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<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01//EN"
"http://www.w3.org/TR/html4/strict.dtd">
<html lang=en>
<head>
<title>Selectors Level 4</title>
<link href=default.css rel=stylesheet type="text/css">
<link href="http://www.w3.org/StyleSheets/TR/W3C-ED.css" rel=stylesheet
type="text/css">
<body>
<div class=head> <!--begin-logo-->
<p><a href="http://www.w3.org/"><img alt=W3C height=48
src="http://www.w3.org/Icons/w3c_home" width=72></a> <!--end-logo-->
<h1 id=title>Selectors Level 4</h1>
<h2 class="no-num no-toc" id=longstatus-date>Editor's Draft 12 August 2011</h2>
<dl>
<dt>This version:
<dd> <!-- <a href="http://www.w3.org/TR/2011/ED-selectors4-20110812/">
http://www.w3.org/TR/2011/WD-selectors4-20110812</a> -->
<a href="http://dev.w3.org/csswg/selectors4">
http://dev.w3.org/csswg/selectors4</a>
<dt>Latest version:
<dd><a href="http://www.w3.org/TR/selectors">
http://www.w3.org/TR/selectors</a>
<dt>Previous version:
<dd><a href="http://www.w3.org/TR/css3-selectors/">
http://www.w3.org/TR/css3-selectors/</a>
<dt><a name=editors-list></a>Editors:
<dd class=vcard><a class="url fn"
href="http://fantasai.inkedblade.net/contact">Elika J. Etemad</a>
(Invited Expert)
<dt>Previous Editors:
<dd class=vcard><a class="url fn" href="http://www.tantek.com/"
lang=tr>Tantek Çelik</a> (Microsoft)
<dd class=vcard><span class=fn>Daniel Glazman</span> (Disruptive
Innovations SARL)
<dd class=vcard><span class=fn>Ian Hickson</span> (Opera Softare ASA)
<dd class=vcard><span class=fn>Peter Linss</span> (Netscape/AOL)
<dd class=vcard><span class=fn>John Williams</span> (Quark, Inc.)
</dl>
<!--begin-copyright-->
<p class=copyright><a
href="http://www.w3.org/Consortium/Legal/ipr-notice#Copyright"
rel=license>Copyright</a> © 2011 <a
href="http://www.w3.org/"><acronym title="World Wide Web
Consortium">W3C</acronym></a><sup>®</sup> (<a
href="http://www.csail.mit.edu/"><acronym title="Massachusetts Institute
of Technology">MIT</acronym></a>, <a href="http://www.ercim.eu/"><acronym
title="European Research Consortium for Informatics and
Mathematics">ERCIM</acronym></a>, <a
href="http://www.keio.ac.jp/">Keio</a>), All Rights Reserved. W3C <a
href="http://www.w3.org/Consortium/Legal/ipr-notice#Legal_Disclaimer">liability</a>,
<a
href="http://www.w3.org/Consortium/Legal/ipr-notice#W3C_Trademarks">trademark</a>
and <a
href="http://www.w3.org/Consortium/Legal/copyright-documents">document
use</a> rules apply.</p>
<!--end-copyright-->
<hr title="Separator for header">
</div>
<h2 class="no-num no-toc" id=abstract> Abstract</h2>
<p><em>Selectors</em> are patterns that match against elements in a tree,
and as such form one of several technologies that can be used to select
nodes in an XML document. Selectors have been optimized for use with HTML
and XML, and are designed to be usable in performance-critical code. They
are a core component of <acronym title="Cascading Style
Sheets">CSS</acronym> (Cascading Style Sheets), which uses Selectors to
bind style properties to elements in the document.
<p>Selectors Level 4 describes the selectors that already exist in
[[!CSS3SELECT]], and further introduces new selectors for CSS and other
languages that may need them.
<h2 class="no-num no-toc" id=status>Status of this Document</h2>
<!--begin-status-->
<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. Don't cite this document
other than as work in progress.
