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1 <html>
2 <head>
5 <script>
9 // Try to force real results
21 });
26 });
31 });
36 });
39 };
40 </script>
41 </head>
42 <body>
44 <p><a href="http://www.w3.org/"><img height=48 alt=W3C src="http://www.w3.org/Icons/w3c_home" width=72></a>
50 <dl>
52 <dt>This version:
57 <dt>Latest version:
60 http://www.w3.org/TR/css3-selectors</a>
62 <dt>Previous version:
71 <dd class="vcard"><a lang="tr" class="url fn" href="http://www.tantek.com/">Tantek Çelik</a> (Invited Expert)
82 </dl>
93 <a
95 <a
97 <a
99 use</a> rules apply.
103 </div>
108 tree. Selectors have been optimized for use with HTML and XML, and
109 are designed to be usable in performance-critical code.</p>
112 Style Sheets) is a language for describing the rendering of <acronym
115 screen, on paper, in speech, etc. CSS uses Selectors for binding
116 style properties to elements in the document. This document
117 describes extensions to the selectors defined in CSS level 2. These
118 extended selectors will be used by CSS level 3.
124 <p>That is, given an element and a selector, this specification
125 defines whether that element matches the selector.</p>
127 <p>These expressions can also be used, for instance, to select a set
128 of elements, or a single element from a set of elements, by
129 evaluating the expression across all the elements in a
136 <p><em>This section describes the status of this document at the
137 time of its publication. Other documents may supersede this
138 document. A list of current W3C publications and the latest revision
139 of this technical report can be found in the <a
141 http://www.w3.org/TR/.</a></em></p>
149 <p>The CSS Working Group doesn't expect that all implementations of
150 CSS3 will have to implement all selectors. Instead, there will
151 probably be a small number of variants of CSS3, called profiles. For
152 example, it may be that only a profile for interactive user agents
153 will include all of the selectors.</p>
158 document is a revision of the <a
161 implementation feedback received in the past few years. It is
162 expected that this last call will proceed straight to Proposed
163 Recommendation stage since it is believed that interoperability will
164 be demonstrable.</p>
166 <p>All persons are encouraged to review and implement this
167 specification and return comments to the (<a
169 public mailing list <a
172 Members can also send comments directly to the CSS Working
173 Group.
176 <p>This is still a draft document and may be updated, replaced, or
177 obsoleted by other documents at any time. It is inappropriate to
182 The English version of this specification is the only normative
183 version.
191 <ul>
195 </ul>
205 </ul>
207 <ul>
209 </ul>
212 <li class="tocline4"><a href="#attribute-representation">6.3.1. Representation of attributes and attributes values</a>
216 </ul>
226 <ul>
239 </ul>
241 </ul>
242 </li>
243 </ul>
245 <ul>
250 </ul>
257 <li class="tocline4"><a href="#adjacent-sibling-combinators">8.3.1. Adjacent sibling combinator</a>
258 <li class="tocline4"><a href="#general-sibling-combinators">8.3.2. General sibling combinator</a></li>
259 </ul>
260 </li>
261 </ul>
267 </ul>
274 </ul>
276 </div>
282 <p>Some features of this specification are specific to CSS, or have
283 particular limitations or rules specific to CSS. In this
284 specification, these have been described in terms of CSS2.1. <a
289 <p>All of the text of this specification is normative except
290 examples, notes, and sections explicitly marked as
291 non-normative.</p>
297 <p>The main differences between the selectors in CSS2 and those in
298 Selectors are:
300 <ul>
302 <li>the list of basic definitions (selector, group of selectors,
303 simple selector, etc.) has been changed; in particular, what was
304 referred to in CSS2 as a simple selector is now called a sequence
305 of simple selectors, and the term "simple selector" is now used for
306 the components of this sequence</li>
308 <li>an optional namespace component is now allowed in type element
309 selectors, the universal selector and attribute selectors</li>
313 <li>new simple selectors including substring matching attribute
314 selectors, and new pseudo-classes</li>
317 for pseudo-elements</li>
321 <li>profiles to be added to specifications integrating Selectors
322 and defining the set of selectors which is actually supported by
323 each specification</li>
325 <li>Selectors are now a CSS3 Module and an independent
326 specification; other specifications can now refer to this document
327 independently of CSS</li>
331 </ul>
335 <p><em>This section is non-normative, as it merely summarizes the
336 following sections.</em></p>
338 <p>A Selector represents a structure. This structure can be used as a
339 condition (e.g. in a CSS rule) that determines which elements a
340 selector matches in the document tree, or as a flat description of the
341 HTML or XML fragment corresponding to that structure.</p>
343 <p>Selectors may range from simple element names to rich contextual
344 representations.</p>
349 <thead>
350 <tr>
355 <tbody>
356 <tr>
361 selector</a></td>
363 <tr>
369 <tr>
374 selectors</a></td>
376 <tr>
382 selectors</a></td>
384 <tr>
390 selectors</a></td>
392 <tr>
398 selectors</a></td>
400 <tr>
406 selectors</a></td>
408 <tr>
414 selectors</a></td>
416 <tr>
422 selectors</a></td>
424 <tr>
429 pseudo-classes</a></td>
431 <tr>
436 pseudo-classes</a></td>
438 <tr>
441 from the last one</td>
444 pseudo-classes</a></td>
446 <tr>
451 pseudo-classes</a></td>
453 <tr>
456 from the last one</td>
459 pseudo-classes</a></td>
461 <tr>
466 pseudo-classes</a></td>
468 <tr>
473 pseudo-classes</a></td>
475 <tr>
480 pseudo-classes</a></td>
482 <tr>
487 pseudo-classes</a></td>
489 <tr>
494 pseudo-classes</a></td>
496 <tr>
501 pseudo-classes</a></td>
503 <tr>
506 nodes)</td>
509 pseudo-classes</a></td>
511 <tr>
514 which the target is not yet visited (:link) or already visited
515 (:visited)</td>
518 pseudo-classes</a></td>
520 <tr>
525 action pseudo-classes</a></td>
527 <tr>
532 pseudo-class</a></td>
534 <tr>
537 language specifies how language is determined)</td>
540 pseudo-class</a></td>
542 <tr>
545 disabled</td>
548 pseudo-classes</a></td>
550 <tr>
556 pseudo-classes</a></td>
558 <tr>
563 pseudo-element</a></td>
565 <tr>
570 pseudo-element</a></td>
572 <tr>
575 selected/highlighted by the user</td>
578 fragments pseudo-elements</a></td>
580 <tr>
585 pseudo-element</a></td>
587 <tr>
592 pseudo-element</a></td>
594 <tr>
600 selectors</a></td>
602 <tr>
607 selectors</a></td>
609 <tr>
614 pseudo-class</a></td>
616 <tr>
621 combinator</a></td>
623 <tr>
628 combinator</a></td>
630 <tr>
636 <tr>
643 <p>The meaning of each selector is derived from the table above by
