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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 }
.example { margin-left:1em; padding-left:1em; border-left:double; color:#222; background:#fcfcfc }
.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: " }
dl.switch { padding-left:2em }
dl.switch > dt { text-indent:-1.5em }
dl.switch > dt:before { content:'\21AA'; padding:0 0.5em 0 0; display:inline-block; width:1em; text-align:right; line-height:0.5em }
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">
<!--logo-->
<h1 id="cssom">CSSOM</h1>
<h2 class="no-num no-toc">[LONGSTATUS] [DATE: 3 August 2002]</h2>
<dl>
<dt>This Version:</dt>
<dd class=dontpublish><a href="http://dev.w3.org/csswg/cssom/">http://dev.w3.org/csswg/cssom/</a>
<dd class=publish><a href="[VERSION]">[VERSION]</a></dd>
<dt class=publish>Latest Version:</dt>
<dd class=publish><a href="[LATEST]">[LATEST]</a></dd>
<dt class=publish>Latest Editor's draft:</dt>
<dd class=publish><a href="http://dev.w3.org/csswg/cssom/">http://dev.w3.org/csswg/cssom/</a></dd>
<dt class=dontpublish>Previous Version:</dt>
<dd class=dontpublish><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>
<!--copyright-->
</div>
<hr class="top">
<h2 class="no-num no-toc" id="abstract">Abstract</h2>
<p>CSSOM defines APIs (including generic parsing and serialization rules)
for Media Queries, Selectors, and of course CSS itself.</p>
<h2 class="no-num no-toc" id="sotd">Status of this Document</h2>
<p><em>This section describes the status of this document at the time of
its publication. Other documents may supersede this document. A list of
current W3C publications and the latest revision of this technical report
can be found in the
<a href="http://www.w3.org/TR/">W3C technical reports index at http://www.w3.org/TR/.</a></em>
<p>This is the [DATE: 3 August 2002] [LONGSTATUS] of CSSOM. Please send
comments to
<a href="mailto:www-style@w3.org?subject=%5Bcssom%5D%20">www-style@w3.org</a>
(<a href="http://lists.w3.org/Archives/Public/www-style/">archived</a>)
with <samp>[cssom]</samp> at the start of the subject line.
<p>This is the [DATE] First Public Working Draft of CSSOM, produced by the
<a href="http://www.w3.org/Style/CSS/members">CSS Working Group</a> (part
of the <a href="http://www.w3.org/Style/">Style Activity</a>).
<!--XXX remove "First Public" after initial publication -->
<p>This document was produced by a group operating under the
<a href="http://www.w3.org/Consortium/Patent-Policy-20040205/">5 February 2004 W3C Patent Policy</a>.
W3C maintains a
<a href="http://www.w3.org/2004/01/pp-impl/32061/status" rel=disclosure>public list of any patent disclosures</a>
made in connection with the deliverables of the group; that page also
includes instructions for disclosing a patent. An individual who has
actual knowledge of a patent which the individual believes contains
<a href="http://www.w3.org/Consortium/Patent-Policy-20040205/#def-essential">Essential Claim(s)</a>
must disclose the information in accordance with
<a href="http://www.w3.org/Consortium/Patent-Policy-20040205/#sec-Disclosure">section 6 of the W3C Patent Policy</a>.</p>
<p>Publication as a Working Draft does not imply endorsement by the W3C
Membership. This is a draft document and may be updated, replaced or
obsoleted by other documents at any time. It is inappropriate to cite this
document as other than work in progress.
<h2 class="no-num no-toc" id="toc">Table of Contents</h2>
<!--toc-->
<h2 id="introduction">Introduction</h2>
<p class="XXX">...</p>
<h3 id="history">History</h3>
<p>Several interfaces from DOM Level 2 Style
<a href="http://lists.w3.org/Archives/Public/www-style/2003Oct/0347.html" title="[CSSOM] CSSValue and related interfaces (message from the CSS WG)">have
been obsoleted</a> because they were 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>Conformance</h2>
<p>All diagrams, examples, and notes in this specification are
non-normative, as are all sections explicitly marked non-normative.
Everything else in this specification is normative.
<p>The key words "MUST", "MUST NOT", "REQUIRED", <!--"SHALL", "SHALL
NOT",--> "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and
"OPTIONAL" in the normative parts of this document are to be
interpreted as described in RFC2119. For readability, these words do
not appear in all uppercase letters in this specification.