<p>The (<a
href="http://lists.w3.org/Archives/Public/www-style/">archived</a>) public
mailing list <a
href="mailto:www-style@w3.org?Subject=%5Bselectors4%5D%20PUT%20SUBJECT%20HERE">
www-style@w3.org</a> (see <a
href="http://www.w3.org/Mail/Request">instructions</a>) is preferred for
discussion of this specification. When sending e-mail, please put the text
“selectors4” in the subject, preferably like this:
“[<!---->selectors4<!---->] <em>…summary of
comment…</em>”
<p>This document was produced by the <a href="/Style/CSS/members">CSS
Working Group</a> (part of the <a href="/Style/">Style Activity</a>).
<p>This document was produced by a group operating under the <a
href="/Consortium/Patent-Policy-20040205/">5 February 2004 W3C Patent
Policy</a>. W3C maintains a <a href="/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="/Consortium/Patent-Policy-20040205/#def-essential">Essential
Claim(s)</a> must disclose the information in accordance with <a
href="/Consortium/Patent-Policy-20040205/#sec-Disclosure">section 6 of the
W3C Patent Policy</a>.</p>
<!--end-status-->
<p><strong>This module is an early-stage Working Draft. If you are looking
for a stable Selectors specification, use <a
href="http://www.w3.org/TR/css3-selectors/">Selectors 3</a>.</strong> Read
the <a href="http://www.w3.org/TR/CSS/">CSS Snapshot</a> for an overview
of the CSS development process.
<h2 class="no-num no-toc" id=contents>Table of Contents</h2>
<!--begin-toc-->
<ul class=toc>
<li><a href="#context"><span class=secno>1. </span> Introduction</a>
<ul class=toc>
<li><a href="#placement"><span class=secno>1.1. </span>Module
Interactions</a>
</ul>
<li><a href="#overview"><span class=secno>2. </span> Selectors
Overview</a>
<li><a href="#syntax"><span class=secno>3. </span> Selector Syntax and
Structure</a>
<ul class=toc>
<li><a href="#structure"><span class=secno>3.1. </span> Structure and
Terminology</a>
<li><a href="#subject"><span class=secno>3.2. </span> Determining the
Subject of a Selector</a>
<li><a href="#pseudo-classes"><span class=secno>3.3. </span>
Pseudo-classes</a>
<li><a href="#pseudo-elements"><span class=secno>3.4.
</span>Pseudo-elements</a>
<li><a href="#case-sensitive"><span class=secno>3.5. </span> Characters
and case sensitivity</a>
<li><a href="#namespaces"><span class=secno>3.6. </span> Namespaces</a>
<li><a href="#invalid"><span class=secno>3.7. </span> Invalid Selectors
and Error Handling</a>
</ul>
<li><a href="#logical-combination"><span class=secno>4. </span> Logical
Combinations</a>
<ul class=toc>
<li><a href="#grouping"><span class=secno>4.1. </span> Selector
Lists</a>
<li><a href="#matches"><span class=secno>4.2. </span> The Matches-Any
Pseudo-class: ‘<code class=css>:matches()</code>’</a>
<li><a href="#negation"><span class=secno>4.3. </span> The Negation
Pseudo-class: ‘<code class=css>:not()</code>’</a>
</ul>
<li><a href="#elemental-selectors"><span class=secno>5. </span> Elemental
selectors</a>
<ul class=toc>
<li><a href="#type-selectors"><span class=secno>5.1. </span> Type
selector</a>
<ul class=toc>
<li><a href="#typenmsp"><span class=secno>5.1.1. </span> Type
selectors and namespaces</a>
</ul>
<li><a href="#universal-selector"><span class=secno>5.2. </span>
Universal selector </a>
<ul class=toc>
<li><a href="#univnmsp"><span class=secno>5.2.1. </span> Universal
selector and namespaces</a>
</ul>
</ul>
<li><a href="#attribute-selectors"><span class=secno>6. </span> Attribute