645 column.</p>
649 <p>The case sensitivity of document language element names, attribute
650 names, and attribute values in selectors depends on the document
651 language. For example, in HTML, element names are case-insensitive,
652 but in XML, they are case-sensitive.</p>
665 selector or universal selector is allowed in the sequence.</p>
677 sequence of simple selectors.</p>
682 space may appear between a combinator and the simple selectors around
687 never part of white space.</p>
689 <p>The elements of a document tree that are represented by a selector
691 selector consisting of a single sequence of simple selectors
692 represents any element satisfying its requirements. Prepending another
693 sequence of simple selectors and a combinator to a sequence imposes
694 additional matching constraints, so the subjects of a selector are
695 always a subset of the elements represented by the last sequence of
696 simple selectors.</p>
698 <p>An empty selector, containing no sequence of simple selectors and
704 <p>When several selectors share the same declarations, they may be
709 <p>In this example, we condense three rules with identical
710 declarations into one. Thus,</p>
711 <pre>h1 { font-family: sans-serif }
712 h2 { font-family: sans-serif }
713 h3 { font-family: sans-serif }</pre>
716 </div>
719 because all the selectors are valid selectors. If just one of these
720 selectors were invalid, the entire group of selectors would be
721 invalid. This would invalidate the rule for all three heading
722 elements, whereas in the former case only one of the three individual
723 heading rules would be invalidated.</p>
731 element type. A type selector represents an instance of the element
732 type in the document tree.</p>
738 </div>
745 that has been previously declared may be prepended to the element name
749 <p>The namespace component may be left empty to indicate that the
750 selector is only to represent elements with no declared namespace.</p>
752 <p>An asterisk may be used for the namespace prefix, indicating that
753 the selector represents elements in any namespace (including elements
754 with no namespace).</p>
756 <p>Element type selectors that have no namespace component (no
757 namespace separator), represent elements without regard to the
758 element's namespace (equivalent to "<code>*|</code>") unless a default
759 namespace has been declared. If a default namespace has been declared,
760 the selector will represent only elements in the default
761 namespace.</p>
763 <p>A type selector containing a namespace prefix that has not been
765 The mechanism for declaring a namespace prefix is left up to the
766 language implementing Selectors. In CSS, such a mechanism is defined
767 in the General Syntax module.</p>
769 <p>In a namespace-aware client, element type selectors will only match
770 against the <a
772 of the element's <a
775 behaviors in down-level clients.</p>
779 <dl>
783 <dd>elements with name E in any namespace, including those without any
784 declared namespace</dd>
788 <dd>if no default namespace has been specified, this is equivalent to *|E.
789 Otherwise it is equivalent to ns|E where ns is the default namespace.</dd>
790 </dl>
795 <pre>@namespace foo url(http://www.example.com);
796 foo|h1 { color: blue }
797 foo|* { color: yellow }
798 |h1 { color: red }
799 *|h1 { color: green }
800 h1 { color: green }</pre>
805 <p>The second rule will match all elements in the
809 any declared namespace.</p>
812 namespace (including those without any declared namespace).</p>
814 <p>The last rule is equivalent to the fourth rule because no default
815 namespace has been defined.</p>
817 </div>
823 type. It represents any single element in the document tree in any
824 namespace (including those without any declared namespace) if no
825 default namespace has been specified. If a default namespace has been
829 <p>If the universal selector is not the only component of a sequence
834 <ul>
838 </ul>
839 </div>
843 omitted.</p>
847 <p>The universal selector allows an optional namespace component. It
848 is used as follows:</p>
850 <dl>
858 <dd>if no default namespace has been specified, this is equivalent to *|*.
859 Otherwise it is equivalent to ns|* where ns is the default namespace.</dd>
860 </dl>
862 <p>A universal selector containing a namespace prefix that has not
864 selector. The mechanism for declaring a namespace prefix is left up
865 to the language implementing Selectors. In CSS, such a mechanism is
866 defined in the General Syntax module.</p>
871 <p>Selectors allow the representation of an element's attributes. When
872 a selector is used as an expression to match against an element,
873 attribute selectors must be considered to match an element if that
874 element has an attribute that matches the attribute represented by the
875 attribute selector.</p>
878 selectors</a></h4>
882 <dl>
885 the attribute.</dd>
894 spaces).</dd>
904 </dl>
906 <p>Attribute values must be identifiers or strings. The
907 case-sensitivity of attribute names and values in selectors depends on
908 the document language.</p>
916 value:</p>
920 <p>In the following example, the selector represents a
926 <p>Multiple attribute selectors can be used to represent several
927 attributes of an element, or several conditions on the same
936 and "~=". The first selector will represent, for example, the value
956 <p>Similarly, the following selectors represents a
960 <pre>DIALOGUE[character=romeo]
961 DIALOGUE[character=juliet]</pre>
963 </div>
966 selectors</h4>
968 <p>Three additional attribute selectors are provided for matching
969 substrings in the value of an attribute:</p>
971 <dl>
981 </dl>
983 <p>Attribute values must be identifiers or strings. The
984 case-sensitivity of attribute names in selectors depends on the
985 document language.</p>
990 image:</p>
998 </div>
1002 <p>Attribute selectors allow an optional namespace component to the
1003 attribute name. A namespace prefix that has been previously declared
1004 may be prepended to the attribute name separated by the namespace
1006 the Namespaces in the XML recommendation, default namespaces do not
1007 apply to attributes, therefore attribute selectors without a namespace
1008 component apply only to attributes that have no declared namespace
1009 (equivalent to "<code>|attr</code>"). An asterisk may be used for the
1010 namespace prefix indicating that the selector is to match all
1011 attribute names without regard to the attribute's namespace.
1013 <p>An attribute selector with an attribute name containing a namespace
1014 prefix that has not been previously declared is an <a
1016 a namespace prefix is left up to the language implementing Selectors.
