h3>Style Sheet</h3>
<!-- XXX
element inserted into the DOM, style sheet created, element removed from
the DOM, what happens to StyleSheet?
-->
<p>A <dfn id="style-sheet">style sheet</dfn> is an abstract concept that
represents any kind of style sheet. In the DOM a <span>style sheet</span>
is a <code>StyleSheet</code> object. A <span>style sheet</span> has a
number of associated properties:</p>
<dl>
<dt><dfn id="style-sheet-type">style sheet type</dfn></dt>
<dd><p>The <span>Content-Type metadata</span> of the
<span>style sheet</span>.</p></dd>
<dt><dfn id="style-sheet-location">style sheet location</dfn></dt>
<dd><p>The <span>URL</span> of the <span>style sheet</span> or null if
the <span>style sheet</span> was embedded.</p></dd>
<dt><dfn id="style-sheet-node">style sheet node</dfn></dt>
<dd><p>The DOM node associated with the <span>style sheet</span> or
null if there is no associated DOM node.</p></dd>
<dt><dfn id="style-sheet-parent">style sheet parent</dfn></dt>
<dd><p>The <span>style sheet</span> that is the parent of the
<span>style sheet</span>.</p></dd>
<dt><dfn id="style-sheet-media">style sheet media</dfn></dt>
<dd>
<p>The <code>MediaList</code> object associated with the
<span>style sheet</span>.</p>
<p>If this property is set to a string run the
<span>create a <code>MediaList</code> object</span> steps for that
string and associate the returned object with the
<span>style sheet</span>.</p>
</dd>
<dt><dfn id="style-sheet-title">style sheet title</dfn></dt>
<dd>
<p>The title of the <span>style sheet</span>. It is said to be empty
if the title is the empty string.</p>
<div class="example">
<p>In these examples the <span>style sheet title</span> ends up being
empty:</p>
<pre><style title=""> body { background:papayawhip } </style></pre>
<pre><style> body { background:orange } </style></pre>
</div>
</dd>
<dt><dfn id="style-sheet-alternate-flag">style sheet alternate flag</dfn></dt>
<dd>
<p>Either true or false. False by default.</p>
<div class="example">
<p>The following <span title="style sheet">style sheets</span> have
their <span>style sheet alternate flag</span> 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>
</dd>
<dt><dfn>style sheet disabled flag</dfn></dt>
<dd>
<p>Either true or false. False by default.</p>
<p class="note">Even when false it does not necessarily mean that the
<span>style sheet</span> is actually rendered.</p>
</dd>
</dl>
<p>When you are to <span>create a style sheet</span> the above properties
are to be set to their proper values.</p>
<!-- same-origin restrictions -->
<h4>The <code title="">StyleSheet</code> Interface</h4>
<p>In the DOM a <span>style sheet</span> is represented by an object that
implements the <code>StyleSheet</code> interface.</p>
<pre class="idl">interface <dfn id="stylesheet">StyleSheet</dfn> {
readonly attribute DOMString <span title="stylesheet-type">type</span>;
readonly attribute DOMString <span title="stylesheet-href">href</span>;
readonly attribute Node <span title="stylesheet-ownernode">ownerNode</span>;
readonly attribute <span>StyleSheet</span> <span title="stylesheet-parentstylesheet">parentStyleSheet</span>;
readonly attribute DOMString <span title="stylesheet-title">title</span>;
[PutForwards=mediaText] readonly attribute <span>MediaList</span> <span title="stylesheet-media">media</span>;
attribute boolean <span title="stylesheet-disabled">disabled</span>;
};</pre>
<p>The
<dfn id="stylesheet-type" title="stylesheet-type"><code>type</code></dfn>
attribute <em class="ct">must</em> return the
<span>style sheet type</span>.</p>
<p>The
<dfn id="stylesheet-href" title="stylesheet-href"><code>href</code></dfn>
attribute <em class="ct">must</em> return the
<span>style sheet location</span>.</p>
<p>The
<dfn id="stylesheet-ownernode" title="stylesheet-ownernode"><code>ownerNode</code></dfn>
attribute <em class="ct">must</em> return the
<span>style sheet node</span>.</p>
<p>The
<dfn id="stylesheet-parentstylesheet" title="stylesheet-parentstylesheet"><code>parentStyleSheet</code></dfn>
attribute <em class="ct">must</em> return the
<span>style sheet parent</span>.</p>
<p>The
<dfn id="stylesheet-title" title="stylesheet-title"><code>title</code></dfn>
attribute <em class="ct">must</em> return the
<span>style sheet title</span>.</p>
<p>The
<dfn id="stylesheet-media" title="stylesheet-media"><code>media</code></dfn>
attribute <em class="ct">must</em> return the
<span>style sheet media</span>.</p>
<p>The
<dfn id="stylesheet-disabled" title="stylesheet-disabled"><code>disabled</code></dfn>
attribute <em class="ct">must</em>, on getting, return the
<span>style sheet disabled flag</span>. On setting, it
