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revision 1.20 by wakaba, Sun May 18 07:24:04 2008 UTC revision 1.37 by wakaba, Wed Sep 10 10:22:59 2008 UTC
# Line 1  Line 1 
1  <!DOCTYPE html><html id="error-description" lang="en" xmlns:d="http://suika.fam.cx/~wakaba/archive/2007/wdcc-desc/" xmlns="http://www.w3.org/1999/xhtml">  <!DOCTYPE html><html id="error-description" lang="en" xmlns:d="http://suika.fam.cx/~wakaba/archive/2007/wdcc-desc/" xmlns="http://www.w3.org/1999/xhtml">
2  <head>  <head>
3  <title xml:lang="en">Description of Errors —  <base href="cc/">
4  Web Document Conformance Checker (BETA)</title>  
5  <link href="cc-style" rel="stylesheet">  
6    <link href="../cc-style" rel="stylesheet">
7  <link href="#license" rel="license">  <link href="#license" rel="license">
8  </head>  <title xml:lang="en">Description of Errors — WebHACC (β)</title></head>
9  <body>  <body>
10  <h1>Description of Errors</h1>  <header>
11    <h1><a href="../cc-about"><abbr title="Web Hypertext Application Conformance Checker (β)"><img alt="WebHACC" src="../icons/title"></abbr></a></h1>
12    <h2>Description of Errors</h2>
13    </header>
14    
15    
16    
17    <div class="section" id="WebHACC:Heading"><h3>
18        
19      </h3>
20        <p><a href="./#input"><abbr title="Web Hypertext Application Conformance Checker">WebHACC</abbr></a>
21        is a <em>conformance checker</em> (or validator) for Web documents,
22        supporting <a href="../standards">latest Web standards</a> including
23        <a href="http://whatwg.org/html5"><abbr title="Hypertext Markup Language">HTML</abbr>5</a>,
24        <a href="urn:ietf:rfc:4287">Atom 1.0</a>,
25        <a href="http://www.w3.org/Style/CSS/current-work"><abbr title="Cascading Style Sheets">CSS</abbr>3</a>.</p>
26    
27        <p><strong><a href="./#input">Check your document</a></strong>, or
28        <a href="../cc-about">learn more about
29        <abbr title="Web Hypertext Application Conformance Checker">WebHACC</abbr></a>.</p>
30      </div>
31    
32  <section id="character-encoding-layer">  <section id="character-encoding-layer">
33  <h2>Character Encoding Layer Errors</h2>  <h2>Character Encoding Layer Errors</h2>
34    
35  <div class="section error-category-charset" id="m:illegal-octets-error"><h3>An illegal octet in the input stream.</h3></div>  <div class="section" id="fallback-char-error"><h3>Octet sequence <code><var>{octets}</var></code>
36      is not an allowed representation of the character
37      <code><var>{char}</var></code> — character reference
38      <code><var>{char:hexref}</var></code> should be used instead.</h3></div>
39    
40    <div class="section" id="fallback-unassigned-error"><h3>No character is assigned to octet sequence
41      <code><var>{octets}</var></code>.</h3></div>
42    
43    <div class="section" id="illegal-octets-error"><h3>Octet sequence <code><var>{octets}</var></code>
44      is illegal.</h3></div>
45    
46    <div class="section" id="invalid-state-error"><h3>The input stream is broken.</h3>
47        <p>The input stream is encoded in <code>ISO-2022-JP</code>
48        or its variant but is partially broken.</p>
49    
50        <p>Note that an <code>ISO-2022-JP</code> stream must end in the ASCII
51        state.</p>
52      </div>
53    
54    <div class="section" id="unassigned-code-point-error"><h3>No character is assigned to octet sequence
55      <code><var>{octets}</var></code>.</h3></div>
56  </section>  </section>
57    
58  <section id="html5-character-encoding">  <section id="html5-character-encoding">
59  <h2>HTML5 Character Encoding Errors</h2>  <h2>HTML5 Character Encoding Errors</h2>
60    
61  <div class="section format-charset must" id="m:character-encoding"><h3>Character encoding <code><var>$0</var></code>  <div class="section" id="disallowed-character-encoding"><h3>Character encoding <code><var>{text}</var></code>
62    is not allowed for <abbr>HTML</abbr> document.</h3>    is not allowed for <abbr>HTML</abbr> document.</h3>
63      <p>The character encoding used for the document is not allowed      <p>The character encoding used for the document is not allowed
64      for <abbr>HTML</abbr> document.  The document is non‐conforming.</p>      for <abbr>HTML</abbr> document.  The document is non‐conforming.</p>
65    </div>    </div>
66    
67  <div class="section format-charset should" id="s:character-encoding"><h3>Character encoding <code><var>$0</var></code>  <div class="section" id="bad-character-encoding"><h3>Character encoding <code><var>{text}</var></code>
68    should not be used for <abbr>HTML</abbr> document.</h3>    should not be used for <abbr>HTML</abbr> document.</h3>
69      <p>The character encoding used for the document is not recommended      <p>The character encoding used for the document is not recommended
70      for <abbr>HTML</abbr> document.  The document is non‐conforming      for <abbr>HTML</abbr> document.  The document is non‐conforming
71      unless there is any good reason to use that encoding.</p>      unless there is any good reason to use that encoding.</p>
72    </div>    </div>
73    
74  <div class="section format-charset warning" id="w:character-encoding"><h3>Use of UTF-8 is encouraged.</h3>  <div class="section" id="non-utf-8-character-encoding"><h3>Use of UTF-8 is encouraged (this document
75      is encoded in <code><var>{text}</var></code>).</h3>
76      <p>Use of UTF-8 as the character encoding of the document is encouraged,      <p>Use of UTF-8 as the character encoding of the document is encouraged,
77      though the use of another character encoding is still conforming.</p>      though the use of another character encoding is still conforming.</p>
78    </div>    </div>
79    
80  <div class="section format-charset unsupported" id="unsupported:character-encoding"><h3>Conformance for character encoding requirements  <div class="section" id="character-encoding-unchecked"><h3>Conformance for character encoding requirements
81    cannot be checked.</h3>    cannot be checked, since the input is not a byte stream.</h3>