selectors</a>
<ul class=toc>
<li><a href="#attribute-representation"><span class=secno>6.1. </span>
Attribute presence and value selectors</a>
<li><a href="#attribute-substrings"><span class=secno>6.2. </span>
Substring matching attribute selectors</a>
<li><a href="#attribute-case"><span class=secno>6.3. </span>
Case-sensitivity</a>
<li><a href="#attrnmsp"><span class=secno>6.4. </span> Attribute
selectors and namespaces</a>
<li><a href="#def-values"><span class=secno>6.5. </span> Default
attribute values in DTDs</a>
<li><a href="#class-html"><span class=secno>6.6. </span> Class
selectors</a>
<li><a href="#id-selectors"><span class=secno>6.7. </span> ID
selectors</a>
</ul>
<li><a href="#location"><span class=secno>7. </span> Location
Pseudo-classes</a>
<ul class=toc>
<li><a href="#any-link-pseudo"><span class=secno>7.1. </span> The
hyperlink pseudo-class: ‘<code
class=css>:any-link</code>’</a>
<li><a href="#link"><span class=secno>7.2. </span> The link history
pseudo-classes: ‘<code class=css>:link</code>’ and
‘<code class=css>:visited</code>’</a>
<li><a href="#here-pseudo"><span class=secno>7.3. </span> The local link
pseudo-class ‘<code class=css>:local-link</code>’</a>
<li><a href="#target-pseudo"><span class=secno>7.4. </span> The target
pseudo-class ‘<code class=css>:target</code>’</a>
<li><a href="#scope-pseudo"><span class=secno>7.5. </span> The
contextual reference element pseudo-class ‘<code
class=css>:scope</code>’</a>
</ul>
<li><a href="#useraction-pseudos"><span class=secno>8. </span> User Action
Pseudo-classes</a>
<ul class=toc>
<li><a href="#hover-pseudo"><span class=secno>8.1. </span> The pointer
hover pseudo-class ‘<code class=css>:hover</code>’</a>
<li><a href="#active-pseudo"><span class=secno>8.2. </span> The
activation pseudo-class ‘<code
class=css>:active</code>’</a>
<li><a href="#active-pseudo"><span class=secno>8.3. </span> The input
focus pseudo-class ‘<code class=css>:focus</code>’</a>
</ul>
<li><a href="#time-pseudo"><span class=secno>9. </span> Time-linear
Presentation Pseudo-classes</a>
<ul class=toc>
<li><a href="#current-pseudo"><span class=secno>9.1. </span> The
current-element pseudo-class ‘<code
class=css>:current</code>’</a>
<li><a href="#past-pseudo"><span class=secno>9.2. </span> The
past-element pseudo-class ‘<code
class=css>:past</code>’</a>
<li><a href="#future-pseudo"><span class=secno>9.3. </span> The
future-element pseudo-class ‘<code
class=css>:future</code>’</a>
</ul>
<li><a href="#linguistic-pseudos"><span class=secno>10. </span> Linguistic
Pseudo-classes</a>
<ul class=toc>
<li><a href="#dir-pseudo"><span class=secno>10.1. </span> The
directionality pseudo-class ‘<code
class=css>:dir()</code>’</a>
<li><a href="#lang-pseudo"><span class=secno>10.2. </span> The language
pseudo-class ‘<code class=css>:lang</code>’</a>
</ul>
<li><a href="#ui-states-pseudos"><span class=secno>11. </span> The UI
states pseudo-classes</a>
<ul class=toc>
<li><a href="#enableddisabled"><span class=secno>11.1. </span> The
‘<code class=css>:enabled</code>’ and ‘<code
class=css>:disabled</code>’ pseudo-classes</a>
<li><a href="#checked"><span class=secno>11.2. </span> The
selected-option pseudo-class ‘<code
class=css>:checked</code>’</a>
<li><a href="#indeterminate"><span class=secno>11.3. </span> The
indeterminate-value pseudo-class ‘<code
class=css>:indeterminate</code>’</a>
<li><a href="#default-pseudo"><span class=secno>11.4. </span> The
default option pseudo-class ‘<code