<em class="ct">must</em> set the <span>style sheet disabled flag</span> to
the given value.</p>
<h3>Style Sheet Collections</h3>
<p>Below various new concepts are defined that are associated with each
<code>Document</code> object.</p>
<p>Each <code>Document</code> has an associated list of zero or more
<span title="style sheet">style sheets</span>, named the
<dfn id="document-style-sheets">document style sheets</dfn>. This is
an ordered list that contains all
<span title="style sheet">style sheets</span> associated with the
<code>Document</code>, in <span>tree order</span>, with
<span title="style sheet">style sheets</span> created from HTTP
<code title="http-link">Link</code> headers first, if any, in header
order.</p>
<p>To <dfn id="create-a-style-sheet">create a style sheet</dfn>, run these
steps:</p>
<ol>
<li><p>Create a new <span>style sheet</span> object and set its
properties as specified.</p></li>
<li><p>Then run the <span>add a style sheet</span> steps for the newly
created <span>style sheet</span>.</p></li>
</ol>
<p>To <dfn id="add-a-style-sheet">add a style sheet</dfn>, run these
steps:</p>
<ol>
<li><p>Add the <span>style sheet</span> to the list of
<span>document style sheets</span> at the appropriate location. The
remainder of these steps deal with the
<span>style sheet disabled flag</span>.</p></li>
<li><p>If the <span>style sheet disabled flag</span> is true terminate
these steps.</p></li>
<li><p>If the <span>style sheet title</span> is non-empty, the
<span>style sheet alternate flag</span> is false, and
<span>preferred style sheet set name</span> is the empty string
<span>change the preferred style sheet set name</span> to the
<span>style sheet title</span>.</p></li>
<li>
<p>If any of the following is true set the
<span>style sheet disabled flag</span> to false and terminate these
steps:</p>
<ul>
<li><p>The <span>style sheet title</span> is empty.</p></li>
<li><p>The <span>last style sheet set name</span> is null and the
<span>style sheet title</span> is a <span>case-sensitive</span> match
for the <span>preferred style sheet set name</span>.</p></li>
<li><p>The <span>style sheet title</span> is a
<span>case-sensitive</span> match for the
<span>last style sheet set name</span>.</p></li>
</ul>
</li>
<li><p>Set the <span>style sheet disabled flag</span> to true.</p></li>
</ol>
<p>A <dfn id="persistent-style-sheet">persistent style sheet</dfn> is a
<span>style sheet</span> from the <span>document style sheets</span>
whose <span>style sheet title</span> is the empty string and whose
<span>style sheet alternate flag</span> is false.</p>
<p>A <dfn id="style-sheet-set">style sheet set</dfn> is an ordered
collection of one or more <span title="style sheet">style sheets</span>
from the <span>document style sheets</span> which have an identical
<span>style sheet title</span> that is not the empty string.</p>
<p>A <dfn id="style-sheet-set-name">style sheet set name</dfn> is the
<span>style sheet title</span> the <span>style sheet set</span> has in
common.</p>
<p>An <dfn id="enabled-style-sheet-set">enabled style sheet set</dfn> is a
<span>style sheet set</span> of which each <span>style sheet</span> has
its <span>style sheet disabled flag</span> set to false.</p>
<p>To <dfn id="enable-a-style-sheet-set">enable a style sheet set</dfn>
with name <var title="">name</var>, run these steps:</p>
<ol>
<li><p>If <var title="">name</var> is the empty string set the
<span>style sheet disabled flag</span> for each <span>style sheet</span>
that is in a <span>style sheet set</span> to true and terminate these
steps.</p></li>
<li><p>Set the <span>style sheet disabled flag</span> for each
<span>style sheet</span> in a <span>style sheet set</span> whose
<span>style sheet set name</span> is a case-sensitive match for
<var title="">name</var> to false and set it to false for all other
<span title="style sheet">style sheets</span> in a
<span>style sheet set</span>.</p></li>
</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:</p>
<ol>
<li><p><span>Enable a style sheet set</span> with name
<var title="">name</var>.</p></li>
<li><p>Set <span>last style sheet set name</span> to
<var title="">name</var>.</p></li>
</ol>
<p>A <dfn id="last-style-sheet-set-name">last style sheet set name</dfn>
is a concept to determine what <span>style sheet set</span> was last
<span title="select a style sheet set">selected</span>. Initially its
value is null.</p>
<p>A
<dfn id="preferred-style-sheet-set-name">preferred style sheet set name</dfn>
is a concept to determine which
<span style="style sheet">style sheets</span> need to have their
<span>style sheet disabled flag</span> set to false. Initially its value
is the empty string.