1017 In CSS, such a mechanism is defined in the General Syntax module.
1022 [foo|att=val] { color: blue }
1023 [*|att] { color: yellow }
1024 [|att] { color: green }
1025 [att] { color: green }</pre>
1027 <p>The first rule will match only elements with the attribute
1031 <p>The second rule will match only elements with the attribute
1033 (including no declared namespace).</p>
1035 <p>The last two rules are equivalent and will match only elements
1037 declared to be in a namespace.</p>
1039 </div>
1043 <p>Attribute selectors represent explicitly set attribute values in
1044 the document tree. Default attribute values may be defined in a DTD or
1045 elsewhere, but cannot always be selected by attribute
1046 selectors. Selectors should be designed so that they work even if the
1047 default values are not included in the document tree.</p>
1056 knowledge of that namespace to treat default attribute values as if
1057 they were present in the document. (For example, an XHTML UA is not
1058 required to use its built-in knowledge of the XHTML DTD.)</p>
1061 choose to ignore external subsets.</p>
1073 <pre>EXAMPLE[notation=decimal] { /*... default property settings ...*/ }
1074 EXAMPLE[notation=octal] { /*... other settings...*/ }</pre>
1077 is set by default, i.e. not set explicitly. To catch all cases, the
1078 attribute selector for the default value must be dropped:</p>
1080 <pre>EXAMPLE { /*... default property settings ...*/ }
1081 EXAMPLE[notation=octal] { /*... other settings...*/ }</pre>
1084 more specific than the tag
1085 selector alone, the style declarations in the second rule will override
1086 those in the first for elements that have a "notation" attribute value
1087 of "octal". Care has to be taken that all property declarations that
1088 are to apply only to the default case are overridden in the non-default
1089 cases' style rules.</p>
1091 </div>
1099 the same meaning. The attribute value must immediately follow the
1102 <p>UAs may apply selectors using the period (.) notation in XML
1103 documents if the UA has namespace-specific knowledge that allows it to
1105 respective namespace. One such example of namespace-specific knowledge
1106 is the prose in the specification for a particular namespace (e.g. SVG
1117 <p>We can assign style information to all elements with
1126 <p>The following assigns style only to H1 elements with
1131 <p>Given these rules, the first H1 instance below would not have
1132 green text, while the second would:</p>
1137 </div>
1147 has been assigned a list of <a
1157 </div>
1160 power to the "class" attribute, authors could conceivably design their
1161 own "document language" based on elements with almost no associated
1162 presentation (such as DIV and SPAN in HTML) and assigning style
1163 information through the "class" attribute. Authors should avoid this
1164 practice since the structural elements of a document language often
1165 have recognized and accepted meanings and author-defined classes may
1166 not.</p>
1169 class attributes, their values must be concatenated with spaces
1170 between the values before searching for the class. As of this time the
1171 working group is not aware of any manner in which this situation can
1172 be reached, however, so this behavior is explicitly non-normative in
1173 this specification.</p>
1177 <p>Document languages may contain attributes that are declared to be
1178 of type ID. What makes attributes of type ID special is that no two
1179 such attributes can have the same value in a document, regardless of
1180 the type of the elements that carry them; whatever the document
1181 language, an ID typed attribute can be used to uniquely identify its
1182 element. In HTML all ID attributes are named "id"; XML applications
1183 may name ID attributes differently, but the same restriction
1184 applies.</p>
1186 <p>An ID-typed attribute of a document language allows authors to
1187 assign an identifier to one element instance in the document tree. W3C
1188 ID selectors represent an element instance based on its identifier. An
1191 identifier.</p>
1193 <p>Selectors does not specify how a UA knows the ID-typed attribute of
1194 an element. The UA may, e.g., read a document's DTD, have the
1195 information hard-coded or ask the user.
1202 <p>The following ID selector represents any element whose ID-typed
1205 <p>The following selector represents any element whose ID-typed
1208 </div>
1212 contains an element's IDs is contained in a DTD or a schema. When
1213 parsing XML, UAs do not always read the DTD, and thus may not know
1214 what the ID of an element is (though a UA may have namespace-specific
1215 knowledge that allows it to determine which attribute is the ID
1216 attribute for that namespace). If a style sheet designer knows or
1217 suspects that a UA may not know what the ID of an element is, he
1218 should use normal attribute selectors instead:
1222 <p>If an element has multiple ID attributes, all of them must be
1223 treated as IDs for that element for the purposes of the ID
1224 selector. Such a situation could be reached using mixtures of xml:id,
1225 DOM3 Core, XML DTDs, and namespace-specific knowledge.</p>
1229 <p>The pseudo-class concept is introduced to permit selection based on
1230 information that lies outside of the document tree or that cannot be
1231 expressed using the other simple selectors.</p>
1235 optionally by a value between parentheses.</p>
1237 <p>Pseudo-classes are allowed in all sequences of simple selectors
1238 contained in a selector. Pseudo-classes are allowed anywhere in
1239 sequences of simple selectors, after the leading type selector or
1240 universal selector (possibly omitted). Pseudo-class names are
1241 case-insensitive. Some pseudo-classes are mutually exclusive, while
1242 others can be applied simultaneously to the same
1243 element. Pseudo-classes may be dynamic, in the sense that an element
1244 may acquire or lose a pseudo-class while a user interacts with the
1245 document.</p>
1250 <p>Dynamic pseudo-classes classify elements on characteristics other
1251 than their name, attributes, or content, in principle characteristics
1252 that cannot be deduced from the document tree.</p>
1254 <p>Dynamic pseudo-classes do not appear in the document source or
1255 document tree.</p>
1260 <p>User agents commonly display unvisited links differently from
1261 previously visited ones. Selectors
1265 <ul>
1267 not yet been visited.</li>
1269 been visited by the user. </li>
1270 </ul>
1272 <p>After some amount of time, user agents may choose to return a
1273 visited link to the (unvisited) ':link' state.</p>
1281 <p>The following selector represents links carrying class
1286 </div>
1289 authors to abuse the :link and :visited pseudo-classes to determine
1290 which sites a user has visited without the user's consent.
1292 <p>UAs may therefore treat all links as unvisited links, or implement
1293 other measures to preserve the user's privacy while rendering visited
1294 and unvisited links differently.</p>
1297 :hover, :active, and :focus</a></h5>
1299 <p>Interactive user agents sometimes change the rendering in response
1300 to user actions. Selectors provides
1301 three pseudo-classes for the selection of an element the user is
1302 acting on.</p>
1304 <ul>
1307 designates an element with a pointing device, but does not activate
1308 it. For example, a visual user agent could apply this pseudo-class
1309 when the cursor (mouse pointer) hovers over a box generated by the
1310 element. User agents not that do not support <a
1312 media</a> do not have to support this pseudo-class. Some conforming
1313 user agents that support <a
1315 media</a> may not be able to support this pseudo-class (e.g., a pen
1316 device that does not detect hovering).</li>
1319 is being activated by the user. For example, between the times the
1320 user presses the mouse button and releases it.</li>
1323 has the focus (accepts keyboard or mouse events, or other forms of
1324 input). </li>
1326 </ul>
1328 <p>There may be document language or implementation specific limits on
1332 <p>These pseudo-classes are not mutually exclusive. An element may
1333 match several pseudo-classes at the same time.</p>
1335 <p>Selectors doesn't define if the parent of an element that is
1336 ':active' or ':hover' is also in that state.</p>
1340 <pre>a:link /* unvisited links */
1341 a:visited /* visited links */
1342 a:hover /* user hovers */
1343 a:active /* active links */</pre>
1345 <pre>a:focus
1346 a:focus:hover</pre>
1348 the pseudo-class :focus and in the pseudo-class :hover.</p>
1349 </div>
1352 and ':active' (or ':link' and ':active').</p>
1356 <p>Some URIs refer to a location within a resource. This kind of URI
1358 identifier (called the fragment identifier).</p>
1360 <p>URIs with fragment identifiers link to a certain element within the
1361 document, known as the target element. For instance, here is a URI
1363 document:</p>
1368 pseudo-class. If the document's URI has no fragment identifier, then
1369 the document has no target element.</p>
1376 URI.</p>
1377 </div>
1382 target element red and place an image before it, if there is one:</p>
1383 <pre>*:target { color : red }
1384 *:target::before { content : url(target.png) }</pre>
1385 </div>
1389 <p>If the document language specifies how the human language of an
1390 element is determined, it is possible to write selectors that
1391 represent an element based on its language. For example, in HTML <a
1394 element, and possibly by information from the protocol (such as HTTP
1396 there may be other document language-specific methods for determining
1397 the language.</p>
1400 is in language C. Whether an element is represented by a
1402 being either equal to, or a hyphen-separated substring of, the
1403 element's language value, in the same way as if performed by the <a
1405 selectors. The identifier C does not have to be a valid language
1406 name.</p>
1420 <p>The two following selectors represent an HTML document that is in
1421 Belgian, French, or German. The two next selectors represent
1423 or German.</p>
1424 <pre>html:lang(fr-be)
1425 html:lang(de)
1426 :lang(fr-be) > q
1428 </div>
1435 the look of user interface elements that are enabled — which the
1436 user can select or activate in some fashion (e.g. clicking on a button
1437 with a mouse). There is a need for such a pseudo-class because there
1438 is no way to programmatically specify the default appearance of say,
1440 would look like when it was disabled.</p>
1443 author to specify precisely how a disabled or inactive user interface
1444 element should look.</p>
1446 <p>Most elements will be neither enabled nor disabled. An element is
1447 enabled if the user can either activate it or transfer the focus to
1448 it. An element is disabled if it could be enabled, but the user cannot
1449 presently activate it or transfer focus to it.</p>
1454 <p>Radio and checkbox elements can be toggled by the user. Some menu
1455 items are "checked" when the user selects them. When such elements are
1459 attributes as described in <a
1464 in nature, and is altered by user action, since it can also be based
1473 <p>Radio and checkbox elements can be toggled by the user, but are
1474 sometimes in an indeterminate state, neither checked nor unchecked.
