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108 <p><a href="http://www.w3.org/"><img height=48 alt=W3C src="http://www.w3.org/Icons/w3c_home" width=72></a>
114 <dl>
116 <dt>This version:
121 <dt>Latest version:
124 http://www.w3.org/TR/css3-selectors</a>
126 <dt>Previous version:
135 <dd class="vcard"><a lang="tr" class="url fn" href="http://www.tantek.com/">Tantek Çelik</a> (Invited Expert)
143 <dd class="vcard"><span class="fn">John Williams</span> (former editor, <span class="company"><a
146 </dl>
157 <a
159 <a
161 <a
163 use</a> rules apply.
167 </div>
172 tree. Selectors have been optimized for use with HTML and XML, and
173 are designed to be usable in performance-critical code.</p>
176 Style Sheets) is a language for describing the rendering of <acronym
179 screen, on paper, in speech, etc. CSS uses Selectors for binding
180 style properties to elements in the document. This document
181 describes extensions to the selectors defined in CSS level 2. These
182 extended selectors will be used by CSS level 3.
188 <p>That is, given an element and a selector, this specification
189 defines whether that element matches the selector.</p>
191 <p>These expressions can also be used, for instance, to select a set
192 of elements, or a single element from a set of elements, by
193 evaluating the expression across all the elements in a
200 <p><em>This section describes the status of this document at the
201 time of its publication. Other documents may supersede this
202 document. A list of current W3C publications and the latest revision
203 of this technical report can be found in the <a
205 http://www.w3.org/TR/.</a></em></p>
213 <p>The CSS Working Group doesn't expect that all implementations of
214 CSS3 will have to implement all selectors. Instead, there will
215 probably be a small number of variants of CSS3, called profiles. For
216 example, it may be that only a profile for interactive user agents
217 will include all of the selectors.</p>
222 document is a revision of the <a
225 implementation feedback received in the past few years. It is
226 expected that this last call will proceed straight to Proposed
227 Recommendation stage since it is believed that interoperability will
228 be demonstrable.</p>
230 <p>All persons are encouraged to review and implement this
231 specification and return comments to the (<a
233 public mailing list <a
236 Members can also send comments directly to the CSS Working
237 Group.
240 <p>This is still a draft document and may be updated, replaced, or
241 obsoleted by other documents at any time. It is inappropriate to
246 The English version of this specification is the only normative
247 version.
255 <ul>
259 </ul>
269 </ul>
271 <ul>
273 </ul>
276 <li class="tocline4"><a href="#attribute-representation">6.3.1. Representation of attributes and attributes values</a>
280 </ul>
290 <ul>
303 </ul>
305 </ul>
306 </li>
307 </ul>
309 <ul>
314 </ul>
321 <li class="tocline4"><a href="#adjacent-sibling-combinators">8.3.1. Adjacent sibling combinator</a>
322 <li class="tocline4"><a href="#general-sibling-combinators">8.3.2. General sibling combinator</a></li>
323 </ul>
324 </li>
325 </ul>
331 </ul>
338 </ul>
340 </div>
346 <p>Some features of this specification are specific to CSS, or have
347 particular limitations or rules specific to CSS. In this
348 specification, these have been described in terms of CSS2.1. <a
353 <p>All of the text of this specification is normative except
354 examples, notes, and sections explicitly marked as
355 non-normative.</p>
361 <p>The main differences between the selectors in CSS2 and those in
362 Selectors are:
364 <ul>
366 <li>the list of basic definitions (selector, group of selectors,
367 simple selector, etc.) has been changed; in particular, what was
368 referred to in CSS2 as a simple selector is now called a sequence
369 of simple selectors, and the term "simple selector" is now used for
370 the components of this sequence</li>
372 <li>an optional namespace component is now allowed in type element
373 selectors, the universal selector and attribute selectors</li>
377 <li>new simple selectors including substring matching attribute
378 selectors, and new pseudo-classes</li>
381 for pseudo-elements</li>
385 <li>profiles to be added to specifications integrating Selectors
386 and defining the set of selectors which is actually supported by
387 each specification</li>
389 <li>Selectors are now a CSS3 Module and an independent
390 specification; other specifications can now refer to this document
391 independently of CSS</li>
395 </ul>
399 <p><em>This section is non-normative, as it merely summarizes the
400 following sections.</em></p>
402 <p>A Selector represents a structure. This structure can be used as a
403 condition (e.g. in a CSS rule) that determines which elements a
404 selector matches in the document tree, or as a flat description of the
405 HTML or XML fragment corresponding to that structure.</p>
407 <p>Selectors may range from simple element names to rich contextual
408 representations.</p>
413 <thead>
414 <tr>
419 <tbody>
420 <tr>
425 selector</a></td>
427 <tr>
433 <tr>
438 selectors</a></td>
440 <tr>
446 selectors</a></td>
448 <tr>
454 selectors</a></td>
456 <tr>
462 selectors</a></td>
464 <tr>
470 selectors</a></td>
472 <tr>
478 selectors</a></td>
480 <tr>
486 selectors</a></td>
488 <tr>
493 pseudo-classes</a></td>
495 <tr>
500 pseudo-classes</a></td>
502 <tr>
505 from the last one</td>
508 pseudo-classes</a></td>
510 <tr>
515 pseudo-classes</a></td>
517 <tr>
520 from the last one</td>
523 pseudo-classes</a></td>
525 <tr>
530 pseudo-classes</a></td>
532 <tr>
537 pseudo-classes</a></td>
539 <tr>
544 pseudo-classes</a></td>
546 <tr>
551 pseudo-classes</a></td>
553 <tr>
558 pseudo-classes</a></td>
560 <tr>
565 pseudo-classes</a></td>
567 <tr>
570 nodes)</td>
573 pseudo-classes</a></td>
575 <tr>
578 which the target is not yet visited (:link) or already visited
579 (:visited)</td>
582 pseudo-classes</a></td>
584 <tr>
589 action pseudo-classes</a></td>
591 <tr>
596 pseudo-class</a></td>
598 <tr>
601 language specifies how language is determined)</td>
604 pseudo-class</a></td>
606 <tr>
609 disabled</td>
612 pseudo-classes</a></td>
614 <tr>
620 pseudo-classes</a></td>
622 <tr>
627 pseudo-element</a></td>
629 <tr>
634 pseudo-element</a></td>
636 <tr>
639 selected/highlighted by the user</td>
642 fragments pseudo-elements</a></td>
644 <tr>
649 pseudo-element</a></td>
651 <tr>
656 pseudo-element</a></td>
658 <tr>
664 selectors</a></td>
666 <tr>
671 selectors</a></td>
673 <tr>
678 pseudo-class</a></td>
680 <tr>
685 combinator</a></td>
687 <tr>
692 combinator</a></td>
694 <tr>
700 <tr>
707 <p>The meaning of each selector is derived from the table above by