82      <p>The conformance checker cannot detect whether the input document      <p>The conformance checker cannot detect whether the input document
83      met the requirements on character encoding, since the document      met the requirements on character encoding, since the document
84      is not inputed as a serialized byte sequence.  The document is      is not inputed as a serialized byte sequence.  The document is
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86      encoding with appropriate labeling.</p>      encoding with appropriate labeling.</p>
87    </div>    </div>
88    
89  <div class="section format-charset error" id="m:no-character-encoding-declaration"><h3>There is no character encoding  <div class="section" id="no-character-encoding-declaration"><h3>There is no character encoding
90    declaration.</h3>    declaration.</h3>
91      <p>The document does not contain a character encoding      <p>The document does not contain a character encoding
92      declaration.  Unless the character encoding is explicitly      declaration.  Unless the character encoding is explicitly
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95      encoding declaration.  The document is non‐conforming.</p>      encoding declaration.  The document is non‐conforming.</p>
96    
97      <p>The long character encoding declaration syntax      <p>The long character encoding declaration syntax
98      <code class="html bad example">&lt;meta http-equiv=&quot;Content-Type&quot; content=&quot;text/html; charset=<var>charset-name</var>&quot;&gt;</code>      <code class="html bad example">&lt;meta http-equiv="Content-Type" content="text/html; charset=<var>charset-name</var>"&gt;</code>
99      is obsolete.  The new syntax is:</p>      is obsolete.  The new syntax is:</p>
100      <pre class="html example">      <pre class="html example">
101  <code>&lt;meta charset=&quot;<var>charset-name</var>&quot;&gt;</code></pre>  <code>&lt;meta charset="<var>charset-name</var>"&gt;</code></pre>
102    
103      <p>Note that the <code>encoding</code> declaration in <abbr>XML</abbr>      <p>Note that the <code>encoding</code> declaration in <abbr>XML</abbr>
104      declaration has no effect for <abbr>HTML</abbr> document.</p>      declaration has no effect for <abbr>HTML</abbr> document.</p>
105    </div>    </div>
106    
107  <div class="section format-charset error" id="m:non-ascii-superset"><h3>No character encoding metadata is found  <div class="section" id="non-ascii-superset"><h3>No character encoding metadata is found
108    in lower‐level protocol nor is there <abbr>BOM</abbr>, while    in lower‐level protocol nor is there <abbr>BOM</abbr>, while
109    character encoding <code><var>$0</var></code>    character encoding <code><var>{text}</var></code>
110    is not a superset of <abbr>ASCII</abbr>.</h3>    is not a superset of <abbr>ASCII</abbr>.</h3>
111      <p>The document is not labeled with character encoding name      <p>The document is not labeled with character encoding name
112      in lower‐level protocol, e.g. in <abbr>HTTP</abbr>, and      in lower‐level protocol, e.g. in <abbr>HTTP</abbr>, and
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121  <code>Content-Type: text/html; charset=<var>charset-name</var></code></pre>  <code>Content-Type: text/html; charset=<var>charset-name</var></code></pre>
122    
123      <p>Existence of <abbr>HTML</abbr> character encoding declaration, i.e.      <p>Existence of <abbr>HTML</abbr> character encoding declaration, i.e.
124      <code class="html example">&lt;meta charset=&quot;<var>charset-name</var>&quot;&gt;</code>,      <code class="html example">&lt;meta charset="<var>charset-name</var>"&gt;</code>,
125      does not allow to omit <code>charset</code> parameter      does not allow to omit <code>charset</code> parameter
126      for <abbr>HTML</abbr> document encoded in non‐<abbr>ASCII</abbr>      for <abbr>HTML</abbr> document encoded in non‐<abbr>ASCII</abbr>
127      compatible encoding.</p>      compatible encoding.</p>
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131      <abbr>ASCII</abbr> for the purpose of <abbr>HTML</abbr> conformance.</p>      <abbr>ASCII</abbr> for the purpose of <abbr>HTML</abbr> conformance.</p>
132    </div>    </div>
133    
134  <div class="section format-charset warning" id="w:charset-label-detected"><h3>While parsing the document as  <div class="section" id="sniffing:chardet"><h3>Character encoding of this document is sniffed
135    <code><var>$0</var></code>, a character encoding declaration specifying    as <code><var>{text}</var></code> (Sniffed because no explicit specification
136    character encoding as <code><var>$1</var></code> is found.  The document    for the character encoding of this document is found in the transfer
137      procotol headers).</h3></div>
138    
139    <div class="section" id="sniffing:default"><h3>Character encoding of this document is defaulted
140      to <code><var>{text}</var></code> because no explicit specification
141      for the character encoding of this document is found in the transfer
142      procotol headers.</h3></div>
143    
144    <div class="section" id="chardecode:fallback"><h3>Results might be <em>wrong</em>, since the
145      conformance checker cannot find an appropriate decoder for the character
146      encoding used for the document.</h3>
147        <p>The conformance checker cannot find an appropriate decoder for
148        the character encoding used to encode characters in the document.</p>
149    
150        <p>This error is raised if:</p>
151        <ul>
152        <li>the conformance checker cannot find any decoder for the character
153        encoding in use, but it knows that the encoding is similar to another
154        character encoding, such that it uses the decoder for that character
155        encoding, and therefore some octets might be interpreted incorrectly,
156        or,</li>
157        <li>the conformance checker find a decoder for the character encoding