1475 This can be due to an element attribute, or DOM manipulation.</p>
1477 <p>A future version of this specification may introduce an
1479 <!--While the <code>:indeterminate</code> pseudo-class is dynamic in
1480 nature, and is altered by user action, since it can also be based on
1481 the presence of an element attribute, it applies to all media.</p>
1483 <p>Components of a radio-group initialized with no pre-selected choice
1486 </div>
1492 pseudo-classes</dfn> to permit selection based on extra information that lies in
1493 the document tree but cannot be represented by other simple selectors or
1494 combinators.
1496 <p>Note that standalone pieces of PCDATA (text nodes in the DOM) are
1497 not counted when calculating the position of an element in the list of
1498 children of its parent. When calculating the position of an element in
1499 the list of children of its parent, the index numbering starts at 1.
1505 the root of the document. In HTML 4, this is always the
1511 <p>The
1513 pseudo-class notation represents an element that has
1519 each. For example, this allows the selectors to address every other
1520 row in a table, and could be used to alternate the color
1523 integers. The index of the first child of an element is 1.
1534 tr:nth-child(odd) /* same */
1535 tr:nth-child(2n) /* represents every even row of an HTML table */
1536 tr:nth-child(even) /* same */
1538 /* Alternate paragraph colours in CSS */
1543 </div>
1548 included, so the syntax simplifies to
1556 </div>
1564 bar:nth-child(n+0) /* same */
1565 bar:nth-child(n) /* same */
1567 </div>
1576 </div>
1579 pseudo-class represents no element in the document tree.</p>
1584 tree.</p>
1589 </div>
1592 expression must be removed (it is effectively replaced by the "-"
1600 </div>
1606 pseudo-class notation represents an element that has
1612 as arguments.
1619 foo:nth-last-child(odd) /* represents all odd foo elements in their parent element,
1620 counting from the last one */</pre>
1621 </div>
1627 pseudo-class notation represents an element that has
1632 of that type after all the children of that type have been split into
1634 for the syntax of its argument. It also accepts the
1643 </div>
1649 pseudo-class notation represents an element that has
1661 following selector:</p>
1664 selector ends up being just as long:</p>
1666 </div>
1672 represents an element that is the first child of some other element.
1686 fragment:
1694 a:first-child /* Same (assuming a is not the root element) */</pre>
1695 </div>
1700 represents an element that is the last child of some other element.
1707 </div>
1712 represents an element that is the first sibling of its type in the list of
1713 children of its parent element.
1717 <p>The following selector represents a definition title
1720 its parent element.</p>
1723 elements in the following example but not for the third one:</p>
1735 </div>
1741 the last sibling of its type in the list of children of its parent
1742 element.</p>
1746 <p>The following selector represents the last data cell
1749 </div>
1753 <p>Represents an element that has a parent element and whose parent
1754 element has no other element children. Same as
1757 specificity.</p>
1761 <p>Represents an element that has a parent element and whose parent
1762 element has no other element children with the same element name. Same
1765 specificity.</p>
1771 no children at all. In terms of the DOM, only element nodes and text
1772 nodes (including CDATA nodes and entity references) whose data has a
1773 non-zero length must be considered as affecting emptiness; comments,
1774 PIs, and other nodes must not affect whether an element is considered
1775 empty or not.</p>
1782 following fragments:</p>
1786 </div>
1788 <h4><a name=content-selectors>6.6.6. Blank</a></h4> <!-- It's the Return of Appendix H!!! Run away! -->
1791 <!-- (used to be :contains()) -->
1797 selector</a> (excluding the negation pseudo-class itself and
1798 pseudo-elements) as an argument. It represents an element that is not
1799 represented by the argument.
1801 <!-- pseudo-elements are not simple selectors, so the above paragraph
1802 may be a bit confusing -->
1807 elements in an HTML document that are not disabled.</p>
1810 elements.</p>
1812 <p>The following group of selectors represents all HTML elements
1813 except links.</p>
1815 </div>
1817 <p>Default namespace declarations do not affect the argument of the
1818 negation pseudo-class unless the argument is a universal selector or a
1819 type selector.</p>
1823 <p>Assuming that the default namespace is bound to
1824 "http://example.com/", the following selector represents all
1825 elements that are not in that namespace:</p>
1827 <p>The following CSS selector matches any element being hovered,
1828 regardless of its namespace. In particular, it is not limited to
1829 only matching elements in the default namespace that are not being
1830 hovered, and elements not in the default namespace don't match the
1833 </div>
1839 specificity.</p>
1843 <p>Pseudo-elements create abstractions about the document tree beyond
1844 those specified by the document language. For instance, document
1845 languages do not offer mechanisms to access the first letter or first
1846 line of an element's content. Pseudo-elements allow designers to refer
1847 to this otherwise inaccessible information. Pseudo-elements may also
1848 provide designers a way to refer to content that does not exist in the
1851 content).</p>
1854 by the name of the pseudo-element.</p>
1857 in order to establish a discrimination between pseudo-classes and
1858 pseudo-elements. For compatibility with existing style sheets, user
1859 agents must also accept the previous one-colon notation for
1865 <p>Only one pseudo-element may appear per selector, and if present it
1866 must appear after the sequence of simple selectors that represents the
1868 future version of this specification may allow multiple
1869 pesudo-elements per selector.</span></p>
1874 of the first formatted line of an element.