709 column.</p>
713 <p>The case sensitivity of document language element names, attribute
714 names, and attribute values in selectors depends on the document
715 language. For example, in HTML, element names are case-insensitive,
716 but in XML, they are case-sensitive.</p>
729 selector or universal selector is allowed in the sequence.</p>
741 sequence of simple selectors.</p>
746 space may appear between a combinator and the simple selectors around
751 never part of white space.</p>
753 <p>The elements of a document tree that are represented by a selector
755 selector consisting of a single sequence of simple selectors
756 represents any element satisfying its requirements. Prepending another
757 sequence of simple selectors and a combinator to a sequence imposes
758 additional matching constraints, so the subjects of a selector are
759 always a subset of the elements represented by the last sequence of
760 simple selectors.</p>
762 <p>An empty selector, containing no sequence of simple selectors and
768 <p>When several selectors share the same declarations, they may be
773 <p>In this example, we condense three rules with identical
774 declarations into one. Thus,</p>
775 <pre>h1 { font-family: sans-serif }
776 h2 { font-family: sans-serif }
777 h3 { font-family: sans-serif }</pre>
780 </div>
783 because all the selectors are valid selectors. If just one of these
784 selectors were invalid, the entire group of selectors would be
785 invalid. This would invalidate the rule for all three heading
786 elements, whereas in the former case only one of the three individual
787 heading rules would be invalidated.</p>
795 element type. A type selector represents an instance of the element
796 type in the document tree.</p>
802 </div>
809 that has been previously declared may be prepended to the element name
813 <p>The namespace component may be left empty to indicate that the
814 selector is only to represent elements with no declared namespace.</p>
816 <p>An asterisk may be used for the namespace prefix, indicating that
817 the selector represents elements in any namespace (including elements
818 with no namespace).</p>
820 <p>Element type selectors that have no namespace component (no
821 namespace separator), represent elements without regard to the
822 element's namespace (equivalent to "<code>*|</code>") unless a default
823 namespace has been declared. If a default namespace has been declared,
824 the selector will represent only elements in the default
825 namespace.</p>
827 <p>A type selector containing a namespace prefix that has not been
829 The mechanism for declaring a namespace prefix is left up to the
830 language implementing Selectors. In CSS, such a mechanism is defined
831 in the General Syntax module.</p>
833 <p>In a namespace-aware client, element type selectors will only match
834 against the <a
836 of the element's <a
839 behaviors in down-level clients.</p>
843 <dl>
847 <dd>elements with name E in any namespace, including those without any
848 declared namespace</dd>
852 <dd>if no default namespace has been specified, this is equivalent to *|E.
853 Otherwise it is equivalent to ns|E where ns is the default namespace.</dd>
854 </dl>
859 <pre>@namespace foo url(http://www.example.com);
860 foo|h1 { color: blue }
861 foo|* { color: yellow }
862 |h1 { color: red }
863 *|h1 { color: green }
864 h1 { color: green }</pre>
869 <p>The second rule will match all elements in the
873 any declared namespace.</p>
876 namespace (including those without any declared namespace).</p>
878 <p>The last rule is equivalent to the fourth rule because no default
879 namespace has been defined.</p>
881 </div>
887 type. It represents any single element in the document tree in any
888 namespace (including those without any declared namespace) if no
889 default namespace has been specified. If a default namespace has been
893 <p>If the universal selector is not the only component of a sequence
898 <ul>
902 </ul>
903 </div>
907 omitted.</p>
911 <p>The universal selector allows an optional namespace component. It
912 is used as follows:</p>
914 <dl>
922 <dd>if no default namespace has been specified, this is equivalent to *|*.
923 Otherwise it is equivalent to ns|* where ns is the default namespace.</dd>
924 </dl>
926 <p>A universal selector containing a namespace prefix that has not
928 selector. The mechanism for declaring a namespace prefix is left up
929 to the language implementing Selectors. In CSS, such a mechanism is
930 defined in the General Syntax module.</p>
935 <p>Selectors allow the representation of an element's attributes. When
936 a selector is used as an expression to match against an element,
937 attribute selectors must be considered to match an element if that
938 element has an attribute that matches the attribute represented by the
939 attribute selector.</p>
942 selectors</a></h4>
946 <dl>
949 the attribute.</dd>
958 spaces).</dd>
968 </dl>
970 <p>Attribute values must be identifiers or strings. The
971 case-sensitivity of attribute names and values in selectors depends on
972 the document language.</p>
980 value:</p>
984 <p>In the following example, the selector represents a
990 <p>Multiple attribute selectors can be used to represent several
991 attributes of an element, or several conditions on the same
1000 and "~=". The first selector will represent, for example, the value
1020 <p>Similarly, the following selectors represents a
1024 <pre>DIALOGUE[character=romeo]
1025 DIALOGUE[character=juliet]</pre>
1027 </div>
1030 selectors</h4>
1032 <p>Three additional attribute selectors are provided for matching
1033 substrings in the value of an attribute:</p>
1035 <dl>
1045 </dl>
1047 <p>Attribute values must be identifiers or strings. The
1048 case-sensitivity of attribute names in selectors depends on the
1049 document language.</p>
1054 image:</p>
1062 </div>
1066 <p>Attribute selectors allow an optional namespace component to the
1067 attribute name. A namespace prefix that has been previously declared
1068 may be prepended to the attribute name separated by the namespace
1070 the Namespaces in the XML recommendation, default namespaces do not
1071 apply to attributes, therefore attribute selectors without a namespace
1072 component apply only to attributes that have no declared namespace
1073 (equivalent to "<code>|attr</code>"). An asterisk may be used for the
1074 namespace prefix indicating that the selector is to match all
1075 attribute names without regard to the attribute's namespace.
1077 <p>An attribute selector with an attribute name containing a namespace
1078 prefix that has not been previously declared is an <a
1080 a namespace prefix is left up to the language implementing Selectors.