158        in use, but it does not know whether the decoder is conforming to the
159        relevant specification or not, and therefore some octets might be
160        interpreted incorrectly.</li>
161        </ul>
162    
163        <p>In either case, the result shown by the conformance checker might
164        contain wrong errors caused by errorneous decoder or might not contain
165        errors that should be raised if an appropriate decoder is used.</p>
166    
167        <!-- TODO: add advise that either install relevant modules or
168             join the developmenet of the modules... -->
169      </div>
170    
171    <div class="section" id="chardecode:no-error"><h3>Conformance error checking for the character
172      encoding <code><var>{text}</var></code> is not supported.</h3></div>
173    
174    <div class="section" id="charset-label:matching"><h3>Sniffed character encoding
175      <code><var>{text}</var></code> is same as the character encoding specified
176      in the character encoding declaration.  This is <em>not</em> an
177      error.</h3></div>
178    
179    <div class="section" id="charset-label-detected"><h3>While parsing the document as
180      <code><var>{text}</var></code>, a character encoding declaration specifying
181      a different character encoding is found.  The document
182    is reparsed.</h3>    is reparsed.</h3>
183      <p>While parsing a document in a character encoding,      <p>While parsing a document in a character encoding,
184      a character encoding declaration which declares the character      a character encoding declaration which declares the character
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196      <li>Specify <code>charset</code> parameter in the <code>Content-Type</code>      <li>Specify <code>charset</code> parameter in the <code>Content-Type</code>
197      field in the <abbr>HTTP</abbr> header, as:      field in the <abbr>HTTP</abbr> header, as:
198      <pre class="HTTP example">      <pre class="HTTP example">
199  <code>Content-Type: text/html; charset=&quot;<var>charset-name</var>&quot;</code></pre></li>  <code>Content-Type: text/html; charset="<var>charset-name</var>"</code></pre></li>
200      <li>Put the character encoding declaration      <li>Put the character encoding declaration
201      (<code class="html example">&lt;meta charset=&quot;<var>charset-name</var>&quot;&gt;</code>)      (<code class="html example">&lt;meta charset="<var>charset-name</var>"&gt;</code>)
202      just after <code class="html example">&lt;head&gt;</code> start tag.</li>      just after <code class="html example">&lt;head&gt;</code> start tag.</li>
203      <li>Use <code>UTF-8</code>.</li>      <li>Use <code>UTF-8</code>.</li>
204      </ul>      </ul>
205    </div>    </div>
206    
207    <div class="section" id="NULL"><h3>The <code class="charname">NULL</code> character
208      is not allowed.</h3></div>
209    
210    <div class="section" id="control-char"><h3>Code point <code><var>{text}</var></code> is
211      not allowed.</h3></div>
212    
213  </section>  </section>
214    
215  <section id="html5-tokenize-error">  <section id="html5-tokenize-error">
216  <h2>HTML5 Parse Errors in Tokenization Stage</h2>  <h2>HTML5 Parse Errors in Tokenization Stage</h2>
217    
218  <div class="section parse-error" id="after-html"><h3>Tag <code>&lt;<var>$0</var>&gt;</code>  <div class="section" id="bad-attribute-name"><h3>Attribute name cannot contain characters
219    is not allowed after the end tag <code>&lt;/html&gt;</code>.</h3>    <code>"</code>, <code>'</code>, and <code>=</code>.</h3></div>
     <p>The start or end tag of an element appears after the  
     <code>html</code> element has been closed.  The document is  
     non-conforming.</p>  
   
     <p>Any content of the document other than comments  
     must be put into the <code>html</code> element.</p>  
   </div>  
   
 <div class="section parse-error" id="after-body"><h3>Tag <code>&lt;<var>$0</var>&gt;</code>  
   is not allowed after the end tag <code>&lt;/body&gt;</code>.</h3>  
     <p>The start or end tag of an element appears after the  
     <code>body</code> element has been closed.  The document is  
     non-conforming.</p>  
220    
221      <p>Any content of the document other than <code>head</code>  <div class="section" id="bad-attribute-value"><h3>Attribute value must be quoted by <code>"</code>
222      contents and comments must be put into the <code>body</code>    or <code>'</code> if it contains a <code>"</code>, <code>'</code>, or
223      element.</p>    <code>=</code> character.</h3>
224        <p>In an unquoted attribute value, a character <code>"</code>
225        (<code>U+0022</code> <code class="charname">QUOTATION MARK</code>),
226        <code>'</code> (<code>U+0026</code>
227        <code class="charname">APOSTROPHE</code>), or <code>=</code>
228        (<code>U+003D</code> <code class="charname">EQUAL SIGN</code>)
229        is contained.  These characters are not allowed in unquoted attribute
230        values, since they are used to quote attribute values or to separate
231        attribute name and value.</p>
232    
233        <p>This error is also raised if one try to use empty attribute
234        value like <code class="html bad example">&lt;foo bar= baz=&gt;</code>;
235        in this example, <code class="html bad example">baz=</code> is
236        treated as an invalid attribute value for the attribute
237        <code class="html bad example">bar</code>, not as another attribute.</p>
238    </div>    </div>
239    
240  <div class="section tokenize-error" id="bare-ero"><h3>The <code>&amp;</code> character must  <div class="section" id="bare-ero"><h3>The <code>&amp;</code> character must
241    be escaped as <code class="html example">&amp;amp;</code>.</h3>    be escaped as <code class="html example">&amp;amp;</code>.</h3>
242      <p>An <code>&amp;</code> character which      <p>An <code>&amp;</code> character which
243      is not part of any reference appears in the input stream.      is not part of any reference appears in the input stream.