class=css>:default</code>’</a>
<li><a href="#validity-pseudos"><span class=secno>11.5. </span> The
validity pseudo-classes ‘<code class=css>:valid</code>’ and
‘<code class=css>:invalid</code>’</a>
<li><a href="#range-pseudos"><span class=secno>11.6. </span> The range
pseudo-classes ‘<code class=css>:in-range</code>’ and
‘<code class=css>:out-of-range</code>’</a>
<li><a href="#opt-pseudos"><span class=secno>11.7. </span> The
optionality pseudo-classes ‘<code
class=css>:required</code>’ and ‘<code
class=css>:optional</code>’</a>
<li><a href="#rw-pseudos"><span class=secno>11.8. </span> The
alterability pseudo-classes ‘<code
class=css>:read-only</code>’ and ‘<code
class=css>:read-write</code>’</a>
</ul>
<li><a href="#structural-pseudos"><span class=secno>12. </span>
Tree-Structural pseudo-classes</a>
<ul class=toc>
<li><a href="#root-pseudo"><span class=secno>12.1. </span> ‘<code
class=css>:root</code>’ pseudo-class</a>
<li><a href="#nth-child-pseudo"><span class=secno>12.2. </span>
‘<code class=css>:nth-child()</code>’ pseudo-class</a>
<li><a href="#nth-last-child-pseudo"><span class=secno>12.3. </span>
‘<code class=css>:nth-last-child()</code>’ pseudo-class</a>
<li><a href="#nth-of-type-pseudo"><span class=secno>12.4. </span>
‘<code class=css>:nth-of-type()</code>’ pseudo-class</a>
<li><a href="#nth-last-of-type-pseudo"><span class=secno>12.5. </span>
‘<code class=css>:nth-last-of-type()</code>’
pseudo-class</a>
<li><a href="#nth-match"><span class=secno>12.6. </span> ‘<code
class=css>:nth-match()</code>’ pseudo-class</a>
<li><a href="#nth-last-match"><span class=secno>12.7. </span>
‘<code class=css>:nth-last-match()</code>’ pseudo-class</a>
<li><a href="#first-child-pseudo"><span class=secno>12.8. </span>
‘<code class=css>:first-child</code>’ pseudo-class</a>
<li><a href="#last-child-pseudo"><span class=secno>12.9. </span>
‘<code class=css>:last-child</code>’ pseudo-class</a>
<li><a href="#first-of-type-pseudo"><span class=secno>12.10. </span>
‘<code class=css>:first-of-type</code>’ pseudo-class</a>
<li><a href="#last-of-type-pseudo"><span class=secno>12.11. </span>
‘<code class=css>:last-of-type</code>’ pseudo-class</a>
<li><a href="#only-child-pseudo"><span class=secno>12.12. </span>
‘<code class=css>:only-child</code>’ pseudo-class</a>
<li><a href="#only-of-type-pseudo"><span class=secno>12.13. </span>
‘<code class=css>:only-of-type</code>’ pseudo-class</a>
<li><a href="#empty-pseudo"><span class=secno>12.14. </span>
‘<code class=css>:empty</code>’ pseudo-class</a>
</ul>
<li><a href="#table-pseudos"><span class=secno>13. </span> Grid-Structural
Selectors</a>
<ul class=toc>
<li><a href="#nth-column-pseudo"><span class=secno>13.1. </span>
‘<code class=css>:nth-column()</code>’ pseudo-class</a>
<li><a href="#nth-last-column-pseudo"><span class=secno>13.2. </span>
‘<code class=css>:nth-last-column()</code>’
pseudo-class</a>
<li><a href="#column-pseudo"><span class=secno>13.3. </span>
‘<code class=css>:column()</code>’ pseudo-class</a>
</ul>
<li><a href="#combinators"><span class=secno>14. </span> Combinators</a>
<ul class=toc>
<li><a href="#descendant-combinators"><span class=secno>14.1. </span>
Descendant combinator</a>
<li><a href="#child-combinators"><span class=secno>14.2. </span> Child
combinators</a>
<li><a href="#adjacent-sibling-combinators"><span class=secno>14.3.
</span> Adjacent sibling combinator</a>
<li><a href="#general-sibling-combinators"><span class=secno>14.4.