1081 In CSS, such a mechanism is defined in the General Syntax module.
1086 [foo|att=val] { color: blue }
1087 [*|att] { color: yellow }
1088 [|att] { color: green }
1089 [att] { color: green }</pre>
1091 <p>The first rule will match only elements with the attribute
1095 <p>The second rule will match only elements with the attribute
1097 (including no declared namespace).</p>
1099 <p>The last two rules are equivalent and will match only elements
1101 declared to be in a namespace.</p>
1103 </div>
1107 <p>Attribute selectors represent explicitly set attribute values in
1108 the document tree. Default attribute values may be defined in a DTD or
1109 elsewhere, but cannot always be selected by attribute
1110 selectors. Selectors should be designed so that they work even if the
1111 default values are not included in the document tree.</p>
1120 knowledge of that namespace to treat default attribute values as if
1121 they were present in the document. (For example, an XHTML UA is not
1122 required to use its built-in knowledge of the XHTML DTD.)</p>
1125 choose to ignore external subsets.</p>
1137 <pre>EXAMPLE[notation=decimal] { /*... default property settings ...*/ }
1138 EXAMPLE[notation=octal] { /*... other settings...*/ }</pre>
1141 is set by default, i.e. not set explicitly. To catch all cases, the
1142 attribute selector for the default value must be dropped:</p>
1144 <pre>EXAMPLE { /*... default property settings ...*/ }
1145 EXAMPLE[notation=octal] { /*... other settings...*/ }</pre>
1148 more specific than the tag
1149 selector alone, the style declarations in the second rule will override
1150 those in the first for elements that have a "notation" attribute value
1151 of "octal". Care has to be taken that all property declarations that
1152 are to apply only to the default case are overridden in the non-default
1153 cases' style rules.</p>
1155 </div>
1163 the same meaning. The attribute value must immediately follow the
1166 <p>UAs may apply selectors using the period (.) notation in XML
1167 documents if the UA has namespace-specific knowledge that allows it to
1169 respective namespace. One such example of namespace-specific knowledge
1170 is the prose in the specification for a particular namespace (e.g. SVG
1181 <p>We can assign style information to all elements with
1190 <p>The following assigns style only to H1 elements with
1195 <p>Given these rules, the first H1 instance below would not have
1196 green text, while the second would:</p>
1201 </div>
1211 has been assigned a list of <a
1221 </div>
1224 power to the "class" attribute, authors could conceivably design their
1225 own "document language" based on elements with almost no associated
1226 presentation (such as DIV and SPAN in HTML) and assigning style
1227 information through the "class" attribute. Authors should avoid this
1228 practice since the structural elements of a document language often
1229 have recognized and accepted meanings and author-defined classes may
1230 not.</p>
1233 class attributes, their values must be concatenated with spaces
1234 between the values before searching for the class. As of this time the
1235 working group is not aware of any manner in which this situation can
1236 be reached, however, so this behavior is explicitly non-normative in
1237 this specification.</p>
1241 <p>Document languages may contain attributes that are declared to be
1242 of type ID. What makes attributes of type ID special is that no two
1243 such attributes can have the same value in a document, regardless of
1244 the type of the elements that carry them; whatever the document
1245 language, an ID typed attribute can be used to uniquely identify its
1246 element. In HTML all ID attributes are named "id"; XML applications
1247 may name ID attributes differently, but the same restriction
1248 applies.</p>
1250 <p>An ID-typed attribute of a document language allows authors to
1251 assign an identifier to one element instance in the document tree. W3C
1252 ID selectors represent an element instance based on its identifier. An
1255 identifier.</p>
1257 <p>Selectors does not specify how a UA knows the ID-typed attribute of
1258 an element. The UA may, e.g., read a document's DTD, have the
1259 information hard-coded or ask the user.
1266 <p>The following ID selector represents any element whose ID-typed
1269 <p>The following selector represents any element whose ID-typed
1272 </div>
1276 contains an element's IDs is contained in a DTD or a schema. When
1277 parsing XML, UAs do not always read the DTD, and thus may not know
1278 what the ID of an element is (though a UA may have namespace-specific
1279 knowledge that allows it to determine which attribute is the ID
1280 attribute for that namespace). If a style sheet designer knows or
1281 suspects that a UA may not know what the ID of an element is, he
1282 should use normal attribute selectors instead:
1286 <p>If an element has multiple ID attributes, all of them must be
1287 treated as IDs for that element for the purposes of the ID
1288 selector. Such a situation could be reached using mixtures of xml:id,
1289 DOM3 Core, XML DTDs, and namespace-specific knowledge.</p>
1293 <p>The pseudo-class concept is introduced to permit selection based on
1294 information that lies outside of the document tree or that cannot be
1295 expressed using the other simple selectors.</p>
1299 optionally by a value between parentheses.</p>
1301 <p>Pseudo-classes are allowed in all sequences of simple selectors
1302 contained in a selector. Pseudo-classes are allowed anywhere in
1303 sequences of simple selectors, after the leading type selector or
1304 universal selector (possibly omitted). Pseudo-class names are
1305 case-insensitive. Some pseudo-classes are mutually exclusive, while
1306 others can be applied simultaneously to the same
1307 element. Pseudo-classes may be dynamic, in the sense that an element
1308 may acquire or lose a pseudo-class while a user interacts with the
1309 document.</p>
1314 <p>Dynamic pseudo-classes classify elements on characteristics other
1315 than their name, attributes, or content, in principle characteristics
1316 that cannot be deduced from the document tree.</p>
1318 <p>Dynamic pseudo-classes do not appear in the document source or
1319 document tree.</p>
1324 <p>User agents commonly display unvisited links differently from
1325 previously visited ones. Selectors
1329 <ul>
1331 not yet been visited.</li>
1333 been visited by the user. </li>
1334 </ul>
1336 <p>After some amount of time, user agents may choose to return a
1337 visited link to the (unvisited) ':link' state.</p>
1345 <p>The following selector represents links carrying class
1350 </div>
1353 authors to abuse the :link and :visited pseudo-classes to determine
1354 which sites a user has visited without the user's consent.