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274      </p>      </p>
275    </div>    </div>
276    
277  <div class="section tokenize-error" id="bare-etago"><h3>A <code>&lt;/</code> string is not followed  <div class="section" id="bare-etago"><h3>A <code>&lt;/</code> string is not followed
278    by a tag name.</h3>    by a tag name.</h3>
279      <p>There is a <code>&lt;</code> (<code>U+003C</code>      <p>There is a <code>&lt;</code> (<code>U+003C</code>
280      <code class="charname">LESS-THAN SIGN</code>) character      <code class="charname">LESS-THAN SIGN</code>) character
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294      </p>      </p>
295    </div>    </div>
296    
297  <div class="section tokenize-error" id="bare-stago"><h3>A <code>&lt;</code> character is not followed  <div class="section" id="bare-stago"><h3>A <code>&lt;</code> character is not followed
298    by tag name or by a <code>!</code> character.</h3>    by tag name or by a <code>!</code> character.</h3>
299      <p>A <code>&lt;</code> (<code>U+003C</code>      <p>A <code>&lt;</code> (<code>U+003C</code>
300      <code class="charname">LESS-THAN SIGN</code>) character which is not part      <code class="charname">LESS-THAN SIGN</code>) character which is not part
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307      </p>      </p>
308    </div>    </div>
309    
310  <div class="section tokenize-error" id="bare-nero"><h3>The decimal representation of the code position  <div class="section" id="bare-nero"><h3>The decimal representation of the code position
311    of a character must be specified after <code>&amp;#</code>.</h3>    of a character must be specified after <code>&amp;#</code>.</h3>
312      <p>An <code>&amp;</code> (<code>U+0026</code>      <p>An <code>&amp;</code> (<code>U+0026</code>
313      <code class="charname">AMPERSAND</code>) character immediately      <code class="charname">AMPERSAND</code>) character immediately
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339      </p>      </p>
340    </div>    </div>
341    
342  <div class="section tokenize-error" id="bare-hcro"><h3>The hexadecimal representation of the code position  <div class="section" id="bare-hcro"><h3>The hexadecimal representation of the code position
343    of a character must be specified after <code>&amp;#x</code>.</h3>    of a character must be specified after <code>&amp;#x</code>.</h3>
344     <p>The string <code>&amp;#x</code> or <code>&amp;#X</code> which     <p>The string <code>&amp;#x</code> or <code>&amp;#X</code> which
345     is not part of any reference appears in the input stream.     is not part of any reference appears in the input stream.
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359      </p>      </p>
360    </div>    </div>
361    
362  <div class="section tokenize-error" id="bogus-comment"><h3>String <code>&lt;!</code> is not followed  <div class="section" id="bogus-comment"><h3>String <code>&lt;!</code> is not followed
363    by <code>--</code>.</h3>    by <code>--</code>.</h3>
364      <p>There is a <code>&lt;</code> (<code>U+003C</code>      <p>There is a <code>&lt;</code> (<code>U+003C</code>
365      <code class="charname">LESS-THAN SIGN</code>) character      <code class="charname">LESS-THAN SIGN</code>) character
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389      </dl>      </dl>
390    </div>    </div>
391    
392  <div class="section tokenize-error" id="bogus-end-tag"><h3>String <code>&lt;/</code> is not followed  <div class="section" id="bogus-end-tag"><h3>String <code>&lt;/</code> is not followed
393    by tag name.</h3>    by tag name.</h3>
394      <p>There is a <code>&lt;</code> (<code>U+003C</code>      <p>There is a <code>&lt;</code> (<code>U+003C</code>
395      <code class="charname">LESS-THAN SIGN</code>) character      <code class="charname">LESS-THAN SIGN</code>) character
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408      </p>      </p>
409    </div>    </div>
410    
411  <div class="section tokenize-error" id="dash-in-comment"><h3>There is a <code>--</code> sequence  <div class="section" id="C1-character-reference"><h3>Character reference to
412      <code><var>{text}</var></code> is not allowed.</h3></div>
413    
414    <div class="section" id="CR-character-reference"><h3>Character reference to
415      <code>U+000D</code> (<code class="charname">CARRIAGE RETURN</code>)
416      is not allowed.</h3></div>
417    
418    <div class="section" id="dash-in-comment"><h3>There is a <code>--</code> sequence
419    in a comment.</h3>    in a comment.</h3>
420      <p>There is a <code>-</code> (<code>U+002D</code>      <p>There is a <code>-</code> (<code>U+002D</code>
421      <code class="charname">HYPHEN-MINUS</code>) character      <code class="charname">HYPHEN-MINUS</code>) character
# Line 326  Web Document Conformance Checker (BETA)< Line 428  Web Document Conformance Checker (BETA)<
428      declaration.</p>      declaration.</p>
429    </div>    </div>
430    
431  <div class="section tokenize-error" id="duplicate-attribute"><h3>There are two attributes with name  <div class="section" id="duplicate-attribute"><h3>There are two attributes with name
432        <code><var>$0</var></code>.</h3>        <code><var>{text}</var></code>.</h3>
433      <p>There are more than one attributes with the same      <p>There are more than one attributes with the same
434      name in a tag.  The document is non-conforming.</p>      name in a tag.  The document is non-conforming.</p>
435    
# Line 335  Web Document Conformance Checker (BETA)< Line 437  Web Document Conformance Checker (BETA)<
437      Use <code>img</code> element with animation GIF instead.</p>      Use <code>img</code> element with animation GIF instead.</p>
438    </div>    </div>
439    
440  <div class="section tokenize-error" id="nestc"><h3>Polytheistic slash (<code>/&gt;</code>) cannot be  <div class="section" id="empty-start-tag"><h3>Empty start tag (<code>&lt;&gt;</code>) is not
441      allowed.</h3></div>
442    