<span data-anolis-ref>RFC2119</span>
<p>Requirements phrased in the imperative as part of algorithms
(such as "strip any leading space characters" or "return false and
terminate these steps") are to be interpreted with the meaning of the
key word ("must", "should", "may", etc) used in introducing the
algorithm.
<p>Conformance requirements phrased as algorithms or specific steps
may be implemented in any manner, so long as the end result is
equivalent. (In particular, the algorithms defined in this
specification are intended to be easy to follow, and not intended to
be performant.)
<p id="hardwareLimitations">User agents may impose
implementation-specific limits on otherwise unconstrained inputs,
e.g. to prevent denial of service attacks, to guard against running
out of memory, or to work around platform-specific limitations.
<p>When a method or an attribute is said to call another method or attribute, the user agent must invoke its internal API for that attribute or method so that e.g. the author can't change the behavior by overriding attributes or methods with custom properties or functions in ECMAScript.
<p>Unless otherwise stated, string comparisons are done in a
<span data-anolis-spec=dom>case-sensitive</span> manner.
<h2 id="terminology">Terminology</h2>
<p>Terminology used in this specification is from
<cite>DOM4</cite>,
<cite>HTML</cite>,
<cite>Associating Style Sheets with XML documents</cite>
and
<cite>XML</cite>
<span data-anolis-ref>DOM</span>
<span data-anolis-ref>HTML</span>
<span data-anolis-ref>XMLSS</span>
<span data-anolis-ref>XML</span>
<p class="XXX"><dfn>supported styling language</dfn>
<p>When this specification talks about object
<code title><var>A</var></code> where <code title><var>A</var></code> is actually an interface, it generally means an object implementing interface
<code title><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>
<h3>Common Serializing Idioms</h3>
<p>To <dfn>serialize a character</dfn> means to create a string of
"<code>\</code>" (U+005C), followed by the character.</p>
<p>To <dfn>serialize a character as code point</dfn> means to create a
string of "<code>\</code>" (U+005C), followed by the Unicode code point as
the smallest possible number of hexadecimal digits in the range 0-9 a-f
(U+0030 to U+0039 and U+0061 to U+0066) to represent the code point in
base 16, followed by a space (U+0020).</p>
<p>To <dfn>serialize an identifier</dfn> means to create a string represented
by the concatenation of, for each character of the identifier:</p>
<ul>
<li>If the character is in the range U+0000 to U+001F or U+007F to
U+009F, the character
<span title="serialize a character as code point">escaped as code point</span>.
<li>If the character is the first character and is in the range 0-9
(U+0030 to U+0039), the character
<span title="serialize a character as code point">escaped as code point</span>.
<li>If the character is the second character and is in the range 0-9
(U+0030 to U+0039) and the first character is a "<code>-</code>"
(U+002D), the character
<span title="serialize a character as code point">escaped as code point</span>.</li>
<li>If the character is the second character and is "<code>-</code>"
(U+002D) and the first character is "<code>-</code>" too, the
<span title="serialize a character">escaped</span> character.</li>
<li>If the character is not handled by one of the above rules and is
greater than or equal to U+0080, is "<code>-</code>" (U+002D) or
"<code>_</code>" (U+005F), or is in one of the ranges 0-9 (U+0030 to
U+0039), A-Z (U+0041 to U+005A), or a-z (U+0061 to U+007A), the character
itself.</li>
<li>Otherwise, the <span title="serialize a character">escaped</span>
character.</li>
</ul>
<p>To <dfn>serialize a string</dfn> means to create a string represented
by '<code>"</code>' (U+0022), followed by the result of applying the rules
below to each character of the given string, followed by
'<code>"</code>' (U+0022):</p>
<ul>
<li>If the character is in the range U+0000 to U+001F or U+007F to
U+009F, the character
<span title="serialize a character as code point">escaped as code point</span>.
