csswg-drafts/css3-namespace/Overview.html at 6e06eab0c9b808adf15e94253c0b5224639dd43c · w3c/csswg-drafts · GitHub

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<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01//EN">

<html lang=en>
 <head><meta content="text/html; charset=utf-8" http-equiv=Content-Type>

  <title>CSS Namespaces Module</title>
  <link href="../default.css" rel=stylesheet type="text/css">
  <link href="http://www.w3.org/StyleSheets/TR/W3C-ED" 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--></p>

   <h1 id=css-namespaces>CSS Namespaces Module</h1>

   <h2 class="no-num no-toc" id=longstatus>Editor's Draft 24 May 2008</h2>

   <dl>
    <dt>This version:</dt>
    <!-- <dd><a href="http://www.w3.org/TR/2008/CR-css3-namespace-20080524/">http://www.w3.org/TR/2008/CR-css3-namespace-20080524/</a></dd> -->

    <dd><a
     href="http://dev.w3.org/csswg/css3-namespace/">http://dev.w3.org/csswg/css3-namespace/</a>


    <dt>Latest version:

    <dd><a
     href="http://www.w3.org/TR/css3-namespace/">http://www.w3.org/TR/css3-namespace/</a>

    <dt>Previous version:

    <dd><a
     href="http://www.w3.org/TR/2008/WD-css3-namespace-20080215/">http://www.w3.org/TR/2008/WD-css3-namespace-20080215/</a>

    <dt>Editors:

    <dd><a href="http://fantasai.inkedblade.net/contact">Elika J. Etemad</a>

    <dd><a href="http://annevankesteren.nl/contact">Anne van Kesteren</a>,
     Opera Software ASA

    <dt>Previous Editors:

    <dd>Peter Linss, Netscape Communications

    <dd>Chris Lilley, W3C
   </dl>
   <!--begin-copyright-->
   <p class=copyright><a
    href="http://www.w3.org/Consortium/Legal/ipr-notice#Copyright"
    rel=license>Copyright</a> &copy; 2008 <a
    href="http://www.w3.org/"><acronym title="World Wide Web
    Consortium">W3C</acronym></a><sup>&reg;</sup> (<a
    href="http://www.csail.mit.edu/"><acronym title="Massachusetts Institute
    of Technology">MIT</acronym></a>, <a
    href="http://www.ercim.org/"><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>This CSS Namespaces module defines the syntax for using namespaces in
   CSS. It defines the <code>@namespace</code> rule for declaring the default
   namespace and binding namespaces to namespace prefixes, and it also
   defines a syntax that other specifications can adopt for using those
   prefixes in namespace-qualified names.

  <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">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 &#8220;css3-namespace&#8221; in the subject, preferably like this:
   &#8220;[<!---->css3-namespace<!---->] <em>&hellip;summary of
   comment&hellip;</em>&#8221;

  <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>For this specification to exit the CR stage, the following conditions
   shall be met:

  <ol>
   <li>
    <p>There must be at least two interoperable implementations. For the
     purposes of this criterion, we define the following terms:</p>

    <dl>
     <dt>interoperable

     <dd>
      <p>passing the respective test case(s) in the <a
       href="http://www.w3.org/Style/CSS/Test/">CSS test suite</a>, or, if
       the implementation is not a Web browser, an equivalent test. Every
       relevant test in the test suite should have an equivalent test created
       if such a user agent (UA) is to be used to claim interoperability. In
       addition if such a UA is to be used to claim interoperability, then
       there must one or more additional UAs which can also pass those
       equivalent tests in the same way for the purpose of interoperability.
       The equivalent tests must be made publicly available for the purposes
       of peer review.</p>

     <dt>implementation

     <dd>
      <p>a user agent which:</p>

      <ol>
       <li>implements the specification.

       <li>is available (i.e. publicly downloadable or available through some
        other public point of sale mechanism). This is the "show me"
        requirement.

       <li>is shipped, or is a "nightly build" (i.e., a development version
        for the next release), but is not experimental (i.e., a version
        specifically designed to pass the test suite and not intended for
        daily usage going forward).
      </ol>
    </dl>

   <li>
    <p>A minimum of another three months of the CR period must elapse. That
     is, this specification will not exit CR before 23 August 2008. When the
     specification exits CR, an implementation report will be published. At
     this point, no such report exists.</p>

   <li>
    <p>The specified technology must not be harmful for accessibility.</p>
  </ol>

  <p>A CSS Namespace <a href="http://www.w3.org/Style/CSS/Test/">Test
   Suite</a> will be developed during the Candidate Recommendation phase of
   this CSS Namespaces specification.