443    <div class="section" id="empty-end-tag"><h3>Empty end tag (<code>&lt;/&gt;</code>) is not
444      allowed.</h3></div>
445    
446    <div class="section" id="end-tag-attribute"><h3>End tag cannot have attributes.</h3></div>
447    
448    <div class="section" id="empty-unquoted-attribute-value"><h3>Attribute value is not specified.</h3>
449        <p>The attribute value is not specified after the <code>=</code>
450        (<code>U+003C</code> <code class="charname">EQUAL SIGN</code>)
451        character.</p>
452    
453        <p>When an attribute value is empty, the <code>=</code> character after
454        the attribute name must be specified as:</p>
455    
456        <p><code class="html example">&lt;foo bar&gt;</code></p>
457    
458        <p>Instead, quotation marks can be used to explicitly represent that
459        the attribute value is empty, as:</p>
460    
461        <p><code class="html example">&lt;foo bar=""&gt;</code></p>
462    
463        <p>... or like:</p>
464    
465        <p><code class="html example">&lt;foo bar=''&gt;</code></p>
466      </div>
467    
468    <div class="section" id="invalid-character-reference"><h3>Character reference to
469      <code><var>{text}</var></code> is not allowed.</h3></div>
470    
471    <div class="section" id="nestc"><h3>Polytheistic slash (<code>/&gt;</code>) cannot be
472    used for this element.</h3>    used for this element.</h3>
473      <p>Polytheistic slash (<code>/&gt;</code>) must not be used      <p>Polytheistic slash (<code>/&gt;</code>) must not be used
474      for the element.  The document is non-conforming.</p>      for the element.  The document is non-conforming.</p>
# Line 379  Web Document Conformance Checker (BETA)< Line 512  Web Document Conformance Checker (BETA)<
512      no effect in HTML.</p>      no effect in HTML.</p>
513    </div>    </div>
514    
515    <div class="section" id="no-DOCTYPE-name"><h3>After the string <code>&lt;!DOCTYPE </code>, the
516      document type name must be specified.</h3></div>
517    
518    <div class="section" id="no-PUBLIC-literal"><h3>After the keyword <code>PUBLIC</code>, no
519      oublic identifier is specified.</h3></div>
520    
521    <div class="section" id="no-refc"><h3>Character reference must be closed by a
522      <code>;</code> character.</h3></div>
523    
524    <div class="section" id="no-space-before-DOCTYPE-name"><h3>After the string <code>&lt;!DOCTYPE</code>, there
525      must be at least a white space character before the document type
526      name.</h3></div>
527    
528  <div class="section tokenize-error" id="pio"><h3>Processing instruction  <div class="section" id="no-space-between-attributes"><h3>Attributes must be separeted by at least a
529    (<code>&lt;?<var>...</var>&gt;</code>) cannot be used.</h3>    white space character.</h3></div>
530    
531    <div class="section" id="no-SYSTEM-literal"><h3>After the keyword <code>SYSTEM</code>, no
532      system identifier is specified.</h3></div>
533    
534    <div class="section" id="pio"><h3>Processing instruction
535      (<code>&lt;?<var>...</var>&gt;</code>) is not allowed in HTML
536      document.</h3>
537      <p>Processing instructions (<code>&lt;?<var>...</var>?&gt;</code>),      <p>Processing instructions (<code>&lt;?<var>...</var>?&gt;</code>),
538      including XML declaration (<code>&lt;?xml <var>...</var>?&gt;</code>)      including XML declaration (<code>&lt;?xml <var>...</var>?&gt;</code>)
539      and XML style sheet <abbr title="processing instruction">PI</abbr>      and XML style sheet <abbr title="processing instruction">PI</abbr>
# Line 410  p { Line 562  p {
562          <code>alternate stylesheet</code> for an alternate style          <code>alternate stylesheet</code> for an alternate style
563          sheet).          sheet).
564            <pre class="example html">            <pre class="example html">
565  <code>&lt;link rel=stylesheet href=&quot;path/to/stylesheet.css&quot;&gt;</code></pre>  <code>&lt;link rel=stylesheet href="path/to/stylesheet.css"&gt;</code></pre>
566          </dd>          </dd>
567      <dt><code>&lt;?php?&gt;</code> or      <dt><code>&lt;?php?&gt;</code> or
568      <code>&lt;? <var>... <abbr>PHP</abbr> code ...</var> ?&gt;</code>      <code>&lt;? <var>... <abbr>PHP</abbr> code ...</var> ?&gt;</code>
# Line 429  p { Line 581  p {
581      as string.</p>      as string.</p>
582    </div>    </div>
583    
584    <div class="section" id="string-after-DOCTYPE-name"><h3>There is a bogus string after the document type
585      name.</h3></div>
586    
587    <div class="section" id="string-after-PUBLIC"><h3>There is a bogus string after the keyword
588      <code>PUBLIC</code>.</h3></div>
589    
590    <div class="section" id="string-after-PUBLIC-literal"><h3>There is a bogus string after the public
591      identifier.</h3></div>
592    
593    <div class="section" id="string-after-SYSTEM"><h3>There is a bogus string after the keyword
594      <code>SYSTEM</code>.</h3></div>
595    
596    <div class="section" id="string-after-SYSTEM-literal"><h3>There is a bogus string after the system
597      identifier.</h3></div>
598    
599    <div class="section" id="unclosed-attribute-value"><h3>Attribute value is not closed by a quotation
600      mark.</h3></div>
601    
602    <div class="section" id="unclosed-comment"><h3>Comment is not closed by a string
603      <code>--&gt;</code>.</h3></div>
604    
605    <div class="section" id="unclosed-DOCTYPE"><h3>The <code>DOCTYPE</code> is not closed by a
606      <code>&gt;</code> character.</h3></div>
607    
608    <div class="section" id="unclosed-PUBLIC-literal"><h3>The public identifier literal is not closed by a
609      quotation mark.</h3></div>
610    
611    <div class="section" id="unclosed-SYSTEM-literal"><h3>The system identifier literal is not closed by a
612      quotation mark.</h3></div>
613    
614    <div class="section" id="unclosed-tag"><h3>Tag is not closed by a <code>&gt;</code>
615      character.</h3></div>
616    
617  </section>  </section>
618    
