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<!doctype html>
<html lang="en-US">
<head>
<meta charset=utf-8>
<title>CSS Object Model (CSSOM)</title>
<link rel="stylesheet" href="cssom.css">
<link rel="stylesheet" href="http://www.w3.org/StyleSheets/TR/W3C-[STATUS]">
</head>
<body class="draft">
<div class="head">
<!--logo-->
<!-- ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ -->
<!-- ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ -->
<h1 id="cssom">CSS Object Model (CSSOM)</h1>
<!-- ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ -->
<h2 class="no-num no-toc" id="w3c-doctype">[LONGSTATUS] [DATE: 3 August 2002]</h2>
<dl>
<dt>This Version:</dt>
<dd class=dontpublish><a href="http://dvcs.w3.org/hg/csswg/raw-file/tip/cssom/Overview.html">http://dvcs.w3.org/hg/csswg/raw-file/tip/cssom/Overview.html</a></dd>
<dd class=publish><a href="[VERSION]">[VERSION]</a></dd>
<dt class=dontpublish>Participate:</dt>
<dd class=dontpublish><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/">archives</a>)</dd>
<dd class=dontpublish><a href="https://www.w3.org/Bugs/Public/enter_bug.cgi?product=CSS&component=CSSOM">File a bug</a></dd>
<dd class=dontpublish><a href="irc://irc.w3.org/css">IRC: #css on W3C</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://dvcs.w3.org/hg/csswg/raw-file/tip/cssom/Overview.html">http://dvcs.w3.org/hg/csswg/raw-file/tip/cssom/Overview.html</a></dd>
<dt class=dontpublish>Previous Version:</dt>
<dd class=dontpublish><a href="http://www.w3.org/TR/2011/WD-cssom-20110712/">http://www.w3.org/TR/2011/WD-cssom-20110712/</a></dd>
<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>Editors:</dt>
<dd><a href="http://www.w3.org/wiki/User:Gadams">Glenn Adams</a>
(<a href="http://www.cox.com/">Cox Communications, Inc.</a>)
<<a href="mailto:glenn.adams@cox.com">glenn.adams@cox.com</a>></dd>
<dd><a>Shane Stephens</a>
(<a href="http://www.google.com/">Google, Inc.</a>)
<<a href="mailto:shans@google.com">shans@google.com</a>></dd>
<dt>Previous 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>This is a public copy of the editors' draft. It is provided for discussion only and may change at any moment.
Its publication here does not imply endorsement of its contents by W3C or by the CSS Working Group. Don't cite
this document other than as work in progress.</p>
<p class="note">Implementers should note well that this specification is an ongoing effort to sort out
what has been widely implemented and deployed from DOM-2 Style as well as common extensions thereto, some details
of which are currently interoperable and others which are not currently interoperable. As this specification moves
forward, it is hoped that these differences will be resolved and an unambiguous and adequate consensus-based
specification will emerge.</p>
<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 class="dontpublish">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 class="publish">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>
<!-- ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ -->
<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://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="issue"><dfn>supported styling language</dfn>
<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>
<!-- ........................................................................................................................ -->
<!-- ........................................................................................................................ -->
<h3>Common Serializing Idioms</h3>
<p>To <dfn>escape a character</dfn> means to create a string of
"<code>\</code>" (U+005C), followed by the character.</p>
<p>To <dfn>escape 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="escape a character as code point">escaped as code point</span>.</li>
<li>If the character is the first character and is in the range 0-9
(U+0030 to U+0039), the character
<span title="escape a character as code point">escaped as code point</span>.</li>
<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="escape 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="escape 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="escape 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="escape a character as code point">escaped as code point</span>.</li>
<li>If the character is '<code>"</code>' (U+0022) or '<code>\</code>'
(U+005C), the <span title="escape 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>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>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>not all</code>".</p>
<p>To
<dfn id="parse-a-media-query">parse a media query</dfn> for a given string
<var>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>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>s</var> be the empty string, run the steps below, and
finally return <var>s</var>:</p>
<ol>
<li><p>If the media query is negated append "<code>not</code>", followed
by a space (U+0020), to <var>s</var>.</p></li>
<li><p>Let <var>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>type</var>, to <var>s</var>,
then return <var>s</var> and terminate this algorithm.</p></li>
<li><p>If <var>type</var> is not "<code>all</code>" or if the
media query is negated append <var>type</var>, followed by a
space (U+0020), followed by "<code>and</code>", followed by a space
(U+0020), to <var>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>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>s</var>.</p></li>
<li><p>Append a "<code>)</code>" (U+0029) to
<var>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>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="issue">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>v</var> locate <var>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>width</code>
<td>...