</span> General sibling combinator</a>
<li><a href="#idref-combinator"><span class=secno>14.5. </span>
Reference combinators</a>
</ul>
<li><a href="#formal-syntax"><span class=secno>15. </span> Formal
Syntax</a>
<ul class=toc>
<li><a href="#grammar"><span class=secno>15.1. </span> Grammar</a>
<li><a href="#lex"><span class=secno>15.2. </span> Lexical scanner</a>
</ul>
<li><a href="#profiling"><span class=secno>16. </span>Profiles</a>
<li><a href="#conformance"><span class=secno>17. </span> Conformance</a>
<ul class=toc>
<li><a href="#conventions"><span class=secno>17.1. </span>Document
Conventions</a>
<li><a href="#conformance-classes"><span class=secno>17.2. </span>
Conformance Classes</a>
<li><a href="#partial"><span class=secno>17.3. </span> Partial
Implementations</a>
<li><a href="#experimental"><span class=secno>17.4. </span> Experimental
Implementations</a>
</ul>
<li><a href="#acknowledgements"><span class=secno>18. </span>
Acknowledgements</a>
<li><a href="#references"><span class=secno>19. </span> References</a>
<ul class=toc>
<li><a href="#normative-references"><span class=secno>19.1. </span>
Normative References</a>
<li><a href="#informative-references"><span class=secno>19.2. </span>
Informative References</a>
</ul>
</ul>
<!--end-toc-->
<h2 id=context><span class=secno>1. </span> Introduction</h2>
<p><em>This section is not normative.</em>
<p>Selectors define the following function for elements in a tree
structure:
<pre>expression ∗ element → boolean</pre>
<p>That is, given an element and a selector, this specification defines
whether that element matches the selector.
<p>These expressions can also be used, for instance, to select a set of
elements, or a single element from a set of elements, by evaluating the
expression across all the elements in a subtree. <acronym title="Simple
Tree Transformation Sheets">STTS</acronym> (Simple Tree Transformation
Sheets), a language for transforming XML trees, uses this mechanism. <a
href="#STTS3" rel=biblioentry>[STTS3]<!--{{STTS3}}--></a>
<p>Selectors Levels 1, 2, and 3 are defined as the subsets of selector
functionality defined in the <a
href="http://www.w3.org/TR/REC-CSS1">CSS1</a>, <a
href="http://www.w3.org/TR/CSS21/">CSS2.1</a>, and <a
href="http://www.w3.org/TR/css3-selectors/">Selectors Level 3</a>
specifications, respectively. This module defines Selectors Level 4.
<h3 id=placement><span class=secno>1.1. </span>Module Interactions</h3>
<p>This module replaces the definitions for, and extends the set of
selectors defined for CSS in [[CSS3SELECT]] and <a href="#CSS21"
rel=biblioentry>[CSS21]<!--{{CSS21}}--></a>.
<p>Pseudo-element selectors, which define abstract elements in a rendering
tree, are not part of this specification: their generic syntax is
described here, but, due to their close integration with the rendering
model and irrelevance to other uses such as DOM queries, they will be
defined in other modules.
<h2 id=overview><span class=secno>2. </span> Selectors Overview</h2>
<p><em>This section is non-normative, as it merely summarizes the following
sections.</em>
<p>A Selector represents a structure. This structure can be used as a
condition (e.g. in a CSS rule) that determines which elements a selector
matches in the document tree, or as a flat description of the HTML or XML
fragment corresponding to that structure.
<p>Selectors may range from simple element names to rich contextual
representations.