  <p>Comments on and subsequent changes since the last Working Draft are
   listed in the separate <a
   href="http://dev.w3.org/csswg/css3-namespace/issues-2"> Disposition of
   Comments.</a>

  <h2 class="no-num no-toc" id=contents>Table of contents</h2>
  <!--begin-toc-->

  <ul class=toc>
   <li><a href="#intro"><span class=secno>1. </span>Introduction</a>

   <li><a href="#conformance"><span class=secno>2. </span>Conformance</a>
    <ul class=toc>
     <li><a href="#terminology"><span class=secno>2.1 </span>Terminology</a>
    </ul>

   <li><a href="#declaration"><span class=secno>3. </span>Declaring
    namespaces: the <code>@namespace</code> rule</a>
    <ul class=toc>
     <li><a href="#syntax"><span class=secno>3.1 </span>Syntax</a>

     <li><a href="#scope"><span class=secno>3.2 </span>Scope</a>

     <li><a href="#prefixes"><span class=secno>3.3 </span>Declaring
      Prefixes</a>
    </ul>

   <li><a href="#css-qnames"><span class=secno>4. </span>CSS Qualified
    Names</a>

   <li class=no-num><a href="#acknowledgments">Acknowledgments</a>

   <li class=no-num><a href="#references">References</a>
    <ul class=toc>
     <li class=no-num><a href="#normative-references">Normative
      references</a>

     <li class=no-num><a href="#informative-references">Informative
      references</a>
    </ul>
  </ul>
  <!--end-toc-->

  <div>
   <h2 id=intro><span class=secno>1. </span>Introduction</h2>

   <p><em>This section is non-normative.</em></p>

   <p>This CSS Namespaces module defines syntax for using namespaces in CSS.
    It defines the <code>@namespace</code> rule for declaring a default
    namespace and for binding namespaces to namespace prefixes. It also
    defines a syntax for using those prefixes to represent
    namespace-qualified names. It does not define where such names are valid
    or what they mean: that depends on their context and is defined by a host
    language, such as Selectors (<a href="#SELECT"
    rel=biblioentry>[SELECT]<!--{{SELECT}}--></a>), that references the
    syntax defined in the CSS Namespaces module.</p>

   <p>Note that a CSS client that does not support this module will (if it
    properly conforms to <a
    href="http://www.w3.org/TR/CSS21/syndata.html#parsing-errors">CSS's
    forward-compatible parsing rules</a>) ignore all <code>@namespace</code>
    rules, as well as all style rules that make use of namespace qualified
    names. The syntax of delimiting namespace prefixes in CSS was
    deliberately chosen so that these CSS clients would ignore the style
    rules rather than possibly match them incorrectly.</p>
  </div>

  <div>
   <h2 id=conformance><span class=secno>2. </span>Conformance</h2>

   <p>A document or implementation cannot conform to CSS Namespaces alone,
    but can claim conformance to CSS Namespaces if it satisfies the
    conformance requirements in this specification when implementing CSS or
    another host language that normatively references this specification.</p>

   <p>Conformance to CSS Namespaces is defined for two classes:</p>

   <dl>
    <dt><dfn id=style>style sheet</dfn>

    <dd>A <a href="http://www.w3.org/TR/CSS21/conform.html#style-sheet">CSS
     style sheet</a> (or a complete unit of another host language that
     normatively references CSS Namespaces).

    <dt><dfn id=interpreter>interpreter</dfn>

    <dd>Someone or something that interprets the semantics of a style sheet.
     (CSS <a href="http://www.w3.org/TR/CSS21/conform.html#user-agent">user
     agents</a> fall under this category.)
   </dl>

   <p>The conformance requirements are expressed with a combination of
    descriptive assertions and RFC 2119 terminology. 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 RFC 2119. However, for
    readability, these words do not appear in all uppercase letters in this
    specification. All of the text of this specification is normative except
    sections explicitly marked as non-normative, examples, and notes. <a
    href="#RFC2119" rel=biblioentry>[RFC2119]<!--{{!RFC2119}}--></a></p>

   <p>Examples in this specification are introduced with the words "for
    example" or are set apart from the normative text with
    <code>class="example"</code>, like this:</p>

   <div class=example>
    <p>This is an example of an informative example.</p>
   </div>

   <p>Informative notes begin with the word "Note" and are set apart from the
    normative text with <code>class="note"</code>, like this:</p>