1881 </div>
1884 HTML element. It does match a pseudo-element that conforming user
1885 agents will insert at the beginning of every paragraph.</p>
1887 <p>Note that the length of the first line depends on a number of
1888 factors, including the width of the page, the font size, etc. Thus,
1889 an ordinary HTML paragraph such as:</p>
1891 <pre>
1893 paragraph that will be broken into several
1894 lines. The first line will be identified
1895 by a fictional tag sequence. The other lines
1896 will be treated as ordinary lines in the
1898 </pre>
1900 <p>the lines of which happen to be broken as follows:
1902 <pre>
1903 THIS IS A SOMEWHAT LONG HTML PARAGRAPH THAT
1904 will be broken into several lines. The first
1905 line will be identified by a fictional tag
1906 sequence. The other lines will be treated as
1907 ordinary lines in the paragraph.
1908 </pre>
1912 fictional tag sequence helps to show how properties are inherited.</p>
1914 <pre>
1917 lines. The first line will be identified
1918 by a fictional tag sequence. The other lines
1919 will be treated as ordinary lines in the
1921 </pre>
1923 <p>If a pseudo-element breaks up a real element, the desired effect
1924 can often be described by a fictional tag sequence that closes and
1925 then re-opens the element. Thus, if we mark up the previous paragraph
1928 <pre>
1930 paragraph that will be broken into several
1932 by a fictional tag sequence. The other lines
1933 will be treated as ordinary lines in the
1935 </pre>
1937 <p>the user agent could simulate start and end tags for
1941 <pre>
1943 somewhat long HTML
1944 paragraph that will <b></SPAN></b></P::first-line><b><SPAN class="test"></b> be
1945 broken into several
1947 by a fictional tag sequence. The other lines
1948 will be treated as ordinary lines in the
1950 </pre>
1953 attached to a block-level element, an inline-block, a table-caption,
1954 or a table-cell.</p>
1957 element may occur inside a
1958 block-level descendant in the same flow (i.e., a block-level
1959 descendant that is not positioned and not a float). E.g., the first
1964 <p>The first line of a table-cell or inline-block cannot be the first
1975 <p>A UA should act as if the fictional start tags of the
1977 innermost enclosing block-level element. (Since CSS1 and CSS2 were
1978 silent on this case, authors should not rely on this behavior.) Here
1979 is an example. The fictional tag sequence for</p>
1981 <pre>
1986 </pre>
1990 <pre>
1992 <P><DIV::first-line><P::first-line>First paragraph</P::first-line></DIV::first-line></P>
1995 </pre>
1998 inline-level element, but with certain restrictions. In CSS, the
2000 pseudo-element: font properties, color property, background
2001 properties, 'word-spacing', 'letter-spacing', 'text-decoration',
2002 'vertical-align', 'text-transform', 'line-height'. UAs may apply other
2003 properties as well.</p>
2009 letter of the first line of a block, if it is not preceded by any
2010 other content (such as images or inline tables) on its line. The
2012 caps", which are common typographical effects. This type of initial
2013 letter is similar to an inline-level element if its 'float' property
2014 is 'none'; otherwise, it is similar to a floated element.</p>
2017 pseudo-elements: font properties, 'text-decoration', 'text-transform',
2018 'letter-spacing', 'word-spacing' (when appropriate), 'line-height',
2019 'float', 'vertical-align' (only if 'float' is 'none'), margin
2020 properties, padding properties, border properties, color property,
2021 background properties. UAs may apply other properties as well. To
2022 allow UAs to render a typographically correct drop cap or initial cap,
2023 the UA may choose a line-height, width and height based on the shape
2024 of the letter, unlike for normal elements.</p>
2028 <p>This example shows a possible rendering of an initial cap. Note
2030 pseudo-element is 1.1, but the UA in this example has computed the
2031 height of the first letter differently, so that it doesn't cause any
2032 unnecessary space between the first two lines. Also note that the
2035 <pre>
2036 p { line-height: 1.1 }
2037 p::first-letter { font-size: 3em; font-weight: normal }
2038 span { font-weight: bold }
2039 ...
2043 En dagelix geschrey de bange stad ontzet.
2044 </pre>
2047 </div>
2048 </div>
2053 <pre>
2060 P::first-letter { font-size: 200%; font-weight: bold; float: left }
2061 SPAN { text-transform: uppercase }
2069 </pre>
2074 <P><img src="first-letter.gif" alt="Image illustrating the combined effect of the ::first-letter and ::first-line pseudo-elements"></p>
2075 </div>
2080 <pre>
2084 T
2087 few words of an article in the Economist.
2089 </pre>
2092 the content (i.e., the initial character), while the ::first-line
2093 pseudo-element start tag is inserted right after the start tag of the
2094 block element.</p> </div>
2096 <p>In order to achieve traditional drop caps formatting, user agents
2097 may approximate font sizes, for example to align baselines. Also, the
2098 glyph outline may be taken into account when formatting.</p>
2102 punctuation classes), that precedes or follows the first letter should
2108 </div>
2115 block, list-item, table-cell, table-caption, and inline-block
2117 may allow this pesudo-element to apply to more element
2118 types.</span></p>
2121 such elements that contain text, or that have a descendant in the same
2122 flow that contains text. A UA should act as if the fictional start tag
2123 of the ::first-letter pseudo-element is just before the first text of
2124 the element, even if that first text is in a descendant.</p>
2128 <p>The fictional tag sequence for this HTMLfragment:
2131 <p>is:
2134 </div>
2136 <p>The first letter of a table-cell or inline-block cannot be the
2149 <p>In CSS, if an element is a list item ('display: list-item'), the
2151 principal box after the marker. UAs may ignore
2161 </div>
2163 <p>Some languages may have specific rules about how to treat certain
2164 letter combinations. In Dutch, for example, if the letter combination
2165 "ij" appears at the beginning of a word, both letters should be
2168 <p>If the letters that would form the ::first-letter are not in the
2170 may create a ::first-letter pseudo-element from one of the elements,
2171 both elements, or simply not create a pseudo-element.</p>
2173 <p>Similarly, if the first letter(s) of the block are not at the start
2174 of the line (for example due to bidirectional reordering), then the UA
2175 need not create the pseudo-element(s).
2180 how overlapping pseudo-elements may interact. The first letter of
2181 each P element will be green with a font size of '24pt'. The rest of
2182 the first formatted line will be 'blue' while the rest of the
2183 paragraph will be 'red'.</p>
2186 p::first-letter { color: green; font-size: 200% }
2187 p::first-line { color: blue }
2198 S
2201 ends up on two lines
2208 </div>
2214 of a document that has been highlighted by the user. This also
2215 applies, for example, to selected text within an editable text
2216 field. This pseudo-element should not be confused with the <code><a
2221 nature, and is altered by user action, it is reasonable to expect that
2222 when a UA re-renders to a static medium (such as a printed page, see
2224 dynamic medium (like screen), the UA may wish to transfer the current
2226 appropriate formatting and rendering take effect as well. This is not
2228 pseudo-element for static media.