<p>The following table summarizes the Selector syntax:
<table class="selectorsReview data">
<thead>
<tr>
<th class=pattern>Pattern
<th class=meaning>Meaning
<th class=described>Described in section
<th class=origin>First defined in CSS level
<tbody>
<tr>
<td class=pattern>*
<td class=meaning>any element
<td class=described><a href="#universal-selector">Universal selector</a>
<td class=origin>2
<tr>
<td class=pattern>E
<td class=meaning>an element of type E
<td class=described><a href="#type-selectors">Type selector</a>
<td class=origin>1
<tr>
<td class=pattern>E[foo]
<td class=meaning>an E element with a "foo" attribute
<td class=described><a href="#attribute-selectors">Attribute
selectors</a>
<td class=origin>2
<tr>
<td class=pattern>E[foo="bar"]
<td class=meaning>an E element whose "foo" attribute value is exactly
equal to "bar"
<td class=described><a href="#attribute-selectors">Attribute
selectors</a>
<td class=origin>2
<tr>
<td class=pattern>E[foo~="bar"]
<td class=meaning>an E element whose "foo" attribute value is a list of
whitespace-separated values, one of which is exactly equal to "bar"
<td class=described><a href="#attribute-selectors">Attribute
selectors</a>
<td class=origin>2
<tr>
<td class=pattern>E[foo^="bar"]
<td class=meaning>an E element whose "foo" attribute value begins
exactly with the string "bar"
<td class=described><a href="#attribute-selectors">Attribute
selectors</a>
<td class=origin>3
<tr>
<td class=pattern>E[foo$="bar"]
<td class=meaning>an E element whose "foo" attribute value ends exactly
with the string "bar"
<td class=described><a href="#attribute-selectors">Attribute
selectors</a>
<td class=origin>3
<tr>
<td class=pattern>E[foo*="bar"]
<td class=meaning>an E element whose "foo" attribute value contains the
substring "bar"
<td class=described><a href="#attribute-selectors">Attribute
selectors</a>
<td class=origin>3
<tr>
<td class=pattern>E[foo|="en"]
<td class=meaning>an E element whose "foo" attribute has a
hyphen-separated list of values beginning (from the left) with "en"
<td class=described><a href="#attribute-selectors">Attribute
selectors</a>
<td class=origin>2
<tr>
<td class=pattern>E:root
<td class=meaning>an E element, root of the document
<td class=described><a href="#structural-pseudos">Structural
pseudo-classes</a>
<td class=origin>3
<tr>
<td class=pattern>E:nth-child(n)
<td class=meaning>an E element, the n-th child of its parent
<td class=described><a href="#structural-pseudos">Structural
pseudo-classes</a>
<td class=origin>3
<tr>
<td class=pattern>E:nth-last-child(n)
<td class=meaning>an E element, the n-th child of its parent, counting
from the last one
<td class=described><a href="#structural-pseudos">Structural
pseudo-classes</a>
<td class=origin>3
<tr>
<td class=pattern>E:nth-of-type(n)
<td class=meaning>an E element, the n-th sibling of its type
<td class=described><a href="#structural-pseudos">Structural
pseudo-classes</a>
<td class=origin>3
<tr>
<td class=pattern>E:nth-last-of-type(n)
<td class=meaning>an E element, the n-th sibling of its type, counting
from the last one
<td class=described><a href="#structural-pseudos">Structural
pseudo-classes</a>
<td class=origin>3
<tr>
<td class=pattern>E:first-child
<td class=meaning>an E element, first child of its parent
<td class=described><a href="#structural-pseudos">Structural
pseudo-classes</a>
<td class=origin>2
<tr>
<td class=pattern>E:last-child
<td class=meaning>an E element, last child of its parent
<td class=described><a href="#structural-pseudos">Structural
pseudo-classes</a>
<td class=origin>3
<tr>
<td class=pattern>E:first-of-type
<td class=meaning>an E element, first sibling of its type
<td class=described><a href="#structural-pseudos">Structural
pseudo-classes</a>
<td class=origin>3
<tr>
<td class=pattern>E:last-of-type
<td class=meaning>an E element, last sibling of its type
<td class=described><a href="#structural-pseudos">Structural
pseudo-classes</a>
<td class=origin>3
<tr>
<td class=pattern>E:only-child
<td class=meaning>an E element, only child of its parent
<td class=described><a href="#structural-pseudos">Structural
pseudo-classes</a>
<td class=origin>3
<tr>
<td class=pattern>E:only-of-type
<td class=meaning>an E element, only sibling of its type
<td class=described><a href="#structural-pseudos">Structural
pseudo-classes</a>
<td class=origin>3
<tr>
<td class=pattern>E:empty
<td class=meaning>an E element that has no children (including text
nodes)
<td class=described><a href="#structural-pseudos">Structural
pseudo-classes</a>