   <p class=note>Note, this is an informative note.</p>

   <h3 id=terminology><span class=secno>2.1 </span>Terminology</h3>

   <p>Besides terms introduced by this specification, CSS Namespaces uses the
    terminology defined in Namespaces in XML 1.0. <a href="#XML-NAMES"
    rel=biblioentry>[XML-NAMES]<!--{{!XML-NAMES}}--></a> However, the syntax
    defined here is not restricted to representing XML element and attribute
    names and may represent other kinds of namespaces as defined by the host
    language.</p>

   <p>In CSS Namespaces a namespace name consisting of the empty string is
    taken to represent the null namespace or lack of a namespace.</p>

   <div class=example>
    <p>For example, given the namespace declarations:</p>

    <pre>@namespace empty "";
<!--  -->@namespace "";</pre>

    <p>The <a href="http://www.w3.org/TR/css3-selectors/#type-selectors">type
     selectors</a> <code>elem</code>, <code>|elem</code>, and
     <code>empty|elem</code> are equivalent.</p>
   </div>
  </div>

  <div>
   <h2 id=declaration><span class=secno>3. </span>Declaring namespaces: the
    <code>@namespace</code> rule</h2>

   <p>The <code>@namespace</code> <a
    href="http://www.w3.org/TR/CSS21/syndata.html#at-rules">at-rule</a>
    declares a namespace prefix and associates it with a given namespace name
    (a string). This namespace prefix can then be used in namespace-qualified
    names such as the <a href="#css-qnames">CSS qualified names</a> defined
    below.</p>

   <div class=example>
    <pre>@namespace "http://www.w3.org/1999/xhtml";
<!--  -->@namespace svg "http://www.w3.org/2000/svg";</pre>

    <p>The first rule declares a default namespace
     <code>http://www.w3.org/1999/xhtml</code> to be applied to names that
     have no explicit namespace component.</p>

    <p>The second rule declares a namespace prefix <code>svg</code> that is
     used to apply the namespace <code>http://www.w3.org/2000/svg</code>
     where the <code>svg</code> namespace prefix is used.</p>
   </div>

   <p id=expanded-name-match>In CSS Namespaces, as in Namespaces in XML 1.0,
    the prefix is merely a syntactic construct; it is the <em><dfn
    id=expanded-name>expanded name</dfn></em> (the tuple of local name and
    namespace name) that is significant. Thus the actual prefixes used in a
    CSS style sheet, and whether they are defaulted or not, are independent
    of the namespace prefixes used in the markup and whether these are
    defaulted or not.</p>

   <div class=example>
    <p>For example, given the following XML document:</p>

    <pre><!--
   -->&lt;qml:elem xmlns:qml="http://example.com/q-markup">&lt;/qml:elem><!--
 --></pre>

    <p>and the following <code>@namespace</code> declarations at the
     beginning of a CSS file:</p>

    <pre><!--
    -->@namespace Q "http://example.com/q-markup";
<!---->@namespace lq "http://example.com/q-markup";<!--
 --></pre>

    <p>The selectors <code>Q|elem</code> and <code>lq|elem</code> in that CSS
     file would both match the element <code>&lt;qml:elem&gt;</code>. (The
     selector <code>qml|elem</code> would be invalid.)</p>
   </div>

   <h3 id=syntax><span class=secno>3.1 </span>Syntax</h3>

   <p>The syntax for the <code>@namespace</code> rule is as follows (using
    the notation from the <a
    href="http://www.w3.org/TR/CSS21/grammar.html">Grammar appendix of CSS
    2.1</a> <a href="#CSS21" rel=biblioentry>[CSS21]<!--{{!CSS21}}--></a>):</p>

   <pre><!--
     -->namespace
<!-- -->  : NAMESPACE_SYM S* [namespace_prefix S*]? [STRING|URI] S* ';' S*
<!-- -->  ;
<!-- -->namespace_prefix
<!-- -->  : IDENT
<!-- -->  ;<!--
  --></pre>

   <p>with the new token:</p>

   <pre>@{N}{A}{M}{E}{S}{P}{A}{C}{E} {return NAMESPACE_SYM;}</pre>

   <p>Any <code>@namespace</code> rules must follow all @charset and @import
    rules and precede all other non-ignored at-rules and rule sets in a style
    sheet. For CSS syntax this adds <code>[ namespace [S|CDO|CDC]* ]*<
2ACE
;/code>
    immediately after <code>[ import [S|CDO|CDC]* ]*</code> in the
    <code>stylesheet</code> grammar.</p>

   <p>A syntactically invalid <code>@namespace</code> rule (whether malformed
    or misplaced) must be <a
    href="http://www.w3.org/TR/CSS21/conform.html#ignore">ignored</a>. A CSS
    <a href="http://www.w3.org/TR/CSS21/conform.html#style-sheet">style
    sheet</a> containing an invalid <code>@namespace</code> rule is itself <a
    href="http://www.w3.org/TR/CSS21/conform.html#valid-style-sheet">invalid</a>.</p>