2231 pseudo-elements: color, background, cursor (optional), outline
2232 (optional). The computed value of the 'background-image' property on
2239 can be used to describe generated content before or after an element's
2246 element including the inserted text.</p>
2252 <p>At times, authors may want selectors to describe an element that is
2253 the descendant of another element in the document tree (e.g., "an
2254 <code>EM</code> element that is contained within an <code>H1</code>
2255 element"). Descendant combinators express such a relationship. A
2257 separates two sequences of simple selectors. A selector of the form
2267 description of the following fragment:</p>
2274 either side of the "*" is not part of the universal selector; the
2275 whitespace is a combinator indicating that the DIV must be the
2276 ancestor of some element, and that that element must be an ancestor
2277 of the P.</p>
2278 <p>The following selector, which combines descendant combinators and
2283 </div>
2288 between two elements. A child combinator is made of the
2290 separates two sequences of simple selectors.
2298 <p>The following example combines descendant combinators and child
2299 combinators.</p>
2306 </div>
2308 <p>For information on selecting the first child of an element, please
2309 see the section on the <code><a
2311 above.</p>
2315 <p>There are two different sibling combinators: the adjacent sibling
2316 combinator and the general sibling combinator. In both cases,
2317 non-element nodes (e.g. text between elements) are ignored when
2318 considering adjacency of elements.</p>
2324 sequences of simple selectors. The elements represented by the two
2325 sequences share the same parent in the document tree and the element
2326 represented by the first sequence immediately precedes the element
2327 represented by the second one.</p>
2334 <p>The following selector is conceptually similar to the one in the
2335 previous example, except that it adds an attribute selector — it
2339 </div>
2346 simple selectors. The elements represented by the two sequences share
2347 the same parent in the document tree and the element represented by
2348 the first sequence precedes (not necessarily immediately) the element
2349 represented by the second one.</p>
2355 is a correct and valid, but partial, description of:</p>
2359 </div>
2365 <ul>
2367 <li>count the number of class selectors, attributes selectors, and pseudo-classes in the selector (= b)</li>
2370 </ul>
2373 are counted like any other, but the negation itself does not count as
2374 a pseudo-class.</p>
2376 <p>Concatenating the three numbers a-b-c (in a number system with a
2377 large base) gives the specificity.</p>
2390 </pre>
2391 </div>
2401 <p>The grammar below defines the syntax of Selectors. It is globally
2403 it directly, since it doesn't express the parsing conventions). The
2404 format of the productions is optimized for human consumption and some
2406 are used:</p>
2408 <ul>
2414 </ul>
2418 <pre>selectors_group
2419 : selector [ COMMA S* selector ]*
2420 ;
2422 selector
2423 : simple_selector_sequence [ combinator simple_selector_sequence ]*
2424 ;
2426 combinator
2427 /* combinators can be surrounded by white space */
2428 : PLUS S* | GREATER S* | TILDE S* | S+
2429 ;
2431 simple_selector_sequence
2432 : [ type_selector | universal ]
2433 [ HASH | class | attrib | pseudo | negation ]*
2434 | [ HASH | class | attrib | pseudo | negation ]+
2435 ;
2437 type_selector
2438 : [ namespace_prefix ]? element_name
2439 ;
2441 namespace_prefix
2442 : [ IDENT | '*' ]? '|'
2443 ;
2445 element_name
2446 : IDENT
2447 ;
2449 universal
2450 : [ namespace_prefix ]? '*'
2451 ;
2453 class
2454 : '.' IDENT
2455 ;
2457 attrib
2458 : '[' S* [ namespace_prefix ]? IDENT S*
2459 [ [ PREFIXMATCH |
2460 SUFFIXMATCH |
2461 SUBSTRINGMATCH |
2462 '=' |
2463 INCLUDES |
2464 DASHMATCH ] S* [ IDENT | STRING ] S*
2465 ]? ']'
2466 ;
2468 pseudo
2469 /* '::' starts a pseudo-element, ':' a pseudo-class */
2470 /* Exceptions: :first-line, :first-letter, :before and :after. */
2471 /* Note that pseudo-elements are restricted to one per selector and */
2472 /* occur only in the last simple_selector_sequence. */
2473 : ':' ':'? [ IDENT | functional_pseudo ]
2474 ;
2476 functional_pseudo
2477 : FUNCTION S* expression ')'
2478 ;
2480 expression
2481 /* In CSS3, the expressions are identifiers, strings, */
2482 /* or of the form "an+b" */
2483 : [ [ PLUS | '-' | DIMENSION | NUMBER | STRING | IDENT ] S* ]+
2484 ;
2486 negation
2487 : NOT S* negation_arg S* ')'
2488 ;
2490 negation_arg
2491 : type_selector | universal | HASH | class | attrib | pseudo
2492 ;</pre>
2499 case-insensitive.</p>
2502 number that current versions of Flex can deal with (decimal 255). They
2507 <pre>%option case-insensitive
2509 ident [-]?{nmstart}{nmchar}*
2510 name {nmchar}+
2511 nmstart [_a-z]|{nonascii}|{escape}
2514 escape {unicode}|\\[^\n\r\f0-9a-f]
2515 nmchar [_a-z0-9-]|{nonascii}|{escape}
2517 string {string1}|{string2}
2519 string2 \'([^\n\r\f\\']|\\{nl}|{nonascii}|{escape})*\'
2520 invalid {invalid1}|{invalid2}
2522 invalid2 \'([^\n\r\f\\']|\\{nl}|{nonascii}|{escape})*
2523 nl \n|\r\n|\r|\f
2524 w [ \t\r\n\f]*
2526 %%
2528 [ \t\r\n\f]+ return S;
2535 {ident} return IDENT;
2536 {string} return STRING;
2538 {num} return NUMBER;
2545 @{ident} return ATKEYWORD;
2546 {invalid} return INVALID;
2547 {num}% return PERCENTAGE;
2548 {num}{ident} return DIMENSION;
2554 U\+[0-9a-f?]{1,6}(-[0-9a-f]{1,6})? return UNICODE_RANGE;
2556 \/\*[^*]*\*+([^/*][^*]*\*+)*\/ /* ignore comments */
2558 . return *yytext;</pre>
2562 <h2><a name=downlevel>11. Namespaces and down-level clients</a></h2>
2564 <p>An important issue is the interaction of CSS selectors with XML
2565 documents in web clients that were produced prior to this
2566 document. Unfortunately, due to the fact that namespaces must be
2567 matched based on the URI which identifies the namespace, not the
2568 namespace prefix, some mechanism is required to identify namespaces in
2569 CSS by their URI as well. Without such a mechanism, it is impossible
2570 to construct a CSS style sheet which will properly match selectors in
2571 all cases against a random set of XML documents. However, given
2572 complete knowledge of the XML document to which a style sheet is to be
2573 applied, and a limited use of namespaces within the XML document, it
2574 is possible to construct a style sheet in which selectors would match
2575 elements and attributes correctly.</p>
2577 <p>It should be noted that a down-level CSS client will (if it
2578 properly conforms to CSS forward compatible parsing rules) ignore all
2579 <code>@namespace</code> at-rules, as well as all style rules that make
2580 use of namespace qualified element type or attribute selectors. The
2581 syntax of delimiting namespace prefixes in CSS was deliberately chosen
2582 so that down-level CSS clients would ignore the style rules rather
2583 than possibly match them incorrectly.</p>
2585 <p>The use of default namespaces in CSS makes it possible to write
2586 element type selectors that will function in both namespace aware CSS
2587 clients as well as down-level clients. It should be noted that