<li>If the character is '<code>"</code>' (U+0022) or '<code>\</code>'
(U+005C), the <span title="serialize a character">escaped</span> character.</li>
<li>Otherwise, the character itself.</li>
</ul>
<p class="note">"<code>'</code>" (U+0027) is not escaped because strings
are always serialized with '<code>"</code>' (U+0022).</p>
<p>To <dfn>serialize a URL</dfn> means to create a string represented by
"<code title>url(</code>", followed by the
<span title="serialize a string">string escaped</span> value of the given
string, followed by "<code>)</code>".</p>
<p>To <dfn>serialize a comma-separated list</dfn> concatenate all items of
the list in list order while separating them by "<code>,</code>" (U+002C),
followed by a space (U+0020).</p>
<p>To <dfn>serialize a whitespace-separated list</dfn> concatenate all
items of the list in list order while separating them a space (U+0020).</p>
<h2>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>Parsing Media Queries</h3>
<p>To
<dfn id="parse-a-media-query-list">parse a media query list</dfn> for a
given string <var title>s</var> into a media query list 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">A media query that ends up being "ignored" will turn
into "<code title>not all</code>".</p>
<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 media query list</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 class="note">Again, a media query that ends up being "ignored" will
turn into "<code title>not all</code>".</p>
<h3>Serializing Media Queries</h3>
<p>To
<dfn id="serialize-a-media-query-list">serialize a media query list</dfn>
run these steps:</p>
<ol>
<li><p>If the media query list is empty return the empty string and
terminate these steps.</p></li>
<li><p><span title="serialize a media query">Serialize</span> each
media query in the list of media queries, sort them in lexicographical
order, and then
<span title="serialize a comma-separated list">serialize</span> the
list.</p></li>
</ol>
<p>To
<dfn id="serialize-a-media-query">serialize a media query</dfn> let
<var title>s</var> be the empty string, run the steps below, and
finally return <var title>s</var>:</p>
<ol>
<li><p>If the media query is negated append "<code>not</code>", followed
by a space (U+0020), to <var title>s</var>.</p></li>
<li><p>Let <var title>type</var> be the media type of the media query,
<span title="serialize an identifier">escaped</span> and
<span data-anolis-spec=dom>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 title>s</var>,
then return <var title>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
space (U+0020), followed by "<code>and</code>", followed by a space
(U+0020), 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 "<code>(</code>" (U+0028), followed by the media feature
name, <span data-anolis-spec=dom>converted to ASCII lowercase</span>,
to <var title>s</var>.</p></li>
<li><p>If a value is given append a "<code>:</code>" (U+003A), followed
by a space (U+0020), followed by the
<span title="serialize a media feature value">serialized media feature value</span>,
to <var title>s</var>.</p>
<li><p>Append a "<code>)</code>" (U+0029) to
<var title>s</var>.</p></li>
<li><p>If this is not the last media feature append a space (U+0020),
followed by "<code>and</code>", followed by a space (U+0020), to
<var title>s</var>.</p></li>
</ol>
</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>
<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 title>m1</var> and <var title>m2</var> means to
<span title="serialize a media query">serialize</span> them both and
return true if they are a
<span data-anolis-spec=dom>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="dom-MediaList-mediaText">mediaText</span>;
readonly attribute unsigned long <span title="dom-MediaList-length">length</span>;
getter DOMString <span title="dom-MediaList-item">item</span>(unsigned long <var title>index</var>);
void <span title="dom-MediaList-appendMedium">appendMedium</span>(DOMString <var title>medium</var>);
void <span title="dom-MediaList-deleteMedium">deleteMedium</span>(DOMString <var title>medium</var>);
};</pre>
<p>The
<dfn title="dom-MediaList-mediaText"><code>mediaText</code></dfn>
attribute, on getting, must return a
<span title="serialize a media query list">serialization</span> of
the <span>collection of media queries</span>.</p>
<p>On setting the <code title="dom-MediaList-mediaText">mediaText</code>