   <p>A URI string parsed from the <code>URI</code> syntax must be treated as
    a literal string: as with the <code>STRING</code> syntax, no URI-specific
    normalization is applied.</p>

   <p>All strings&#8212;including the empty string and strings representing
    invalid URIs&#8212;are valid namespace names in <code>@namespace</code>
    declarations.</p>

   <h3 id=scope><span class=secno>3.2 </span>Scope</h3>

   <p>The namespace prefix is declared only within the style sheet in which
    its <code>@namespace</code> rule appears. It is not declared in any style
    sheets importing or imported by that style sheet, nor in any other style
    sheets applying to the document.</p>

   <h3 id=prefixes><span class=secno>3.3 </span>Declaring Prefixes</h3>

   <p>A <dfn id=namespace>namespace prefix</dfn>, once declared, represents
    the namespace for which it was declared and can be used to indicate the
    namespace of a namespace-qualified name. Namespace prefixes are, <a
    href="http://www.w3.org/TR/CSS21/syndata.html#counter">like CSS counter
    names</a>, case-sensitive.</p>

   <p>If in the namespace declaration the namespace prefix is omitted, then
    the namespace so declared is the default namespace. The <dfn
    id=default>default namespace</dfn> may apply to names that have no
    explicit namespace prefix: modules that employ namespace prefixes must
    define in which contexts the default namespace applies. For example,
    following <a href="#XML-NAMES"
    rel=biblioentry>[XML-NAMES]<!--{{!XML-NAMES}}--></a>, in Selectors <a
    href="#SELECT" rel=biblioentry>[SELECT]<!--{{SELECT}}--></a> the default
    namespace applies to type selectors&#8212;but it does not apply to
    attribute selectors. There is no default value for the default namespace:
    modules that assign unqualified names to the default namespace must
    define how those unqualified names are to be interpreted when no default
    namespace is declared.</p>

   <p class=note>Note that using default namespaces in conjunction with type
    selectors can cause UAs that support default namespaces and UAs that
    don't support default namespaces to interpret selectors differently. See
    <a href="http://www.w3.org/TR/css3-selectors/#downlevel">Namespaces and
    down-level clients</a> in the Selectors module <a href="#SELECT"
    rel=biblioentry>[SELECT]<!--{{SELECT}}--></a> for details.</p>

   <p>If a namespace prefix or default namespace is declared more than once
    only the last declaration shall be used.</p>
  </div>

  <div>
   <h2 id=css-qnames><span class=secno>4. </span>CSS Qualified Names</h2>

   <p>A <dfn id=css-qualified>CSS qualified name</dfn> is a name explicitly
    located within (associated with) a namespace. To form a qualified name in
    CSS syntax, a namespace prefix that has been declared within scope is
    prepended to a local name (such as an element or attribute name),
    separated by a "vertical bar" (<code>|</code>, U+007C). The prefix,
    representing the namespace for which it has been declared, indicates the
    namespace of the local name. The prefix of a qualified name may be
    omitted to indicate that the name belongs to no namespace, i.e. that the
    namespace name part of the expanded name has no value. Some contexts (as
    defined by the host language) may allow the use of an asterisk
    (<code>*</code>, U+002A) as a wildcard prefix to indicate a name in any
    namespace, including no namespace.</p>

   <div class=example>
    <p>Given the namespace declarations:</p>

    <pre>@namespace toto "http://toto.example.org";
<!--  -->@namespace "http://example.com/foo";</pre>

    <p>In a context where the default namespace applies</p>

    <dl>
     <dt><code>toto|A</code>

     <dd>represents the name <code>A</code> in the
      <code>http://toto.example.org</code> namespace.

     <dt><code>|B</code>

     <dd>represents the name <code>B</code> that belongs to no namespace.

     <dt><code>*|C</code>

     <dd>represents the name <code>C</code> in any namespace, including no
      namespace.