<tr>
<td><code>height</code>
<td>...
<tr>
<td><code>device-width</code>
<td>...
<tr>
<td><code>device-height</code>
<td>...
<tr>
<td><code>orientation</code>
<td>
<p>If the value is `<code>portrait</code>`: "<code>portrait</code>".</p>
<p>If the value is `<code>landscape</code>`: "<code>landscape</code>".</p>
<tr>
<td><code>aspect-ratio</code>
<td>...
<tr>
<td><code>device-aspect-ratio</code>
<td>...
<tr>
<td><code>color</code>
<td>...
<tr>
<td><code>color-index</code>
<td>...
<tr>
<td><code>monochrome</code>
<td>...
<tr>
<td><code>resolution</code>
<td>...
<tr>
<td><code>scan</code>
<td>
<p>If the value is `<code>progressive</code>`: "<code>progressive</code>".</p>
<p>If the value is `<code>interlace</code>`: "<code>interlace</code>".</p>
<tr>
<td><code>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="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>MediaList</code> Interface</h3>
<!--{@idl(MediaList)}-->
<!-- ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ -->
<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>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>s</var> be the empty string, run the steps below for each
part of the chain of the selector, and finally return
<var>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>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>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>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>s</var>.</p></li>
</ol>
<p>To
<dfn id="serialize-a-simple-selector">serialize a simple selector</dfn>
let <var>s</var> be the empty string, run the steps below, and
finally return <var>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>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>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>s</var>.</p></li>
<li><p>If this is a universal selector append "<code>*</code>" (U+002A)
to <var>s</var>.</p></li>
</ol>
</dd>
<dt>attribute selector</dt>
<dd>
<ol>
<li><p>Append "<code>[</code>" (U+005B) to
<var>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>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>s</var>.</p></li>
<!-- This includes |* -->
<li><p>Append the <span title="serialize an identifier">escaped</span>
attribute name to <var>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>s</var>.</p></li>
<li><p>Append "<code>]</code>" (U+005D) to
<var>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>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>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>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>s</var>.</p>
<dl class="switch">
<dt><code>:lang()</code></dt>
<dd><p>The <span title="serialize an identifier">escaped</span>
value.</p></dd>
<dt><code>:nth-child()</code></dt>
<dt><code>:nth-last-child()</code></dt>
<dt><code>:nth-of-type()</code></dt>
<dt><code>:nth-last-of-type()</code></dt>
<dd>
<ol>
<li><p>If the value is odd let the value be
"<code>2n+1</code>".</p></li>
<li><p>If the value is even let the value be
"<code>2n</code>".</p></li>
<li><p>If <var>a</var> is zero let the value be
<var>b</var>
<span title="serialize a CSS component value">serialized</span> as <integer>.</p></li>
<li><p>If <var>a</var> is one or minus one and
<var>b</var> is zero let the value be
"<code>n</code>" (U+006E).</p></li>
<li><p>If <var>a</var> is one or minus one let the value be
"<code>n</code>" (U+006E), followed by
"<code>+</code>" (U+002B) if <var>b</var> is positive,
followed by <var>b</var>
<span title="serialize a CSS component value">serialized</span> as <integer>.</p></li>
<li><p>If <var>b</var> is zero let the value be
<var>a</var>
<span title="serialize a CSS component value">serialized</span> as <integer>,
followed by "<code>n</code>" (U+006E).</p></li>
<li><p>Otherwise let the value be
<var>a</var>
<span title="serialize a CSS component value">serialized</span> as <integer>,
followed by "<code>n</code>" (U+006E), followed by
"<code>+</code>" (U+002B) if <var>b</var> is positive,
followed by <var>b</var>
<span title="serialize a CSS component value">serialized</span> as <integer>.</p></li>
</ol>
</dd>
<dt><code>: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> 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 set or unset. Unset 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 set or unset. Unset by default.</p>
<p class="note">Even when unset it does not necessarily mean that the
<span>style sheet</span> is actually used for rendering.</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>StyleSheet</code> Interface</h4>
<!--{@idl(StyleSheet)}-->