1356 <p>UAs may therefore treat all links as unvisited links, or implement
1357 other measures to preserve the user's privacy while rendering visited
1358 and unvisited links differently.</p>
1361 :hover, :active, and :focus</a></h5>
1363 <p>Interactive user agents sometimes change the rendering in response
1364 to user actions. Selectors provides
1365 three pseudo-classes for the selection of an element the user is
1366 acting on.</p>
1368 <ul>
1371 designates an element with a pointing device, but does not activate
1372 it. For example, a visual user agent could apply this pseudo-class
1373 when the cursor (mouse pointer) hovers over a box generated by the
1374 element. User agents not that do not support <a
1376 media</a> do not have to support this pseudo-class. Some conforming
1377 user agents that support <a
1379 media</a> may not be able to support this pseudo-class (e.g., a pen
1380 device that does not detect hovering).</li>
1383 is being activated by the user. For example, between the times the
1384 user presses the mouse button and releases it.</li>
1387 has the focus (accepts keyboard or mouse events, or other forms of
1388 input). </li>
1390 </ul>
1392 <p>There may be document language or implementation specific limits on
1396 <p>These pseudo-classes are not mutually exclusive. An element may
1397 match several pseudo-classes at the same time.</p>
1399 <p>Selectors doesn't define if the parent of an element that is
1400 ':active' or ':hover' is also in that state.</p>
1404 <pre>a:link /* unvisited links */
1405 a:visited /* visited links */
1406 a:hover /* user hovers */
1407 a:active /* active links */</pre>
1409 <pre>a:focus
1410 a:focus:hover</pre>
1412 the pseudo-class :focus and in the pseudo-class :hover.</p>
1413 </div>
1416 and ':active' (or ':link' and ':active').</p>
1420 <p>Some URIs refer to a location within a resource. This kind of URI
1422 identifier (called the fragment identifier).</p>
1424 <p>URIs with fragment identifiers link to a certain element within the
1425 document, known as the target element. For instance, here is a URI
1427 document:</p>
1432 pseudo-class. If the document's URI has no fragment identifier, then
1433 the document has no target element.</p>
1440 URI.</p>
1441 </div>
1446 target element red and place an image before it, if there is one:</p>
1447 <pre>*:target { color : red }
1448 *:target::before { content : url(target.png) }</pre>
1449 </div>
1453 <p>If the document language specifies how the human language of an
1454 element is determined, it is possible to write selectors that
1455 represent an element based on its language. For example, in HTML <a
1458 element, and possibly by information from the protocol (such as HTTP
1460 there may be other document language-specific methods for determining
1461 the language.</p>
1464 is in language C. Whether an element is represented by a
1466 being either equal to, or a hyphen-separated substring of, the
1467 element's language value, in the same way as if performed by the <a
1469 selectors. The identifier C does not have to be a valid language
1470 name.</p>
1484 <p>The two following selectors represent an HTML document that is in
1485 Belgian, French, or German. The two next selectors represent
1487 or German.</p>
1488 <pre>html:lang(fr-be)
1489 html:lang(de)
1490 :lang(fr-be) > q
1492 </div>
1499 the look of user interface elements that are enabled — which the
1500 user can select or activate in some fashion (e.g. clicking on a button
1501 with a mouse). There is a need for such a pseudo-class because there
1502 is no way to programmatically specify the default appearance of say,
1504 would look like when it was disabled.</p>
1507 author to specify precisely how a disabled or inactive user interface
1508 element should look.</p>
1510 <p>Most elements will be neither enabled nor disabled. An element is
1511 enabled if the user can either activate it or transfer the focus to
1512 it. An element is disabled if it could be enabled, but the user cannot
1513 presently activate it or transfer focus to it.</p>
1518 <p>Radio and checkbox elements can be toggled by the user. Some menu
1519 items are "checked" when the user selects them. When such elements are
1523 attributes as described in <a
1528 in nature, and is altered by user action, since it can also be based
1537 <p>Radio and checkbox elements can be toggled by the user, but are
1538 sometimes in an indeterminate state, neither checked nor unchecked.
1539 This can be due to an element attribute, or DOM manipulation.</p>
1541 <p>A future version of this specification may introduce an
1543 <!--While the <code>:indeterminate</code> pseudo-class is dynamic in
1544 nature, and is altered by user action, since it can also be based on
1545 the presence of an element attribute, it applies to all media.</p>
1547 <p>Components of a radio-group initialized with no pre-selected choice
1550 </div>
1556 pseudo-classes</dfn> to permit selection based on extra information that lies in
1557 the document tree but cannot be represented by other simple selectors or
1558 combinators.
1560 <p>Note that standalone pieces of PCDATA (text nodes in the DOM) are
1561 not counted when calculating the position of an element in the list of
1562 children of its parent. When calculating the position of an element in
1563 the list of children of its parent, the index numbering starts at 1.
1569 the root of the document. In HTML 4, this is always the
1575 <p>The
1577 pseudo-class notation represents an element that has
1583 each. For example, this allows the selectors to address every other
1584 row in a table, and could be used to alternate the color
1587 integers. The index of the first child of an element is 1.
1598 tr:nth-child(odd) /* same */
1599 tr:nth-child(2n) /* represents every even row of an HTML table */
1600 tr:nth-child(even) /* same */
1602 /* Alternate paragraph colours in CSS */
1607 </div>
1612 included, so the syntax simplifies to
1620 </div>
1628 bar:nth-child(n+0) /* same */
1629 bar:nth-child(n) /* same */
1631 </div>
1640 </div>
1643 pseudo-class represents no element in the document tree.</p>
1648 tree.</p>
1653 </div>
1656 expression must be removed (it is effectively replaced by the "-"
1664 </div>
1670 pseudo-class notation represents an element that has
1676 as arguments.
1683 foo:nth-last-child(odd) /* represents all odd foo elements in their parent element,
1684 counting from the last one */</pre>
1685 </div>
1691 pseudo-class notation represents an element that has
1696 of that type after all the children of that type have been split into
1698 for the syntax of its argument. It also accepts the
1707 </div>
1713 pseudo-class notation represents an element that has
1725 following selector:</p>
1728 selector ends up being just as long:</p>
1730 </div>
1736 represents an element that is the first child of some other element.
1750 fragment:
1758 a:first-child /* Same (assuming a is not the root element) */</pre>
1759 </div>
1764 represents an element that is the last child of some other element.
1771 </div>
1776 represents an element that is the first sibling of its type in the list of
1777 children of its parent element.
1781 <p>The following selector represents a definition title
1784 its parent element.</p>
1787 elements in the following example but not for the third one:</p>
1799 </div>
1805 the last sibling of its type in the list of children of its parent
1806 element.</p>
1810 <p>The following selector represents the last data cell
1813 </div>
1817 <p>Represents an element that has a parent element and whose parent
1818 element has no other element children. Same as
1821 specificity.</p>
1825 <p>Represents an element that has a parent element and whose parent
1826 element has no other element children with the same element name. Same
1829 specificity.</p>
1835 no children at all. In terms of the DOM, only element nodes and text
1836 nodes (including CDATA nodes and entity references) whose data has a
1837 non-zero length must be considered as affecting emptiness; comments,
1838 PIs, and other nodes must not affect whether an element is considered
1839 empty or not.</p>
1846 following fragments:</p>
1850 </div>
1852 <h4><a name=content-selectors>6.6.6. Blank</a></h4> <!-- It's the Return of Appendix H!!! Run away! -->
1855 <!-- (used to be :contains()) -->
1861 selector</a> (excluding the negation pseudo-class itself and
1862 pseudo-elements) as an argument. It represents an element that is not
1863 represented by the argument.
1865 <!-- pseudo-elements are not simple selectors, so the above paragraph
1866 may be a bit confusing -->
1871 elements in an HTML document that are not disabled.</p>
1874 elements.</p>
1876 <p>The following group of selectors represents all HTML elements
1877 except links.</p>
1879 </div>
1881 <p>Default namespace declarations do not affect the argument of the
1882 negation pseudo-class unless the argument is a universal selector or a
1883 type selector.</p>
1887 <p>Assuming that the default namespace is bound to
1888 "http://example.com/", the following selector represents all
1889 elements that are not in that namespace:</p>
1891 <p>The following CSS selector matches any element being hovered,
1892 regardless of its namespace. In particular, it is not limited to
1893 only matching elements in the default namespace that are not being
1894 hovered, and elements not in the default namespace don't match the
1897 </div>
1903 specificity.</p>
1907 <p>Pseudo-elements create abstractions about the document tree beyond
1908 those specified by the document language. For instance, document
1909 languages do not offer mechanisms to access the first letter or first
1910 line of an element's content. Pseudo-elements allow designers to refer
1911 to this otherwise inaccessible information. Pseudo-elements may also
1912 provide designers a way to refer to content that does not exist in the
1915 content).</p>
1918 by the name of the pseudo-element.</p>
1921 in order to establish a discrimination between pseudo-classes and
1922 pseudo-elements. For compatibility with existing style sheets, user
1923 agents must also accept the previous one-colon notation for
1929 <p>Only one pseudo-element may appear per selector, and if present it
1930 must appear after the sequence of simple selectors that represents the
1932 future version of this specification may allow multiple
1933 pesudo-elements per selector.</span></p>
1938 of the first formatted line of an element.