     <dt><code>D</code>

     <dd>represents the name <code>D</code> in the
      <code>http://example.com/foo</code> namespace.
    </dl>
   </div>

   <p>The syntax for the portion of a CSS qualified name before the local
    name is given below, both for qualified names that allow wildcard
    prefixes (<code>wqname</code>) and for qualified names that disallow
    wildcard prefixes (<code>qname</code>). (The syntax uses notation from
    the <a href="http://www.w3.org/TR/CSS21/grammar.html">Grammar appendix of
    CSS 2.1</a> <a href="#CSS21"
    rel=biblioentry>[CSS21]<!--{{!CSS21}}--></a>):</p>

   <pre><!--
     -->qname_prefix
<!-- -->  : [namespace_prefix]? '|'
<!-- -->  ;
<!-- -->wqname_prefix
<!-- -->  : namespace_prefix? '|'
<!-- -->  | '*' '|'
<!-- -->  ;<!--
--></pre>

   <p>CSS qualified names can be used in (for example) selectors and property
    values as described in other modules. Those modules must define handling
    of namespace prefixes that have not been properly declared. Such handling
    should treat undeclared namespace prefixes as a parsing error that will
    cause the selector or declaration (etc.) to be considered invalid and, in
    CSS, <a
    href="http://www.w3.org/TR/CSS21/conform.html#ignore">ignored</a>.</p>

   <div class=example>
    <p>For example, the Selectors module <a href="#SELECT"
     rel=biblioentry>[SELECT]<!--{{SELECT}}--></a> defines a type selector
     with an undeclared namespace prefix to be an invalid selector, and CSS
     <a href="#CSS21" rel=biblioentry>[CSS21]<!--{{!CSS21}}--></a> requires
     rule sets with an invalid selector to be completely ignored.</p>
   </div>
  </div>

  <h2 class=no-num id=acknowledgments>Acknowledgments</h2>

  <p>This draft borrows heavily from earlier drafts on CSS namespace support
   by Chris Lilley and by Peter Linss and early (unpublished) drafts on CSS
   and XML by H&aring;kon Lie and Bert Bos, and XML Namespaces and CSS by
   Bert Bos and Steven Pemberton. Many current and former members of the CSS
   Working Group have contributed to this document. Discussions on
   www-style@w3.org and in other places have also contributed ideas to this
   specification. Special thanks goes to L. David Baron, Karl Dubost, Ian
   Hickson, Bj&ouml;ern H&ouml;hrmann, and Lachlan Hunt for their comments.

  <h2 class=no-num id=references>References</h2>

  <h3 class=no-num id=normative-references>Normative references</h3>
  <!--begin-normative-->
  <!-- Sorted by label -->

  <dl class=bibliography>
   <dt style="display: none"><!-- keeps the doc valid if the DL is empty -->
    <!---->

   <dt id=CSS21>[CSS21]

   <dd>Bert Bos; et al. <a
    href="http://www.w3.org/TR/2007/CR-CSS21-20070719"><cite>Cascading Style
    Sheets Level 2 Revision 1 (CSS 2.1) Specification.</cite></a> 19 July
    2007. W3C Candidate Recommendation. (Work in progress.) URL: <a
    href="http://www.w3.org/TR/2007/CR-CSS21-20070719">http://www.w3.org/TR/2007/CR-CSS21-20070719</a>
    </dd>
   <!---->

   <dt id=RFC2119>[RFC2119]

   <dd>S. Bradner. <a href="http://www.ietf.org/rfc/rfc2119.txt"><cite>Key
    words for use in RFCs to Indicate Requirement Levels.</cite></a> Internet
    RFC 2119. URL: <a
    href="http://www.ietf.org/rfc/rfc2119.txt">http://www.ietf.org/rfc/rfc2119.txt</a>
    </dd>
   <!---->

   <dt id=XML-NAMES>[XML-NAMES]

   <dd>Tim Bray; et al. <a
    href="http://www.w3.org/TR/2006/REC-xml-names-20060816"><cite>Namespaces
    in XML 1.0 (Second Edition).</cite></a> 16 August 2006. W3C
    Recommendation. URL: <a
    href="http://www.w3.org/TR/2006/REC-xml-names-20060816">http://www.w3.org/TR/2006/REC-xml-names-20060816</a>
    </dd>
   <!---->
  </dl>
  <!--end-normative-->

  <h3 class=no-num id=informative-references>Informative references</h3>
  <!--begin-informative-->
  <!-- Sorted by label -->

  <dl class=bibliography>
   <dt style="display: none"><!-- keeps the doc valid if the DL is empty -->
    <!---->

   <dt id=SELECT>[SELECT]

   <dd>Daniel Glazman; Tantek &#199;elik; Ian Hickson. <a
    href="http://www.w3.org/TR/2005/WD-css3-selectors-20051215"><cite>Selectors.</cite></a>
    15 December 2005. W3C Working Draft. (Work in progress.) URL: <a
    href="http://www.w3.org/TR/2005/WD-css3-selectors-20051215">http://www.w3.org/TR/2005/WD-css3-selectors-20051215</a>
    </dd>
   <!---->
  </dl>
  <!--end-informative-->
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