<!-- ........................................................................................................................ -->
<h4>The <code>CSSStyleSheet</code> Interface</h4>
<!--{@idl(CSSStyleSheet)}-->
<!-- ........................................................................................................................ -->
<!-- ........................................................................................................................ -->
<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 set, 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 unset, 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 unset the
<span>style sheet disabled flag</span> and terminate these steps:
<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 data-anolis-spec=dom>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 data-anolis-spec=dom>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>.</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 unset.</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> unset.</p>
<p>To <dfn id="enable-a-style-sheet-set">enable a style sheet set</dfn>
with name <var>name</var>, run these steps:</p>
<ol>
<li><p>If <var>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> and terminate these steps.</li>
<li><p>Unset 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
<span data-anolis-spec=dom>case-sensitive</span> match for
<var>name</var> and set it 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>name</var>, run these steps:</p>
<ol>
<li><p><span>Enable a style sheet set</span> with name
<var>name</var>.</p></li>
<li><p>Set <span>last style sheet set name</span> to
<var>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 title="style sheet">style sheets</span> need to have their
<span>style sheet disabled flag</span> unset. 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>name</var>, run these steps:</p>
<ol>
<li><p>Let <var>current</var> be the <span>preferred style sheet set name</span>.</p></li>
<li><p>Set <span>preferred style sheet set name</span> to
<var>name</var>.</p></li>
<li><p>If <var>name</var> is not a
<span data-anolis-spec=dom>case-sensitive</span> match for
<var>current</var> and
<span>last style sheet set name</span> is null
<span>enable a style sheet set</span> with name
<var>name</var>.</p></li>
</ol>
<!-- XXX ought to define "applied"
thoughts:
depends on disabled flag, alternate flag, media queries, sheesh
-->
<!-- ........................................................................................................................ -->
<h4>The HTTP <code>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 must
<span>change the preferred style sheet set name</span> with name being the
value of the header.</p>
<!-- ........................................................................................................................ -->
<h4>The <code>StyleSheetList</code> Sequence</h4>
<!--{@idl(StyleSheetList)}-->
<!-- ........................................................................................................................ -->
<h4>Extensions to the <code>Document</code> Interface</h4>
<!--{@idl(Document)}-->
<!-- ........................................................................................................................ -->
<h4>Interaction with the User Interface</h4>
<p>The user interface of Web browsers that support style sheets
should list the style sheet titles given in the
<code title="dom-Document-styleSheetSets">styleSheetSets</code> list,
showing the
<code title="dom-Document-selectedStyleSheetSet">selectedStyleSheetSet</code>
as the selected style sheet set, leaving none selected if it is
null or the empty string, and selecting an extra option
"Basic Page Style" (or similar) if it is the empty string and the
<code title="dom-Document-preferredStyleSheetSet">preferredStyleSheetSet</code>
is the empty string as well.</p>
<p>Selecting a style sheet from this list should
use the <span>select a style sheet set</span> set of steps. This
(by definition) affects the
<code title="dom-Document-lastStyleSheetSet">lastStyleSheetSet</code>
attribute.</p>
<h5>Persisting the selected style sheet set</h5>
<p>If a user agent persist the selected style sheet set, they should use
the value of the
<code title="dom-Document-selectedStyleSheetSet">selectedStyleSheetSet</code>
attribute, or if that is null, the
<code title="dom-Document-lastStyleSheetSet">lastStyleSheetSet</code>
attribute, when leaving the page (or at some other time) to determine the
set name to store. If that is null then the style sheet set should not be
persisted.</p>
<p>When re-setting the style sheet set to the persisted value (which can