1945 </div>
1948 HTML element. It does match a pseudo-element that conforming user
1949 agents will insert at the beginning of every paragraph.</p>
1951 <p>Note that the length of the first line depends on a number of
1952 factors, including the width of the page, the font size, etc. Thus,
1953 an ordinary HTML paragraph such as:</p>
1955 <pre>
1957 paragraph that will be broken into several
1958 lines. The first line will be identified
1959 by a fictional tag sequence. The other lines
1960 will be treated as ordinary lines in the
1962 </pre>
1964 <p>the lines of which happen to be broken as follows:
1966 <pre>
1967 THIS IS A SOMEWHAT LONG HTML PARAGRAPH THAT
1968 will be broken into several lines. The first
1969 line will be identified by a fictional tag
1970 sequence. The other lines will be treated as
1971 ordinary lines in the paragraph.
1972 </pre>
1976 fictional tag sequence helps to show how properties are inherited.</p>
1978 <pre>
1981 lines. The first line will be identified
1982 by a fictional tag sequence. The other lines
1983 will be treated as ordinary lines in the
1985 </pre>
1987 <p>If a pseudo-element breaks up a real element, the desired effect
1988 can often be described by a fictional tag sequence that closes and
1989 then re-opens the element. Thus, if we mark up the previous paragraph
1992 <pre>
1994 paragraph that will be broken into several
1996 by a fictional tag sequence. The other lines
1997 will be treated as ordinary lines in the
1999 </pre>
2001 <p>the user agent could simulate start and end tags for
2005 <pre>
2007 somewhat long HTML
2008 paragraph that will <b></SPAN></b></P::first-line><b><SPAN class="test"></b> be
2009 broken into several
2011 by a fictional tag sequence. The other lines
2012 will be treated as ordinary lines in the
2014 </pre>
2017 attached to a block-level element, an inline-block, a table-caption,
2018 or a table-cell.</p>
2021 element may occur inside a
2022 block-level descendant in the same flow (i.e., a block-level
2023 descendant that is not positioned and not a float). E.g., the first
2028 <p>The first line of a table-cell or inline-block cannot be the first
2039 <p>A UA should act as if the fictional start tags of the
2041 innermost enclosing block-level element. (Since CSS1 and CSS2 were
2042 silent on this case, authors should not rely on this behavior.) Here
2043 is an example. The fictional tag sequence for</p>
2045 <pre>
2050 </pre>
2054 <pre>
2056 <P><DIV::first-line><P::first-line>First paragraph</P::first-line></DIV::first-line></P>
2059 </pre>
2062 inline-level element, but with certain restrictions. In CSS, the
2064 pseudo-element: font properties, color property, background
2065 properties, 'word-spacing', 'letter-spacing', 'text-decoration',
2066 'vertical-align', 'text-transform', 'line-height'. UAs may apply other
2067 properties as well.</p>
2073 letter of the first line of a block, if it is not preceded by any
2074 other content (such as images or inline tables) on its line. The
2076 caps", which are common typographical effects. This type of initial
2077 letter is similar to an inline-level element if its 'float' property
2078 is 'none'; otherwise, it is similar to a floated element.</p>
2081 pseudo-elements: font properties, 'text-decoration', 'text-transform',
2082 'letter-spacing', 'word-spacing' (when appropriate), 'line-height',
2083 'float', 'vertical-align' (only if 'float' is 'none'), margin
2084 properties, padding properties, border properties, color property,
2085 background properties. UAs may apply other properties as well. To
2086 allow UAs to render a typographically correct drop cap or initial cap,
2087 the UA may choose a line-height, width and height based on the shape
2088 of the letter, unlike for normal elements.</p>
2092 <p>This example shows a possible rendering of an initial cap. Note
2094 pseudo-element is 1.1, but the UA in this example has computed the
2095 height of the first letter differently, so that it doesn't cause any
2096 unnecessary space between the first two lines. Also note that the
2099 <pre>
2100 p { line-height: 1.1 }
2101 p::first-letter { font-size: 3em; font-weight: normal }
2102 span { font-weight: bold }
2103 ...
2107 En dagelix geschrey de bange stad ontzet.
2108 </pre>
2111 </div>
2112 </div>
2117 <pre>
2124 P::first-letter { font-size: 200%; font-weight: bold; float: left }
2125 SPAN { text-transform: uppercase }
2133 </pre>
2138 <P><img src="first-letter.gif" alt="Image illustrating the combined effect of the ::first-letter and ::first-line pseudo-elements"></p>
2139 </div>
2144 <pre>
2148 T
2151 few words of an article in the Economist.
2153 </pre>
2156 the content (i.e., the initial character), while the ::first-line
2157 pseudo-element start tag is inserted right after the start tag of the
2158 block element.</p> </div>
2160 <p>In order to achieve traditional drop caps formatting, user agents
2161 may approximate font sizes, for example to align baselines. Also, the
2162 glyph outline may be taken into account when formatting.</p>
2166 punctuation classes), that precedes or follows the first letter should
2172 </div>
2179 block, list-item, table-cell, table-caption, and inline-block
2181 may allow this pesudo-element to apply to more element
2182 types.</span></p>
2185 such elements that contain text, or that have a descendant in the same
2186 flow that contains text. A UA should act as if the fictional start tag
2187 of the ::first-letter pseudo-element is just before the first text of
2188 the element, even if that first text is in a descendant.</p>
2192 <p>The fictional tag sequence for this HTMLfragment:
2195 <p>is:
2198 </div>
2200 <p>The first letter of a table-cell or inline-block cannot be the
2213 <p>In CSS, if an element is a list item ('display: list-item'), the
2215 principal box after the marker. UAs may ignore
2225 </div>
2227 <p>Some languages may have specific rules about how to treat certain
2228 letter combinations. In Dutch, for example, if the letter combination
2229 "ij" appears at the beginning of a word, both letters should be
2232 <p>If the letters that would form the ::first-letter are not in the
2234 may create a ::first-letter pseudo-element from one of the elements,
2235 both elements, or simply not create a pseudo-element.</p>
2237 <p>Similarly, if the first letter(s) of the block are not at the start
2238 of the line (for example due to bidirectional reordering), then the UA
2239 need not create the pseudo-element(s).