attribute these steps must 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 media query list">parsing</span> the given
value to the <span>collection of media queries</span>.</p></li>
</ol>
<p>The
<dfn title="dom-MediaList-length"><code>length</code></dfn>
attribute must return the number of media queries in
the <span>collection of media queries</span>.</p>
<p>The
<dfn title="dom-MediaList-item"><code>item(<var title>index</var>)</code></dfn>
method must return the media query in the
<span>collection of media queries</span> given by
<var title>index</var>, or null, if <var title>index</var> is
greater than or equal to the number of media queries in the
<span>collection of media queries</span>.</p>
<!-- XXX need consistency here WebIDL? list of media queries? -->
<p>The
<dfn title="dom-MediaList-appendmedium"><code>appendMedium(<var title>medium</var>)</code></dfn>
method must 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 title="dom-MediaList-deletemedium"><code>deleteMedium(<var title>medium</var>)</code></dfn>
method must 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="dom-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
mainly defines how to serialize them.</p> <!-- XXX ref -->
<!-- XXX ref universal selector etc? some are in <span> some not -->
<h3>Parsing Selectors</h3>
<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 -->
<h3>Serializing Selectors</h3>
<!-- http://dump.testsuite.org/2009/cssom/serializing-selectors.htm -->
<p>To
<dfn id="serialize-a-group-of-selectors">serialize a group of selectors</dfn>
<span title="serialize a selector">serialize</span> each selector in the
group of selectors and then
<span title="serialize a comma-separated list">serialize</span> the
group.</p>
<p>To <dfn id="serialize-a-selector">serialize a selector</dfn> let
<var title>s</var> be the empty string, run the steps below for each
part of the chain of the selector, and finally return
<var title>s</var>:</p>
<ol>
<li><p>If there is only one <span>simple selector</span> in the
<span>sequence of simple selectors</span> which is a
<span>universal selector</span>, append the result of
<span title="serialize a simple selector">serializing</span> the
<span>universal selector</span> to <var title>s</var>.</p></li>
<li><p>Otherwise, for each <span>simple selector</span> in the
<span>sequence of simple selectors</span> that is not a
universal selector of which the <span>namespace prefix</span> maps to
the null namespace (not in a namespace) or of which the
<span>namespace prefix</span> maps to a namespace that is not the
<span>default namespace</span>
<span title="serialize a simple selector">serialize</span> the
<span>simple selector</span> and append the result to
<var title>s</var>.</p></li>
<li><p>If this is not the last part of the chain of the selector append a
space (U+0020), followed by the combinator
"<code>></code>",
"<code>+</code>", or
"<code>~</code>"
as appropriate, followed by another space (U+0020) if the combinator was
not whitespace, to <var title>s</var>.</p></li>
<li><p>If this is the last part of the chain of the selector and there is
a pseudo-element, append "<code>::</code>" followed by the name of the
pseudo-class, to <var title>s</var>.</p></li>
</ol>
<p>To
<dfn id="serialize-a-simple-selector">serialize a simple selector</dfn>
let <var title>s</var> be the empty string, run the steps below, and
finally return <var title>s</var>:</p>
<dl class="switch">
<dt>type selector</dt>
<dt>universal selector</dt>
<dd>
<ol>
<li><p>If the <span>namespace prefix</span> maps to a namespace that is
not the <span>default namespace</span> and is not the
null namespace (not in a namespace) append the
<span title="serialize an identifier">escaped</span>
<span>namespace prefix</span>, followed by a "<code>|</code>" (U+007C)
to <var title>s</var>.</p></li>
<li><p>If the <span>namespace prefix</span> maps to a namespace that is
the null namespace (not in a namespace) append
"<code>|</code>" (U+007C) to <var title>s</var>.</p></li>
<!-- This includes |* -->
<li><p>If this is a type selector append the
<span title="serialize an identifier">escaped</span> element name to
<var title>s</var>.</p>
<li><p>If this is a universal selector append "<code>*</code> (U+002A)
to <var title>s</var>.</p></li>
</ol>
</dd>
<dt>attribute selector</dt>
<dd>
<ol>
<li><p>Append "<code>[</code>" (U+005B) to
<var title>s</var>.</p></li>