2588 down-level clients may incorrectly match selectors against XML
2589 elements in other namespaces.</p>
2591 <p>The following are scenarios and examples in which it is possible to
2592 construct style sheets which would function properly in web clients
2593 that do not implement this proposal.</p>
2595 <ol>
2596 <li>
2598 <p>The XML document does not use namespaces.</p>
2600 <ul>
2602 <li>In this case, it is obviously not necessary to declare or use
2603 namespaces in the style sheet. Standard CSS element type and
2604 attribute selectors will function adequately in a down-level
2605 client.</li>
2607 <li>In a CSS namespace aware client, the default behavior of
2608 element selectors matching without regard to namespace will
2609 function properly against all elements, since no namespaces are
2610 present. However, the use of specific element type selectors that
2612 will guarantee that selectors will match only XML elements that do
2613 not have a declared namespace. </li>
2615 </ul>
2617 </li>
2619 <li>
2621 <p>The XML document defines a single, default namespace used
2622 throughout the document. No namespace prefixes are used in element
2623 names.</p>
2625 <ul>
2627 <li>In this case, a down-level client will function as if
2628 namespaces were not used in the XML document at all. Standard CSS
2629 element type and attribute selectors will match against all
2630 elements. </li>
2632 </ul>
2634 </li>
2636 <li>
2638 <p>The XML document does <b>not</b> use a default namespace, all
2639 namespace prefixes used are known to the style sheet author, and
2640 there is a direct mapping between namespace prefixes and namespace
2641 URIs. (A given prefix may only be mapped to one namespace URI
2642 throughout the XML document; there may be multiple prefixes mapped
2643 to the same URI).</p>
2645 <ul>
2647 <li>In this case, the down-level client will view and match
2648 element type and attribute selectors based on their fully
2649 qualified name, not the local part as outlined in the <a
2652 to describe the fully qualified names, e.g.
2654 <code><html:h1></code>. Selectors using the qualified name
2655 will only match XML elements that use the same prefix. Other
2656 namespace prefixes used in the XML that are mapped to the same URI
2657 will not match as expected unless additional CSS style rules are
2658 declared for them.</li>
2660 <li>Note that selectors declared in this fashion will
2661 <em>only</em> match in down-level clients. A CSS namespace aware
2662 client will match element type and attribute selectors based on
2663 the name's local part. Selectors declared with the fully
2664 qualified name will not match (unless there is no namespace prefix
2665 in the fully qualified name).</li>
2667 </ul>
2669 </li>
2671 </ol>
2673 <p>In other scenarios: when the namespace prefixes used in the XML are
2674 not known in advance by the style sheet author; or a combination of
2675 elements with no namespace are used in conjunction with elements using
2676 a default namespace; or the same namespace prefix is mapped to
2677 <em>different</em> namespace URIs within the same document, or in
2678 different documents; it is impossible to construct a CSS style sheet
2679 that will function properly against all elements in those documents,
2680 unless, the style sheet is written using a namespace URI syntax (as
2681 outlined in this document or similar) and the document is processed by
2682 a CSS and XML namespace aware client.</p>
2684 <h2><a name=profiling>12. Profiles</a></h2>
2686 <p>Each specification using Selectors must define the subset of W3C
2687 Selectors it allows and excludes, and describe the local meaning of
2688 all the components of that subset.</p>
2690 <p>Non normative examples:
2694 <tbody>
2695 <tr>
2697 <tr>
2698 <th>Specification</th>
2699 <td>CSS level 1</td></tr>
2700 <tr>
2701 <th>Accepts</th>
2702 <td>type selectors<br>class selectors<br>ID selectors<br>:link,
2703 :visited and :active pseudo-classes<br>descendant combinator
2704 <br>::first-line and ::first-letter pseudo-elements</td></tr>
2705 <tr>
2706 <th>Excludes</th>
2707 <td>
2709 <p>universal selector<br>attribute selectors<br>:hover and :focus
2710 pseudo-classes<br>:target pseudo-class<br>:lang() pseudo-class<br>all UI
2711 element states pseudo-classes<br>all structural
2712 pseudo-classes<br>negation pseudo-class<br>all
2713 UI element fragments pseudo-elements<br>::before and ::after
2714 pseudo-elements<br>child combinators<br>sibling combinators
2716 <p>namespaces</td></tr>
2717 <tr>
2718 <th>Extra constraints</th>
2719 <td>only one class selector allowed per sequence of simple
2720 selectors</td></tr></tbody></table><br><br>
2722 <tbody>
2723 <tr>
2725 <tr>
2726 <th>Specification</th>
2727 <td>CSS level 2</td></tr>
2728 <tr>
2729 <th>Accepts</th>
2730 <td>type selectors<br>universal selector<br>attribute presence and
2731 values selectors<br>class selectors<br>ID selectors<br>:link, :visited,
2732 :active, :hover, :focus, :lang() and :first-child pseudo-classes
2733 <br>descendant combinator<br>child combinator<br>adjacent sibling
2734 combinator<br>::first-line and ::first-letter pseudo-elements<br>::before
2735 and ::after pseudo-elements</td></tr>
2736 <tr>
2737 <th>Excludes</th>
2738 <td>
2740 <p>content selectors<br>substring matching attribute
2741 selectors<br>:target pseudo-classes<br>all UI element
2742 states pseudo-classes<br>all structural pseudo-classes other
2743 than :first-child<br>negation pseudo-class<br>all UI element
2744 fragments pseudo-elements<br>general sibling combinators
2746 <p>namespaces</td></tr>
2747 <tr>
2748 <th>Extra constraints</th>
2749 <td>more than one class selector per sequence of simple selectors (CSS1
2750 constraint) allowed</td></tr></tbody></table>
2752 <p>In CSS, selectors express pattern matching rules that determine which style
2753 rules apply to elements in the document tree.
2755 <p>The following selector (CSS level 2) will <b>match</b> all anchors <code>a</code>
2756 with attribute <code>name</code> set inside a section 1 header <code>h1</code>:
2757 <pre>h1 a[name]</pre>
2759 <p>All CSS declarations attached to such a selector are applied to elements
2760 matching it. </div>
2764 <tbody>
2765 <tr>
2767 <tr>
2768 <th>Specification</th>
2769 <td>STTS 3</td>
2770 </tr>
2771 <tr>
2772 <th>Accepts</th>
2773 <td>
2775 <p>type selectors<br>universal selectors<br>attribute selectors<br>class
2776 selectors<br>ID selectors<br>all structural pseudo-classes<br>
2777 all combinators
2779 <p>namespaces</td></tr>
2780 <tr>
2781 <th>Excludes</th>
2782 <td>non-accepted pseudo-classes<br>pseudo-elements<br></td></tr>
2783 <tr>
2784 <th>Extra constraints</th>
2785 <td>some selectors and combinators are not allowed in fragment
2786 descriptions on the right side of STTS declarations.</td></tr></tbody></table>
2787 <form>
2813 </form>
2815 <p>Selectors can be used in STTS 3 in two different
2816 manners:
2817 <ol>
2818 <li>a selection mechanism equivalent to CSS selection mechanism: declarations
2819 attached to a given selector are applied to elements matching that selector,
2820 <li>fragment descriptions that appear on the right side of declarations.