2244 how overlapping pseudo-elements may interact. The first letter of
2245 each P element will be green with a font size of '24pt'. The rest of
2246 the first formatted line will be 'blue' while the rest of the
2247 paragraph will be 'red'.</p>
2250 p::first-letter { color: green; font-size: 200% }
2251 p::first-line { color: blue }
2262 S
2265 ends up on two lines
2272 </div>
2278 of a document that has been highlighted by the user. This also
2279 applies, for example, to selected text within an editable text
2280 field. This pseudo-element should not be confused with the <code><a
2285 nature, and is altered by user action, it is reasonable to expect that
2286 when a UA re-renders to a static medium (such as a printed page, see
2288 dynamic medium (like screen), the UA may wish to transfer the current
2290 appropriate formatting and rendering take effect as well. This is not
2292 pseudo-element for static media.
2295 pseudo-elements: color, background, cursor (optional), outline
2296 (optional). The computed value of the 'background-image' property on
2303 can be used to describe generated content before or after an element's
2310 element including the inserted text.</p>
2316 <p>At times, authors may want selectors to describe an element that is
2317 the descendant of another element in the document tree (e.g., "an
2318 <code>EM</code> element that is contained within an <code>H1</code>
2319 element"). Descendant combinators express such a relationship. A
2321 separates two sequences of simple selectors. A selector of the form
2331 description of the following fragment:</p>
2338 either side of the "*" is not part of the universal selector; the
2339 whitespace is a combinator indicating that the DIV must be the
2340 ancestor of some element, and that that element must be an ancestor
2341 of the P.</p>
2342 <p>The following selector, which combines descendant combinators and
2347 </div>
2352 between two elements. A child combinator is made of the
2354 separates two sequences of simple selectors.
2362 <p>The following example combines descendant combinators and child
2363 combinators.</p>
2370 </div>
2372 <p>For information on selecting the first child of an element, please
2373 see the section on the <code><a
2375 above.</p>
2379 <p>There are two different sibling combinators: the adjacent sibling
2380 combinator and the general sibling combinator. In both cases,
2381 non-element nodes (e.g. text between elements) are ignored when
2382 considering adjacency of elements.</p>
2388 sequences of simple selectors. The elements represented by the two
2389 sequences share the same parent in the document tree and the element
2390 represented by the first sequence immediately precedes the element
2391 represented by the second one.</p>
2398 <p>The following selector is conceptually similar to the one in the
2399 previous example, except that it adds an attribute selector — it
2403 </div>
2410 simple selectors. The elements represented by the two sequences share
2411 the same parent in the document tree and the element represented by
2412 the first sequence precedes (not necessarily immediately) the element
2413 represented by the second one.</p>
2419 is a correct and valid, but partial, description of:</p>
2423 </div>
2429 <ul>
2431 <li>count the number of class selectors, attributes selectors, and pseudo-classes in the selector (= b)</li>
2434 </ul>
2437 are counted like any other, but the negation itself does not count as
2438 a pseudo-class.</p>
2440 <p>Concatenating the three numbers a-b-c (in a number system with a
2441 large base) gives the specificity.</p>
2454 </pre>
2455 </div>
2465 <p>The grammar below defines the syntax of Selectors. It is globally
2467 it directly, since it doesn't express the parsing conventions). The
2468 format of the productions is optimized for human consumption and some
2470 are used:</p>
2472 <ul>
2478 </ul>
2482 <pre>selectors_group
2483 : selector [ COMMA S* selector ]*
2484 ;
2486 selector
2487 : simple_selector_sequence [ combinator simple_selector_sequence ]*
2488 ;
2490 combinator
2491 /* combinators can be surrounded by white space */
2492 : PLUS S* | GREATER S* | TILDE S* | S+
2493 ;
2495 simple_selector_sequence
2496 : [ type_selector | universal ]
2497 [ HASH | class | attrib | pseudo | negation ]*
2498 | [ HASH | class | attrib | pseudo | negation ]+
2499 ;
2501 type_selector
2502 : [ namespace_prefix ]? element_name
2503 ;
2505 namespace_prefix
2506 : [ IDENT | '*' ]? '|'
2507 ;
2509 element_name
2510 : IDENT
2511 ;
2513 universal
2514 : [ namespace_prefix ]? '*'
2515 ;
2517 class
2518 : '.' IDENT
2519 ;
2521 attrib
2522 : '[' S* [ namespace_prefix ]? IDENT S*
2523 [ [ PREFIXMATCH |
2524 SUFFIXMATCH |
2525 SUBSTRINGMATCH |
2526 '=' |
2527 INCLUDES |
2528 DASHMATCH ] S* [ IDENT | STRING ] S*
2529 ]? ']'
2530 ;
2532 pseudo
2533 /* '::' starts a pseudo-element, ':' a pseudo-class */
2534 /* Exceptions: :first-line, :first-letter, :before and :after. */
2535 /* Note that pseudo-elements are restricted to one per selector and */
2536 /* occur only in the last simple_selector_sequence. */
2537 : ':' ':'? [ IDENT | functional_pseudo ]
2538 ;
2540 functional_pseudo
2541 : FUNCTION S* expression ')'
2542 ;
2544 expression
2545 /* In CSS3, the expressions are identifiers, strings, */
2546 /* or of the form "an+b" */
2547 : [ [ PLUS | '-' | DIMENSION | NUMBER | STRING | IDENT ] S* ]+
2548 ;
2550 negation
2551 : NOT S* negation_arg S* ')'
2552 ;
2554 negation_arg
2555 : type_selector | universal | HASH | class | attrib | pseudo
2556 ;</pre>
2563 case-insensitive.</p>
2566 number that current versions of Flex can deal with (decimal 255). They
2571 <pre>%option case-insensitive
2573 ident [-]?{nmstart}{nmchar}*
2574 name {nmchar}+
2575 nmstart [_a-z]|{nonascii}|{escape}
2578 escape {unicode}|\\[^\n\r\f0-9a-f]
2579 nmchar [_a-z0-9-]|{nonascii}|{escape}
2581 string {string1}|{string2}
2583 string2 \'([^\n\r\f\\']|\\{nl}|{nonascii}|{escape})*\'
2584 invalid {invalid1}|{invalid2}
2586 invalid2 \'([^\n\r\f\\']|\\{nl}|{nonascii}|{escape})*
2587 nl \n|\r\n|\r|\f
2588 w [ \t\r\n\f]*
2590 %%
2592 [ \t\r\n\f]+ return S;
2599 {ident} return IDENT;
2600 {string} return STRING;
2602 {num} return NUMBER;
2609 @{ident} return ATKEYWORD;
2610 {invalid} return INVALID;
2611 {num}% return PERCENTAGE;
2612 {num}{ident} return DIMENSION;
2618 U\+[0-9a-f?]{1,6}(-[0-9a-f]{1,6})? return UNICODE_RANGE;
2620 \/\*[^*]*\*+([^/*][^*]*\*+)*\/ /* ignore comments */
2622 . return *yytext;</pre>
2626 <h2><a name=downlevel>11. Namespaces and down-level clients</a></h2>
2628 <p>An important issue is the interaction of CSS selectors with XML
2629 documents in web clients that were produced prior to this
2630 document. Unfortunately, due to the fact that namespaces must be
2631 matched based on the URI which identifies the namespace, not the
2632 namespace prefix, some mechanism is required to identify namespaces in
2633 CSS by their URI as well. Without such a mechanism, it is impossible