<td class=origin>3
<tr>
<td class=pattern>E:link<br>
E:visited
<td class=meaning>an E element being the source anchor of a hyperlink of
which the target is not yet visited (:link) or already visited
(:visited)
<td class=described><a href="#link">The link pseudo-classes</a>
<td class=origin>1
<tr>
<td class=pattern>E:active<br>
E:hover<br>
E:focus
<td class=meaning>an E element during certain user actions
<td class=described><a href="#useraction-pseudos">The user action
pseudo-classes</a>
<td class=origin>1 and 2
<tr>
<td class=pattern>E:target
<td class=meaning>an E element being the target of the referring URI
<td class=described><a href="#target-pseudo">The target pseudo-class</a>
<td class=origin>3
<tr>
<td class=pattern>E:lang(fr)
<td class=meaning>an element of type E in language "fr" (the document
language specifies how language is determined)
<td class=described><a href="#lang-pseudo">The :lang() pseudo-class</a>
<td class=origin>2
<tr>
<td class=pattern>E:enabled<br>
E:disabled
<td class=meaning>a user interface element E which is enabled or
disabled
<td class=described><a href="#UIstates">The UI element states
pseudo-classes</a>
<td class=origin>3
<tr>
<td class=pattern>E:checked
<td class=meaning>a user interface element E which is checked/selected
(for instance a radio-button or checkbox)
<td class=described><a href="#UIstates">The UI element states
pseudo-classes</a>
<td class=origin>3
<tr>
<td class=pattern>E:indeterminate
<td class=meaning>a user interface element E which is in an
indeterminate state (neither checked nor unchecked)
<td class=described><a href="#UIstates">The UI element states
pseudo-classes</a>
<td class=origin>3
<tr>
<td class=pattern>E.warning
<td class=meaning>an E element whose class is "warning" (the document
language specifies how class is determined).
<td class=described><a href="#class-html">Class selectors</a>
<td class=origin>1
<tr>
<td class=pattern>E#myid
<td class=meaning>an E element with ID equal to "myid".
<td class=described><a href="#id-selectors">ID selectors</a>
<td class=origin>1
<tr>
<td class=pattern>E:not(s)
<td class=meaning>an E element that does not match simple selector s
<td class=described><a href="#negation">Negation pseudo-class</a>
<td class=origin>3
<tr>
<td class=pattern>E F
<td class=meaning>an F element descendant of an E element
<td class=described><a href="#descendant-combinators">Descendant
combinator</a>
<td class=origin>1
<tr>
<td class=pattern>E > F
<td class=meaning>an F element child of an E element
<td class=described><a href="#child-combinators">Child combinator</a>
<td class=origin>2
<tr>
<td class=pattern>E + F
<td class=meaning>an F element immediately preceded by an E element
<td class=described><a href="#adjacent-sibling-combinators">Adjacent
sibling combinator</a>
<td class=origin>2
<tr>
<td class=pattern>E ~ F
<td class=meaning>an F element preceded by an E element
<td class=described><a href="#general-sibling-combinators">General
sibling combinator</a>
<td class=origin>3
</table>
<p>The meaning of each selector is derived from the table above by
prepending "matches" to the contents of each cell in the "Meaning" column.
<h2 id=syntax><span class=secno>3. </span> Selector Syntax and Structure</h2>
<h3 id=structure><span class=secno>3.1. </span> Structure and Terminology</h3>
<p>The term <dfn id=selector>selector</dfn> can refer to a <i>simple
selector</i>, <i>compound selector</i>, <a
href="#complex-selector"><i>complex selector</i></a>, or <a
href="#selector-list"><i>selector list</i></a>.
<p>A <dfn id=complex-selector>complex selector</dfn> is a chain of one or
more <a href="#compound">compound selectors</a> separated by <a
href="#combinators">combinators</a>.
<p>A <dfn id=compound-selector><a name=compound>compound selector</a></dfn>
is a chain of <a href="#simple">simple selectors</a> that are not
separated by a <a href="#combinators">combinator</a>. It always begins
with a <a href="#type-selectors">type selector</a> or a (possibly implied)
<a href="#universal-selector">universal selector</a>. No other type
selector or universal selector is allowed in the sequence.
<p>A <dfn id=simple-selector><a name=simple></a><a href="#simple">simple
selector</a></dfn> is either a <a href="#type-selectors">type
selector</a>, <a href="#universal-selector">universal selector</a>, <a
href="#attribute-selectors">attribute selector</a>, <a
href="#class-html">class selector</a>, <a href="#id-selectors">ID
selector</a>, or <a href="#pseudo-classes">pseudo-class</a>.