<p>To
<dfn id="change-the-preferred-style-sheet-set-name">change the preferred style sheet set name</dfn>
with name <var title="">name</var>, run these steps:</p>
<ol>
<li><p>Let the <span>preferred style sheet set name</span> be
<var title="">current</var>.</p></li>
<li><p>Set <span>preferred style sheet set name</span> to
<var title="">name</var>.</p></li>
<li><p>If <var title="">name</var> is not a <span>case-sensitive</span>
match for <var title="">current</var> and
<span>last style sheet set name</span> is null
<span>enable a style sheet set</span> with name
<var title="">new</var>.</p></li>
</ol>
<!-- XXX ought to define "applied"
thoughts:
depends on disabled flag, alternate flag, media queries, sheesh
-->
<h4>The HTTP <code title="">Default-Style</code> Header</h4>
<p>The HTTP <code title="http-default-style">Default-Style</code> header
can be used to set the <span>preferred style sheet set name</span>
influencing which <span>style sheet set</span> is (initially) the
<span>enabled style sheet set</span>.</p>
<p>For each HTTP <code title="http-default-style">Default-Style</code>
header, in header order, the user agent <em class="ct">must</em>
<span>change the preferred style sheet set name</span> with name being the
value of the header.</p>
<h4>The <code title="">StyleSheetList</code> Sequence</h4>
<p>The sequence parameterized type represents an ordered collection of
<span title="style sheet">style sheets</span>.</p>
<pre class="idl">typedef sequence<<span>StyleSheet</span>> <dfn>StyleSheetList</dfn>;</pre>
<!--
<pre class="idl">interface <dfn>StyleSheetList</dfn> {
readonly attribute unsigned long <span title="stylesheetlist-length">length</span>;
getter <span>StyleSheet</span> <span title="stylesheetlist-item">item</span>(unsigned long <var title="">index</var>);
};</pre>
<p>The
<dfn id="stylesheetlist-length" title="stylesheetlist-length"><code>length</code></dfn>
attribute, on getting, <em class="ct">must</em> return the number of
objects currently in the list.</p>
<p>The
<dfn id="stylesheetlist-item" title="stylesheetlist-item"><code>item(<var title="">index</var>)</code></dfn>
method, when invoked, <em class="ct">must</em> return the
<code>StyleSheet</code> object 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>
-->
<h4>The <code title="">DocumentStyle</code> Interface</h4>
<!-- https://bugzilla.mozilla.org/show_bug.cgi?id=200930 (FIXED) -->
<pre class="idl">interface <dfn>DocumentStyle</dfn> {
readonly attribute <span>StyleSheetList</span> <span>styleSheets</span>;
attribute DOMString? <span>selectedStyleSheetSet</span>;
readonly attribute DOMString? <span>lastStyleSheetSet</span>;
readonly attribute DOMString? <span>preferredStyleSheetSet</span>;
readonly attribute DOMStringList <span>styleSheetSets</span>;
void <span title="documentstyle-enablestylesheetsforset">enableStylesheetsForSet</span>(DOMString? <var>name</var>);
};
<span>Document</span> implements <span>DocumentStyle</span>;</pre>
<!-- XXX use Supplemental instead? -->
<p>The
<dfn id="documentstyle-stylesheets"><code>styleSheets</code></dfn>
attribute <em class="ct">must</em> return a <code>StyleSheetList</code>
sequence representing the <span>document style sheets</span>.</p
<p>The
<dfn id="documentstyle-selectedStyleSheetSet"><code>selectedStyleSheetSet</code></dfn>
<em class="ct">must</em>, on getting, run these steps:</p>
<ol>
<li><p>If there is a single <span>enabled style sheet set</span> and no
other <span>document style sheets</span> with a non-empty
<span>style sheet title</span> have the
<span>style sheet disabled flag</span> set to false return the
<span>style sheet set name</span> of the
<span>enabled style sheet set</span> and terminate this set of
steps.</p></li>
<li><p>Otherwise, if <span title="style sheet">style sheets</span> from
different <span title="style sheet set">style sheet sets</span> have
their <span>style sheet disabled flag</span> set to false return
null and terminate this set of steps.</p></li>
<li>
<p>Otherwise, return the empty string.</p>
<p class="note">At this point either all
<span title="style sheet">style sheets</span> with a non-empty
<span>style sheet title</span> have the
<span>style sheet disabled flag</span> set to true or there are no such
<span title="style sheet">style sheets</span>.</p>
</li>
</ol>
<p>On setting the <code>selectedStyleSheetSet</code> attribute these steps
<em class="ct">must</em> be run:</p>
<ol>
<li><p>If the value is null terminate this set of steps.</p></li>
<li><p>Otherwise, <span>select a style sheet set</span> with as name the
value passed.</p></li>
</ol>
<p>From the DOM's perspective, all views have the same
<code>selectedStyleSheetSet</code>. If a user agent supports multiple
views with different selected alternative style sheets, then this
attribute (and the <code>StyleSheet</code> interface's
<code>disabled</code> attribute) <em class="ct">must</em> return and set
the value for the default view.</p>
<!-- XXX clean up once we get rid of views -->
<p>The
<dfn id="documentstyle-lastStyleSheetSet"><code>lastStyleSheetSet</code></dfn>
attribute <em class="ct">must</em> return the
<span>last style sheet set name</span>.</p>
<p class="note">This attribute is initially null.</p>
<p>The
<dfn id="documentstyle-preferredStyleSheetSet"><code>preferredStyleSheetSet</code></dfn>