2634 to construct a CSS style sheet which will properly match selectors in
2635 all cases against a random set of XML documents. However, given
2636 complete knowledge of the XML document to which a style sheet is to be
2637 applied, and a limited use of namespaces within the XML document, it
2638 is possible to construct a style sheet in which selectors would match
2639 elements and attributes correctly.</p>
2641 <p>It should be noted that a down-level CSS client will (if it
2642 properly conforms to CSS forward compatible parsing rules) ignore all
2643 <code>@namespace</code> at-rules, as well as all style rules that make
2644 use of namespace qualified element type or attribute selectors. The
2645 syntax of delimiting namespace prefixes in CSS was deliberately chosen
2646 so that down-level CSS clients would ignore the style rules rather
2647 than possibly match them incorrectly.</p>
2649 <p>The use of default namespaces in CSS makes it possible to write
2650 element type selectors that will function in both namespace aware CSS
2651 clients as well as down-level clients. It should be noted that
2652 down-level clients may incorrectly match selectors against XML
2653 elements in other namespaces.</p>
2655 <p>The following are scenarios and examples in which it is possible to
2656 construct style sheets which would function properly in web clients
2657 that do not implement this proposal.</p>
2659 <ol>
2660 <li>
2662 <p>The XML document does not use namespaces.</p>
2664 <ul>
2666 <li>In this case, it is obviously not necessary to declare or use
2667 namespaces in the style sheet. Standard CSS element type and
2668 attribute selectors will function adequately in a down-level
2669 client.</li>
2671 <li>In a CSS namespace aware client, the default behavior of
2672 element selectors matching without regard to namespace will
2673 function properly against all elements, since no namespaces are
2674 present. However, the use of specific element type selectors that
2676 will guarantee that selectors will match only XML elements that do
2677 not have a declared namespace. </li>
2679 </ul>
2681 </li>
2683 <li>
2685 <p>The XML document defines a single, default namespace used
2686 throughout the document. No namespace prefixes are used in element
2687 names.</p>
2689 <ul>
2691 <li>In this case, a down-level client will function as if
2692 namespaces were not used in the XML document at all. Standard CSS
2693 element type and attribute selectors will match against all
2694 elements. </li>
2696 </ul>
2698 </li>
2700 <li>
2702 <p>The XML document does <b>not</b> use a default namespace, all
2703 namespace prefixes used are known to the style sheet author, and
2704 there is a direct mapping between namespace prefixes and namespace
2705 URIs. (A given prefix may only be mapped to one namespace URI
2706 throughout the XML document; there may be multiple prefixes mapped
2707 to the same URI).</p>
2709 <ul>
2711 <li>In this case, the down-level client will view and match
2712 element type and attribute selectors based on their fully
2713 qualified name, not the local part as outlined in the <a
2716 to describe the fully qualified names, e.g.
2718 <code><html:h1></code>. Selectors using the qualified name
2719 will only match XML elements that use the same prefix. Other
2720 namespace prefixes used in the XML that are mapped to the same URI
2721 will not match as expected unless additional CSS style rules are
2722 declared for them.</li>
2724 <li>Note that selectors declared in this fashion will
2725 <em>only</em> match in down-level clients. A CSS namespace aware
2726 client will match element type and attribute selectors based on
2727 the name's local part. Selectors declared with the fully
2728 qualified name will not match (unless there is no namespace prefix
2729 in the fully qualified name).</li>
2731 </ul>
2733 </li>
2735 </ol>
2737 <p>In other scenarios: when the namespace prefixes used in the XML are
2738 not known in advance by the style sheet author; or a combination of
2739 elements with no namespace are used in conjunction with elements using
2740 a default namespace; or the same namespace prefix is mapped to
2741 <em>different</em> namespace URIs within the same document, or in
2742 different documents; it is impossible to construct a CSS style sheet
2743 that will function properly against all elements in those documents,
2744 unless, the style sheet is written using a namespace URI syntax (as
2745 outlined in this document or similar) and the document is processed by
2746 a CSS and XML namespace aware client.</p>
2748 <h2><a name=profiling>12. Profiles</a></h2>
2750 <p>Each specification using Selectors must define the subset of W3C
2751 Selectors it allows and excludes, and describe the local meaning of
2752 all the components of that subset.</p>
2754 <p>Non normative examples:
2758 <tbody>
2759 <tr>
2761 <tr>
2762 <th>Specification</th>
2763 <td>CSS level 1</td></tr>
2764 <tr>
2765 <th>Accepts</th>
2766 <td>type selectors<br>class selectors<br>ID selectors<br>:link,
2767 :visited and :active pseudo-classes<br>descendant combinator
2768 <br>::first-line and ::first-letter pseudo-elements</td></tr>
2769 <tr>
2770 <th>Excludes</th>
2771 <td>
2773 <p>universal selector<br>attribute selectors<br>:hover and :focus
2774 pseudo-classes<br>:target pseudo-class<br>:lang() pseudo-class<br>all UI
2775 element states pseudo-classes<br>all structural
2776 pseudo-classes<br>negation pseudo-class<br>all
2777 UI element fragments pseudo-elements<br>::before and ::after
2778 pseudo-elements<br>child combinators<br>sibling combinators
2780 <p>namespaces</td></tr>
2781 <tr>
2782 <th>Extra constraints</th>
2783 <td>only one class selector allowed per sequence of simple
2784 selectors</td></tr></tbody></table><br><br>
2786 <tbody>
2787 <tr>
2789 <tr>
2790 <th>Specification</th>
2791 <td>CSS level 2</td></tr>
2792 <tr>
2793 <th>Accepts</th>
2794 <td>type selectors<br>universal selector<br>attribute presence and
2795 values selectors<br>class selectors<br>ID selectors<br>:link, :visited,
2796 :active, :hover, :focus, :lang() and :first-child pseudo-classes
2797 <br>descendant combinator<br>child combinator<br>adjacent sibling
2798 combinator<br>::first-line and ::first-letter pseudo-elements<br>::before
2799 and ::after pseudo-elements</td></tr>
2800 <tr>
2801 <th>Excludes</th>
2802 <td>
2804 <p>content selectors<br>substring matching attribute
2805 selectors<br>:target pseudo-classes<br>all UI element
2806 states pseudo-classes<br>all structural pseudo-classes other
2807 than :first-child<br>negation pseudo-class<br>all UI element
2808 fragments pseudo-elements<br>general sibling combinators
2810 <p>namespaces</td></tr>
2811 <tr>
2812 <th>Extra constraints</th>
2813 <td>more than one class selector per sequence of simple selectors (CSS1
2814 constraint) allowed</td></tr></tbody></table>
2816 <p>In CSS, selectors express pattern matching rules that determine which style
2817 rules apply to elements in the document tree.