2821 </li></ol></div>
2823 <h2><a name=Conformance></a>13. Conformance and requirements</h2>
2825 <p>This section defines conformance with the present specification only.
2827 <p>The inability of a user agent to implement part of this specification due to
2828 the limitations of a particular device (e.g., non interactive user agents will
2829 probably not implement dynamic pseudo-classes because they make no sense without
2830 interactivity) does not imply non-conformance.
2832 <p>All specifications reusing Selectors must contain a <a
2834 subset of Selectors it accepts or excludes, and describing the constraints
2835 it adds to the current specification.
2837 <p>Invalidity is caused by a parsing error, e.g. an unrecognized token or a token
2838 which is not allowed at the current parsing point.
2840 <p>User agents must observe the rules for handling parsing errors:
2841 <ul>
2842 <li>a simple selector containing an undeclared namespace prefix is invalid</li>
2843 <li>a selector containing an invalid simple selector, an invalid combinator
2844 or an invalid token is invalid. </li>
2845 <li>a group of selectors containing an invalid selector is invalid.</li>
2846 </ul>
2849 errors. (In the case of CSS, the entire rule in which the selector is
2850 used is dropped.)</p>
2852 <!-- Apparently all these references are out of date:
2853 <p>Implementations of this specification must behave as
2855 when parsing selectors and attempting matches. (In particular,
2856 implementations must assume the data is normalized and must not
2857 normalize it.) Normative rules for matching strings are defined in
2860 specification.</p>-->
2862 <h2><a name=Tests></a>14. Tests</h2>
2864 <p>This specification has <a
2866 suite</a> allowing user agents to verify their basic conformance to
2867 the specification. This test suite does not pretend to be exhaustive
2868 and does not cover all possible combined cases of Selectors.</p>
2870 <h2><a name=ACKS></a>15. Acknowledgements</h2>
2872 <p>The CSS working group would like to thank everyone who has sent
2873 comments on this specification over the years.</p>
2875 <p>The working group would like to extend special thanks to Donna
2876 McManus, Justin Baker, Joel Sklar, and Molly Ives Brower who perfermed
2877 the final editorial review.</p>
2879 <h2><a name=references>16. References</a></h2>
2883 <dt>[CSS1]
2884 <dd><a name=refsCSS1></a> Bert Bos, Håkon Wium Lie; "<cite>Cascading Style Sheets, level 1</cite>", W3C Recommendation, 17 Dec 1996, revised 11 Jan 1999
2887 <dt>[CSS21]
2888 <dd><a name=refsCSS21></a> Bert Bos, Tantek Çelik, Ian Hickson, Håkon Wium Lie, editors; "<cite>Cascading Style Sheets, level 2 revision 1</cite>", W3C Working Draft, 13 June 2005
2891 <dt>[CWWW]
2892 <dd><a name=refsCWWW></a> Martin J. Dürst, François Yergeau, Misha Wolf, Asmus Freytag, Tex Texin, editors; "<cite>Character Model for the World Wide Web</cite>", W3C Recommendation, 15 February 2005
2895 <dt>[FLEX]
2896 <dd><a name="refsFLEX"></a> "<cite>Flex: The Lexical Scanner Generator</cite>", Version 2.3.7, ISBN 1882114213
2898 <dt>[HTML4]
2899 <dd><a name="refsHTML4"></a> Dave Ragget, Arnaud Le Hors, Ian Jacobs, editors; "<cite>HTML 4.01 Specification</cite>", W3C Recommendation, 24 December 1999
2902 <dt>[MATH]
2903 <dd><a name="refsMATH"></a> Patrick Ion, Robert Miner, editors; "<cite>Mathematical Markup Language (MathML) 1.01</cite>", W3C Recommendation, revision of 7 July 1999
2904 <dd>(<code><a href="http://www.w3.org/TR/REC-MathML/">http://www.w3.org/TR/REC-MathML/</a></code>)
2906 <dt>[RFC3066]
2907 <dd><a name="refsRFC3066"></a> H. Alvestrand; "<cite>Tags for the Identification of Languages</cite>", Request for Comments 3066, January 2001
2908 <dd>(<a href="http://www.ietf.org/rfc/rfc3066.txt"><code>http://www.ietf.org/rfc/rfc3066.txt</code></a>)
2910 <dt>[STTS]
2911 <dd><a name=refsSTTS></a> Daniel Glazman; "<cite>Simple Tree Transformation Sheets 3</cite>", Electricité de France, submission to the W3C, 11 November 1998
2912 <dd>(<code><a href="http://www.w3.org/TR/NOTE-STTS3">http://www.w3.org/TR/NOTE-STTS3</a></code>)
2914 <dt>[SVG]
2915 <dd><a name="refsSVG"></a> Jon Ferraiolo, 藤沢 淳, Dean Jackson, editors; "<cite>Scalable Vector Graphics (SVG) 1.1 Specification</cite>", W3C Recommendation, 14 January 2003
2918 <dt>[UNICODE]</dt>
2920 href="http://www.unicode.org/versions/Unicode4.1.0/">The Unicode Standard, Version 4.1</a></cite>, The Unicode Consortium. Boston, MA, Addison-Wesley, March 2005. ISBN 0-321-18578-1, as amended by <a href="http://www.unicode.org/versions/Unicode4.0.1/">Unicode 4.0.1</a> and <a href="http://www.unicode.org/versions/Unicode4.1.0/">Unicode 4.1.0</a>.
2921 <dd>(<code><a href="http://www.unicode.org/versions/">http://www.unicode.org/versions/</a></code>)</dd>
2923 <dt>[XML10]
2924 <dd><a name="refsXML10"></a> Tim Bray, Jean Paoli, C. M. Sperberg-McQueen, Eve Maler, François Yergeau, editors; "<cite>Extensible Markup Language (XML) 1.0 (Third Edition)</cite>", W3C Recommendation, 4 February 2004
2927 <dt>[XMLNAMES]
2928 <dd><a name="refsXMLNAMES"></a> Tim Bray, Dave Hollander, Andrew Layman, editors; "<cite>Namespaces in XML</cite>", W3C Recommendation, 14 January 1999
2929 <dd>(<a href="http://www.w3.org/TR/REC-xml-names/"><code>http://www.w3.org/TR/REC-xml-names/</code></a>)
2931 <dt>[YACC]
2932 <dd><a name="refsYACC"></a> S. C. Johnson; "<cite>YACC — Yet another compiler compiler</cite>", Technical Report, Murray Hill, 1975
2934 </dl>
2935 </body>
2936 </html>