<li><p>If the <span>namespace prefix</span> maps to a namespace that is
not the null namespace (not in a namespace) append the
<span title="serialize an identifier">escaped</span>
<span>namespace prefix</span>, followed by a "<code>|</code>" (U+007C)
to <var title>s</var>.</p></li>
<li><p>If the <span>namespace prefix</span> maps to a namespace that is
the null namespace (not in a namespace) append
"<code>|</code>" (U+007C) to <var title>s</var>.</p></li>
<!-- This includes |* -->
<li><p>Append the <span title="serialize an identifier">escaped</span>
attribute name to <var title>s</var>.</p></li>
<li><p>If there is an attribute value specified, append
"<code>=</code>",
"<code>~=</code>",
"<code>|=</code>",
"<code>^=</code>",
"<code>$=</code>", or
"<code>*=</code>"
as appropriate (depending on the type of attribute selector), followed
by the <span title="serialize a string">string escaped</span>
attribute value, to <var title>s</var>.</p></li>
<li><p>Append "<code>]</code>" (U+005D) to
<var title>s</vaR>.</p></li>
</ol>
</dd>
<dt>class selector</dt>
<dd><p>Append a "<code>.</code>" (U+002E), followed by the
<span title="serialize an identifier">escaped</span> class name to
<var title>s</var>.</p></dd>
<dt>ID selector</dt>
<dd><p>Append a "<code>#</code>" (U+0023), followed by the
<span title="serialize an identifier">escaped</span> ID to
<var title>s</var>.</p></dd>
<dt>pseudo-class</dt>
<dd>
<p>If the pseudo-class does not accept arguments append
"<code>:</code>" (U+003A), followed by the name of the pseudo-class, to
<var title>s</var>.</p>
<p>Otherwise, append "<code>:</code>" (U+003A), followed by the name of
the pseudo-class, followed by "<code>(</code>" (U+0028), followed by the
value of the pseudo-class argument determined as per below, followed by
"<code>)</code>" (U+0029), to <var title>s</var>.</p>
<dl class="switch">
<dt><code title>:lang()</code></dt>
<dd><p>The <span title="serialize an identifier">escaped</span>
value.</p></dd>
<dt><code title>:nth-child()</code></dt>
<dt><code title>:nth-last-child()</code></dt>
<dt><code title>:nth-of-type()</code></dt>
<dt><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>
<span title="serialize a CSS component value">serialized</span> as <integer>.</p></li>
<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>" (U+006E).</p></li>
<li><p>If <var title>a</var> is one or minus one let the value be
"<code title>n</code>" (U+006E), followed by
"<code>+</code>" (U+002B) if <var title>b</var> is positive,
followed by <var title>b</var>
<span title="serialize a CSS component value">serialized</span> as <integer>.</p></li>
<li><p>If <var title>b</var> is zero let the value be
<var title>a</var>
<span title="serialize a CSS component value">serialized</span> as <integer>,
followed by "<code title>n</code>" (U+006E).</p></li>
<li><p>Otherwise let the value be
<var title>a</var>
<span title="serialize a CSS component value">serialized</span> as <integer>,
followed by "<code title>n</code>" (U+006E), followed by
"<code>+</code>" (U+002B) if <var title>b</var> is positive,
followed by <var title>b</var>
<span title="serialize a CSS component value">serialized</span> as <integer>.</p></li>
</ol>
</dd>
<dt><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>
</dl>
</dd>
</dl>
<h2>CSS</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 a style sheet as defined by the CSS specification. In the DOM a
<span>style sheet</span> is a <code>CSSStyleSheet</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 literal string "<code>text/css</code>".</p></dd>
<dt><dfn id="style-sheet-location">style sheet location</dfn></dt>
<dd><p>The <span data-anolis-spec=html>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-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-owner-node">style sheet owner 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-owner-css-rule">style sheet owner CSS rule</dfn></dt>
<dd><p>The <span>CSS rule</span> in the <span>style sheet parent</span>
that caused the inclusion of the <span>style sheet</span> or null if
there is no such <span>CSS rule</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 id="style-sheet-disabled-flag">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>
<dt><dfn id="style-sheet-css-rules">style sheet CSS rules</dfn></dt>
<dd><p>The <span title="CSS rule">CSS rules</span> associated with the
<span>style sheet</span>.</p></dd>
</dl>