619  <section id="html5-parse-errors">  <section id="html5-parse-errors">
620  <h2>HTML5 Parse Errors in Tree Construction Stage</h2>  <h2>HTML5 Parse Errors in Tree Construction Stage</h2>
621    
622  <div class="section parse-error" id="after-head"><h3>The <code><var>$0</var></code> element cannot be  <div class="section" id="after-after-frameset"><h3>There is a start tag
623    inserted between <code>head</code> and <code>body</code> elements.</h3>    <code>&lt;<var>{text}</var>&gt;</code> is after the <code>html</code> element
624      is closed.</h3></div>
625    
626    <div class="section" id="after-after-frameset:/"><h3>There is an end tag
627      <code>&lt;/<var>{text}</var>&gt;</code> is after the <code>html</code> element
628      is closed.</h3></div>
629    
630    <div class="section" id="after-body"><h3>Start tag <code>&lt;<var>{text}</var>&gt;</code> is
631      not allowed after the <code>body</code> is closed.</h3></div>
632    
633    <div class="section" id="after-body:/"><h3>End tag <code>&lt;/<var>{text}</var>&gt;</code> is
634      not allowed after the <code>body</code> is closed.</h3></div>
635    
636    <div class="section" id="after-body:#text"><h3>Non‐white‐space characters are not allowed
637      after the <code>body</code> is closed.</h3></div>
638    
639    <div class="section" id="after-frameset"><h3>Start tag <code>&lt;<var>{text}</var>&gt;</code> is
640      not allowed after the <code>frameset</code> is closed.</h3></div>
641    
642    <div class="section" id="after-frameset:/"><h3>End tag <code>&lt;/<var>{text}</var>&gt;</code> is
643      not allowed after the <code>frameset</code> is closed.</h3></div>
644    
645    <div class="section" id="after-frameset:#text"><h3>Non‐white‐space characters are not allowed
646      after the <code>frame</code> is closed.</h3></div>
647    
648    <div class="section" id="after-head"><h3>The <code><var>{text}</var></code> element cannot be
649      inserted between <code>head</code> and <code>body</code>
650      elements.</h3>
651      <p>A start tag appears after the <code>head</code> element is closed      <p>A start tag appears after the <code>head</code> element is closed
652      but before the <code>body</code> element is opened.      but before the <code>body</code> element is opened.
653      The document is non-conforming.</p>      The document is non-conforming.</p>
654    </div>    </div>
655    
656  <div class="section parse-error" id="DOCTYPE-in-the-middle"><h3>A <code>DOCTYPE</code> appears after any  <div class="section" id="after-html"><h3>Start tag <code>&lt;<var>{text}</var>&gt;</code> is
657    element or data character has been seen.</h3>    not allowed after the <code>html</code> is closed.</h3>
658      <p>A <code>DOCTYPE</code> appears after any element or data character      <p>The start tag of an element appears after the
659      has been seen.  The document is non-conforming.</p>      <code>body</code> element has been closed.  The document is
660            non-conforming.</p>
661      <p>The <code>DOCTYPE</code> must be placed before any  
662      tag, reference, or data character.  Only white space characters      <p>Any content of the document other than <code>head</code>
663      and comments can be inserted before the <code>DOCTYPE</code>.</p>      contents and comments must be put into the <code>body</code>
664        element.</p>
665    </div>    </div>
666    
667  <div class="section parse-error" id="in-a:a"><h3>Anchor cannot be nested.</h3>  <div class="section" id="after-html:/"><h3>End tag <code>&lt;/<var>{text}</var>&gt;</code> is
668      not allowed after the <code>html</code> is closed.</h3>
669        <p>The end tag of an element appears after the
670        <code>body</code> element has been closed.  The document is
671        non-conforming.</p>
672    
673        <p>Any content of the document other than <code>head</code>
674        contents and comments must be put into the <code>body</code>
675        element.</p>
676      </div>
677    
678    <div class="section" id="after-html:#text"><h3>Non‐white‐space characters are not allowed
679      after the <code>html</code> is closed.</h3></div>
680    
681    <div class="section" id="image"><h3>The <code>image</code> element is
682      obsolete.</h3></div>
683    
684    <div class="section" id="in-a:a"><h3>Anchor cannot be nested.</h3>
685      <p>HTML <code>a</code> elements cannot be nested.      <p>HTML <code>a</code> elements cannot be nested.
686      The document is non-conforming.</p>      The document is non-conforming.</p>
687    
# Line 459  p { Line 689  p {
689      implies the end tag of any opening <code>a</code> element.</p>      implies the end tag of any opening <code>a</code> element.</p>
690    </div>    </div>
691    
692  <div class="section parse-error" id="in-body"><h3>Tag <code>&lt;<var>$0</var>&gt;</code>  <div class="section" id="in-body"><h3>Start tag <code>&lt;<var>{text}</var>&gt;</code>
693    is not allowed in the <code>body</code> element.</h3>    is not allowed in the <code>body</code> element.</h3>
694      <p>The start or end tag of an element, which      <p>The start or end tag of an element, which
695      cannot be a descendant of <code>body</code> element, appears      cannot be a descendant of <code>body</code> element, appears
# Line 467  p { Line 697  p {
697      The document is non-conforming.</p>      The document is non-conforming.</p>
698    </div>    </div>
699    
700  <div class="section parse-error" id="in-head:head"><h3>Start tag <code>&lt;head&gt;</code>  <div class="section" id="in-body:#eof"><h3>Some element is not closed before the end of
701      file.</h3></div>
702    
703    <div class="section" id="in-button:button"><h3>The <code>button</code> element cannot be
704      nested.</h3></div>
705    
706    <div class="section" id="in-CDATA:#eof"><h3>Element is not closed before the end of
707      file.</h3></div>
708    
709    <div class="section" id="in-form:form"><h3>Start tag <code>&lt;form&gt;</code> is
710      not allowed in a <code>form</code> element.</h3></div>