<p><dfn id=combinator>Combinators</dfn> are punctuation that represent a
particular kind of relationship between the compound selectors on either
side. Combinators in Selectors level 4 include: whitespace,
"greater-than sign" (U+003E, <code>></code>), "plus
sign" (U+002B, <code>+</code>) and "tilde" (U+007E,
<code>~</code>). <a href="#whitespace">White space</a> may appear between
a combinator and the simple selectors around it.
<p>An empty selector, containing no compound selector, is an <a
href="#invalid">invalid selector</a>.
<h3 id=subject><span class=secno>3.2. </span> Determining the Subject of a
Selector</h3>
<p>The elements of a document tree that are represented by a selector are
the <dfn id=subjects>subjects</dfn> of the selector.
<p>By default, the subjects of a selector are the elements represented by
the last compound selector in the selector. Thus a selector consisting of
a single compound selector represents any element satisfying its
requirements. Prepending another compound selector and a combinator to a
sequence imposes additional matching constraints, so the subjects of the
selector are always a subset of the elements represented by the last
compound selector.
<p>The subject of the selector can be explicitly identified by prepending a
dollar sign ($) to one of the compound selectors in a selector. Although
the element structure that the selector represents is the same with or
without the dollar sign, indicating the subject in this way can change
which compound selector represents the subject in that structure.
<div class=example>
<p>For example, the following selector represents a list item
<code>LI</code> unique child of an ordered list <code>OL</code>:
<pre>OL > LI:only-child</pre>
<p>However the following one represents an ordered list <code>OL</code>
having a unique child, that child being a <code>LI</code>:
<pre>$OL > LI:only-child</pre>
<p>The structures represented by these two selectors are the same, but the
subjects of the selectors are not.
</div>
<h3 id=pseudo-classes><span class=secno>3.3. </span> Pseudo-classes</h3>
<p>The pseudo-class concept is introduced to permit selection based on
information that lies outside of the document tree or that cannot be
expressed using the other simple selectors.
<p>A pseudo-class always consists of a "colon" (<code>:</code>)
followed by the name of the pseudo-class and, for functional
pseudo-classes, by a value between parentheses. White space is optionally
allowed between the parentheses and the argument, but not between the
pseudo-class name and the parentheses.
<p>Pseudo-classes are allowed in all compound selectors contained in a
selector. Pseudo-classes are allowed anywhere in a compound selector after
the leading type selector or (possibly omitted) universal selector.
Pseudo-class names are case-insensitive. Some pseudo-classes are mutually
exclusive (such that a compound selector containing them, while valid,
will never match anything), while others can apply simultaneously to the
same element. Pseudo-classes may be dynamic, in the sense that an element
can acquire or lose a pseudo-class while a user interacts with the
document.
<p>Dynamic pseudo-classes classify elements on characteristics other than
their name, attributes, or content, in principle characteristics that
cannot be deduced from the document tree.
<p>Dynamic pseudo-classes do not appear in the document source or document
tree.
<h3 id=pseudo-elements><span class=secno>3.4. </span>Pseudo-elements</h3>
<p>Pseudo-elements create abstractions about the document tree beyond those
specified by the document language. For instance, document languages do
not offer mechanisms to access the first letter or first line of an
element's content. Pseudo-elements allow authors to refer to this
otherwise inaccessible information. Pseudo-elements may also provide
authors a way to refer to content that does not exist in the source
document (e.g., the <code>::before</code> and <code>::after</code>
pseudo-elements give access to generated content in CSS <a href="#CSS21"
rel=biblioentry>[CSS21]<!--{{CSS21}}--></a>).
<p>A pseudo-element is made of two colons (<code>::</code>) followed by the
name of the pseudo-element.
<p>This <code>::</code> notation was chosen in order to establish a
discrimination between pseudo-classes (which subclass existing elements)
and pseudo-elements (which are elements not represented in the document
tree). However, for compatibility with existing style sheets, user agents
must also accept the previous one-colon notation for pseudo-elements
introduced in CSS levels 1 and 2 (namely, <code>:first-line</code>,