<p>When you are to <span>create a style sheet</span> the above properties,
with the exception of <span>style sheet type</span> and
<span>style sheet CSS rules</span>, are to be set to
their proper values.</p>
<!-- same-origin restrictions -->
<h4>The <code title>StyleSheet</code> Interface</h4>
<p>The <code>StyleSheet</code> interface represents a base interface that
has no meaning on its own.</p>
<pre class="idl">interface <dfn id="stylesheet">StyleSheet</dfn> {
readonly attribute DOMString <span title="dom-StyleSheet-type">type</span>;
readonly attribute DOMString <span title="dom-StyleSheet-href">href</span>;
readonly attribute Node <span title="dom-StyleSheet-ownerNode">ownerNode</span>;
readonly attribute <span>StyleSheet</span> <span title="dom-StyleSheet-parentStyleSheet">parentStyleSheet</span>;
readonly attribute DOMString <span title="dom-StyleSheet-title">title</span>;
[PutForwards=<span title="dom-MediaList-mediaText">mediaText</span>] readonly attribute <span>MediaList</span> <span title="dom-StyleSheet-media">media</span>;
attribute boolean <span title="dom-StyleSheet-disabled">disabled</span>;
};</pre>
<p>The
<dfn title="dom-StyleSheet-type"><code>type</code></dfn>
attribute must return the
<span>style sheet type</span>.</p>
<p>The
<dfn title="dom-StyleSheet-href"><code>href</code></dfn>
attribute must return the
<span>style sheet location</span>.</p>
<p>The
<dfn title="dom-StyleSheet-ownerNode"><code>ownerNode</code></dfn>
attribute must return the
<span>style sheet owner node</span>.</p>
<p>The
<dfn title="dom-StyleSheet-parentStyleSheet"><code>parentStyleSheet</code></dfn>
attribute must return the
<span>style sheet parent</span>.</p>
<p>The
<dfn title="dom-StyleSheet-title"><code>title</code></dfn>
attribute must return the
<span>style sheet title</span>.</p>
<p>The
<dfn title="dom-StyleSheet-media"><code>media</code></dfn>
attribute must return the
<span>style sheet media</span>.</p>
<p>The
<dfn title="dom-StyleSheet-disabled"><code>disabled</code></dfn>
attribute must, on getting, return the
<span>style sheet disabled flag</span>. On setting, it
must set the <span>style sheet disabled flag</span> to
the given value.</p>
<h4>The <code title>CSSStyleSheet</code> Interface</h4>
<p>The <code>CSSStyleSheet</code> interface represents a
<span>style sheet</span>.</p>
<!--
IE exposes:
owningElement, pages, id, type, href, disabled, cssText, readOnly, title,
parentStyleSheet, imports, rules, media
-->
<pre class="idl">interface <dfn>CSSStyleSheet</dfn> : <span>StyleSheet</span> {
readonly attribute <span>CSSRule</span> <span title="dom-CSSStyleSheet-ownerRule">ownerRule</span>;
readonly attribute <span>CSSRuleList</span> <span title="dom-CSSStyleSheet-cssRules">cssRules</span>;
unsigned long <span title="dom-CSSStyleSheet-insertRule">insertRule</span>(DOMString <var title>rule</var>, unsigned long <var title>index</var>);
void <span title="dom-CSSStyleSheet-deleteRule">deleteRule</span>(unsigned long <var title>index</var>);
};</pre>
<p>The
<dfn title="dom-CSSStyleSheet-ownerRule"><code>ownerRule</code></dfn>
attribute must return the
<span>style sheet owner CSS rule</span>.</p>
<p>The
<dfn title="dom-CSSStyleSheet-cssRules"><code>cssRules</code></dfn>
attribute must return a <code>CSSRuleList</code>
object representing the <span>style sheet CSS rules</span>.</p>
<p class="note">CSS rules that were dropped during parsing can not be
found using APIs described by this specification.</p>
<p>The
<dfn title="dom-CSSStyleSheet-insertRule"><code>insertRule(<var title>rule</var>, <var title>index</var>)</code></dfn>
method must <span>insert a CSS rule</span>
<var title>rule</var> the in CSS rule list returned by
<code title="dom-CSSStyleSheet-cssRules">cssRules</code> at
<var title>index</var>.</p>
<p>The
<dfn title="dom-CSSStyleSheet-deleteRule"><code>deleteRule(<var title>index</var>)</code></dfn>
method must <span>remove a CSS rule</span> from the
CSS rule list returned by
<code title="dom-CSSStyleSheet-cssRules">cssRules</code> at
<var title>index</var>.</p>
<h3>Style Sheet Collections</h3>
<p>Below various new concepts are defined that are associated with each
<code data-anolis-spec=dom>Document</code> object.</p>
<p>Each <code data-anolis-spec=dom>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 data-anolis-spec=dom>Document</code>, in
<span data-anolis-spec=dom title=concept-tree-order>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>