2819 <p>The following selector (CSS level 2) will <b>match</b> all anchors <code>a</code>
2820 with attribute <code>name</code> set inside a section 1 header <code>h1</code>:
2821 <pre>h1 a[name]</pre>
2823 <p>All CSS declarations attached to such a selector are applied to elements
2824 matching it. </div>
2828 <tbody>
2829 <tr>
2831 <tr>
2832 <th>Specification</th>
2833 <td>STTS 3</td>
2834 </tr>
2835 <tr>
2836 <th>Accepts</th>
2837 <td>
2839 <p>type selectors<br>universal selectors<br>attribute selectors<br>class
2840 selectors<br>ID selectors<br>all structural pseudo-classes<br>
2841 all combinators
2843 <p>namespaces</td></tr>
2844 <tr>
2845 <th>Excludes</th>
2846 <td>non-accepted pseudo-classes<br>pseudo-elements<br></td></tr>
2847 <tr>
2848 <th>Extra constraints</th>
2849 <td>some selectors and combinators are not allowed in fragment
2850 descriptions on the right side of STTS declarations.</td></tr></tbody></table>
2851 <form>
2877 </form>
2879 <p>Selectors can be used in STTS 3 in two different
2880 manners:
2881 <ol>
2882 <li>a selection mechanism equivalent to CSS selection mechanism: declarations
2883 attached to a given selector are applied to elements matching that selector,
2884 <li>fragment descriptions that appear on the right side of declarations.
2885 </li></ol></div>
2887 <h2><a name=Conformance></a>13. Conformance and requirements</h2>
2889 <p>This section defines conformance with the present specification only.
2891 <p>The inability of a user agent to implement part of this specification due to
2892 the limitations of a particular device (e.g., non interactive user agents will
2893 probably not implement dynamic pseudo-classes because they make no sense without
2894 interactivity) does not imply non-conformance.
2896 <p>All specifications reusing Selectors must contain a <a
2898 subset of Selectors it accepts or excludes, and describing the constraints
2899 it adds to the current specification.
2901 <p>Invalidity is caused by a parsing error, e.g. an unrecognized token or a token
2902 which is not allowed at the current parsing point.
2904 <p>User agents must observe the rules for handling parsing errors:
2905 <ul>
2906 <li>a simple selector containing an undeclared namespace prefix is invalid</li>
2907 <li>a selector containing an invalid simple selector, an invalid combinator
2908 or an invalid token is invalid. </li>
2909 <li>a group of selectors containing an invalid selector is invalid.</li>
2910 </ul>
2913 errors. (In the case of CSS, the entire rule in which the selector is
2914 used is dropped.)</p>
2916 <!-- Apparently all these references are out of date:
2917 <p>Implementations of this specification must behave as
2919 when parsing selectors and attempting matches. (In particular,
2920 implementations must assume the data is normalized and must not
2921 normalize it.) Normative rules for matching strings are defined in
2924 specification.</p>-->
2926 <h2><a name=Tests></a>14. Tests</h2>
2928 <p>This specification has <a
2930 suite</a> allowing user agents to verify their basic conformance to
2931 the specification. This test suite does not pretend to be exhaustive
2932 and does not cover all possible combined cases of Selectors.</p>
2934 <h2><a name=ACKS></a>15. Acknowledgements</h2>
2936 <p>The CSS working group would like to thank everyone who has sent
2937 comments on this specification over the years.</p>
2939 <p>The working group would like to extend special thanks to Donna
2940 McManus, Justin Baker, Joel Sklar, and Molly Ives Brower who perfermed
2941 the final editorial review.</p>
2943 <h2><a name=references>16. References</a></h2>
2947 <dt>[CSS1]
2948 <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
2951 <dt>[CSS21]
2952 <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
2955 <dt>[CWWW]
2956 <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
2959 <dt>[FLEX]
2960 <dd><a name="refsFLEX"></a> "<cite>Flex: The Lexical Scanner Generator</cite>", Version 2.3.7, ISBN 1882114213
2962 <dt>[HTML4]
2963 <dd><a name="refsHTML4"></a> Dave Ragget, Arnaud Le Hors, Ian Jacobs, editors; "<cite>HTML 4.01 Specification</cite>", W3C Recommendation, 24 December 1999
2966 <dt>[MATH]
2967 <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
2968 <dd>(<code><a href="http://www.w3.org/TR/REC-MathML/">http://www.w3.org/TR/REC-MathML/</a></code>)
2970 <dt>[RFC3066]
2971 <dd><a name="refsRFC3066"></a> H. Alvestrand; "<cite>Tags for the Identification of Languages</cite>", Request for Comments 3066, January 2001
2972 <dd>(<a href="http://www.ietf.org/rfc/rfc3066.txt"><code>http://www.ietf.org/rfc/rfc3066.txt</code></a>)
2974 <dt>[STTS]
2975 <dd><a name=refsSTTS></a> Daniel Glazman; "<cite>Simple Tree Transformation Sheets 3</cite>", Electricité de France, submission to the W3C, 11 November 1998
2976 <dd>(<code><a href="http://www.w3.org/TR/NOTE-STTS3">http://www.w3.org/TR/NOTE-STTS3</a></code>)
2978 <dt>[SVG]
2979 <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
2982 <dt>[UNICODE]</dt>
2984 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>.
2985 <dd>(<code><a href="http://www.unicode.org/versions/">http://www.unicode.org/versions/</a></code>)</dd>
2987 <dt>[XML10]
2988 <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
2991 <dt>[XMLNAMES]
2992 <dd><a name="refsXMLNAMES"></a> Tim Bray, Dave Hollander, Andrew Layman, editors; "<cite>Namespaces in XML</cite>", W3C Recommendation, 14 January 1999
2993 <dd>(<a href="http://www.w3.org/TR/REC-xml-names/"><code>http://www.w3.org/TR/REC-xml-names/</code></a>)
2995 <dt>[YACC]
2996 <dd><a name="refsYACC"></a> S. C. Johnson; "<cite>YACC — Yet another compiler compiler</cite>", Technical Report, Murray Hill, 1975
2998 </dl>
2999 </body>
3000 </html>