711    
712    <div class="section" id="in-frameset"><h3>Start tag <code>&lt;<var>{text}</var>&gt;</code> is
713      not allowed in a <code>framset</code> element.</h3></div>
714    
715    <div class="section" id="in-frameset:/"><h3>End tag <code>&lt;/<var>{text}</var>&gt;</code> is
716      not allowed in a <code>frameset</code> element.</h3></div>
717    
718    <div class="section" id="in-frameset:#text"><h3>Non‐white‐space characters are not allowed
719      in a <code>frameset</code> element.</h3></div>
720    
721    <div class="section" id="in-head:head"><h3>Start tag <code>&lt;head&gt;</code>
722    is not allowed in the <code>head</code> element.</h3>    is not allowed in the <code>head</code> element.</h3>
723      <p>There is a start tag <code>&lt;head&gt;</code> in the      <p>There is a start tag <code>&lt;head&gt;</code> in the
724      <code>&lt;head&gt;</code> element.  The document is non-conforming.</p>      <code>&lt;head&gt;</code> element.  The document is non-conforming.</p>
# Line 477  p { Line 728  p {
728      start tag <code>&lt;head&gt;</code> can appear in the input stream.</p>      start tag <code>&lt;head&gt;</code> can appear in the input stream.</p>
729    </div>    </div>
730    
731  <div class="section parse-error" id="in-table"><h3>Tag <code>&lt;<var>$0</var>&gt;</code>  <div class="section" id="in-html:#DOCTYPE"><h3>A <code>DOCTYPE</code> appears after any
732      element or data character has been seen.</h3>
733        <p>A <code>DOCTYPE</code> appears after any element or data character
734        has been seen.  The document is non-conforming.</p>
735        
736        <p>The <code>DOCTYPE</code> must be placed before any
737        tag, reference, or data character.  Only white space characters
738        and comments can be inserted before the <code>DOCTYPE</code>.</p>
739      </div>
740    
741    <div class="section" id="in-nobr:nobr"><h3>The <code>nobr</code> element cannot be
742      nested.</h3></div>
743    
744    <div class="section" id="in-noscript"><h3>The <code><var>{text}</var></code> element is not
745      allowed in a <code>noscript</code> element in the
746      <code>head</code> element.</h3></div>
747    
748    <div class="section" id="in-noscript:/"><h3>An end tag <code>&lt;/<var>{text}</var>&gt;</code>
749      appers before the <code>noscript</code> element is closed.</h3></div>
750    
751    <div class="section" id="in-noscript:#eof"><h3>A <code>noscript</code> element is not closed
752      before the end of file.</h3></div>
753    
754    <div class="section" id="in-noscript:#text"><h3>Non‐white‐space characters are not allowed
755      in a <code>noscript</code> element in the <code>head</code>
756      element.</h3></div>
757    
758    <div class="section" id="in-PCDATA:#eof"><h3>Element is not closed before the end of
759      file.</h3></div>
760    
761    <div class="section" id="in-select"><h3>Start tag <code>&lt;<var>{text}</var>&gt;</code>
762      is not allowed in a <code>select</code> element.</h3></div>
763    
764    <div class="section" id="in-select:/"><h3>End tag <code>&lt;/<var>{text}</var>&gt;</code>
765      is not allowed in a <code>select</code> element.</h3></div>
766    
767    <div class="section" id="in-table"><h3>Start tag <code>&lt;<var>{text}</var>&gt;</code>
768    is not allowed in a <code>table</code> element.</h3>    is not allowed in a <code>table</code> element.</h3>
769      <p>The start or end tag of an element, which      <p>The start or end tag of an element, which
770      cannot be a child of <code>table</code> element, appears      cannot be a child of <code>table</code> element, appears
# Line 491  p { Line 778  p {
778      a table caption.</p>      a table caption.</p>
779    </div>    </div>
780    
781  <div class="section parse-error" id="in-table:#character"><h3>Data character is not allowed in  <div class="section" id="in-table:/"><h3>End tag <code>&lt;/<var>{text}</var>&gt;</code>
782    <code>table</code>.</h3>    is not allowed in a <code>table</code> element.</h3></div>
783      <p>A data character appears in <code>table</code>.  The document  
784      is non-conforming.</p>  <div class="section" id="in-table:#text"><h3>Non‐white‐space character is not allowed within
785      the <code>table</code> element, outside of the caption and cells.</h3>
786        <p>A non‐white‐space character appears in <code>table</code>.
787        The document is non-conforming.</p>
788    
789      <p>In <code>table</code>, only table related elements      <p>In <code>table</code>, only table related elements
790      are allowed; any other element and data character must be contained in      are allowed; any other element and data character must be contained in
# Line 503  p { Line 793  p {
793      a table caption.</p>      a table caption.</p>
794    </div>    </div>
795    
796  <div class="section parse-error" id="missing-start-tag:tr"><h3>Start tag of <code>tr</code>  <div class="section" id="isindex"><h3>The <code>isindex</code> element is
797      obsolete.</h3></div>
798    
799    <div class="section" id="missing-start-tag:tr"><h3>Start tag of <code>tr</code>
800    element is missing.</h3>    element is missing.</h3>
801      <p>Start tag of a <code>tr</code> element, which is <em>not</em>      <p>Start tag of a <code>tr</code> element, which is <em>not</em>
802      optional, is missing.  The document is non-conforming.</p>      optional, is missing.  The document is non-conforming.</p>
# Line 515  p { Line 808  p {
808      these start tags, it must be explicitly specified.</p>      these start tags, it must be explicitly specified.</p>
809    </div>    </div>
810    
811  <div class="section parse-error" id="no-DOCTYPE"><h3>This document does not start with a  <div class="section" id="no-DOCTYPE"><h3>This document does not start with a
812    <code>DOCTYPE</code>.</h3>    <code>DOCTYPE</code>.</h3>
813      <p>The document does not start with a <code>DOCTYPE</code>.      <p>The document does not start with a <code>DOCTYPE</code>.
814      The document is non-conforming.</p>      The document is non-conforming.</p>
# Line 530  p { Line 823  p {
823      allowed in HTML document.</p>      allowed in HTML document.</p>
824    </div>    </div>
825    
826  <div class="section parse-error" id="not-closed"><h3>Element <code><var>$0</var></code> is not  <div class="section" id="not-closed"><h3>Element <code><var>{text}</var></code> is not
827    closed.</h3>    closed.</h3>
828      <p>End tag of an element is not found before, for example,      <p>End tag of an element is not found before, for example,
829      an end tag of another element appears or      an end tag of another element appears or
# Line 559  p { Line 852  p {
852      allowed and they also cause this error.</p>      allowed and they also cause this error.</p>
853    </div>    </div>
854    
855  <div class="section parse-error" id="not-first-start-tag"><h3>This <code>&lt;html&gt;</code> tag is not  <div class="section" id="not-first-start-tag"><h3>This <code>&lt;html&gt;</code> tag is not
856    the first start tag.</h3>    the first start tag.</h3>
857      <p>There is a start tag of the <code>html</code> element      <p>There is a start tag of the <code>html</code> element
858      that it not the first start tag in the input stream.      that it not the first start tag in the input stream.
# Line 573  p { Line 866  p {
866      and comments.</p>      and comments.</p>
867    </div>    </div>
868    
869  <div class="section parse-error" id="not-HTML5"><h3>This document is written in an old version of  <div class="section" id="not-HTML5"><h3>This document is written in an old version of
870    HTML.</h3>    HTML.</h3>
871      <p>The document contains a <code>DOCTYPE</code> declaration      <p>The document contains a <code>DOCTYPE</code> declaration
872      that is different from HTML5 <code>DOCTYPE</code> (i.e.      that is different from HTML5 <code>DOCTYPE</code> (i.e.
# Line 587  p { Line 880  p {
880      HTML document (roughly) as defined in HTML5.</p>      HTML document (roughly) as defined in HTML5.</p>
881    </div>    </div>
882    
883  <div class="section parse-error" id="unmatched-end-tag"><h3>Element <code><var>$0</var></code> is not  <div class="section" id="start-tag-not-allowed"><h3>Start tag <code>&lt;<var>{text}</var>&gt;</code> is
884      not allowed here.</h3></div>
885    
886    <div class="section" id="unmatched-end-tag"><h3>Element <code><var>{text}</var></code> is not
887    opened.</h3>    opened.</h3>
888      <p>An end tag appears though no element with the same name      <p>An end tag appears though no element with the same name
889      has been opened.  The document is non-conforming.</p>      has been opened.  The document is non-conforming.</p>
# Line 609  p { Line 905  p {
905      </dl>      </dl>
906    </div>    </div>
907    
908    <div class="section" id="XSLT-compat"><h3>The <code>DOCTYPE</code> legacy string is
909      used.</h3>
910        <p>The <code>DOCTYPE</code> with the <code>DOCTYPE</code> legacy
911        string, i.e.
912        <code class="html bad example">&lt;!DOCTYPE HTML PUBLIC "XSLT-compat"&gt;</code>
913        is used.</p>
914    
915        <p>The <code>DOCTYPE</code> legacy string should not be used for documents
916        generated from XSLT transformation process.  It is allowed only to enable
917        to use XSLT style sheets with the HTML output mode, which does not
918        support generation of the <code>DOCTYPE</code> with no <code>PUBLIC</code>
919        identifier.  For other purposes, the <code>DOCTYPE</code> legacy
920        string, i.e. <code class="html bad example">PUBLIC "XSLT-compat"</code>,
921        is useless and should not be used.</p>
922      </div>
923    
924  </section>  </section>
925    
926  <section id="element-content-model-errors">  <section id="element-content-model-errors">
927  <h2>Element Content Model Errors</h2>  <h2>Element Content Model Errors</h2>
928    
929  <div class="section content-model-error" id="character-not-allowed"><h3>Data character is not allowed in this  <div class="section" id="basehref-after-URL-attribute"><h3>The <code>base</code> element with the
930      <code>href</code> attribute specified cannot be placed after
931      any attribute with a URL.</h3></div>
932    
933    <div class="section" id="basetarget-after-hyperlink"><h3>The <code>base</code> element with the
934      <code>target</code> attribute specified cannot be placed after
935      any element that defines a hyperlink.</h3></div>
936    
937    <div class="section" id="character-not-allowed"><h3>Data character is not allowed in this
938    context.</h3>    context.</h3>
939      <p>A data character appears where it is not allowed in this      <p>A data character appears where it is not allowed in this
940      context.  The document is non-conforming.</p>      context.  The document is non-conforming.</p>
# Line 637  p { Line 957  p {
957      </p>      </p>
958    </div>    </div>
959    
960  <div class="section content-model-error" id="child-element-missing"><h3>There must be a <code><var>$0</var></code>  <div class="section" id="character-not-allowed:empty"><h3>Non‐white‐space characters are not allowed in
961    element as a child of this element.</h3>    an empty element.</h3></div>
962    
963    <div class="section" id="character-not-allowed:atom|PersonConstruct"><h3>Non‐white‐space characters are not allowed in
964      Person construct.</h3></div>
965    
966    <div class="section" id="character-not-allowed:atom|TextConstruct"><h3>Non‐white‐space characters are not allowed in
967      Text construct.</h3></div>
968    
969    <div class="section" id="child-element-missing"><h3>There must be an element
970      <code><var>{text}</var></code> as a child of this element.</h3>
971      <p>The content model of the element is so defined that it      <p>The content model of the element is so defined that it
972      must contain a <code><var>$0</var></code> child element.      must contain a <code><var>$0</var></code> child element.
973      The document is non-conforming.</p>      The document is non-conforming.</p>
# Line 655  p { Line 984  p {
984      </dl>      </dl>
985    </div>    </div>
986    
987  <div class="section content-model-error" id="child-element-missing:td|th"><h3>There must be a <code>td</code>  <div class="section" id="child-element-missing:td|th"><h3>There must be a <code>td</code>
988    or <code>th</code> element as a child of this element.</h3>    or <code>th</code> element as a child of this element.</h3>
989      <p>The <code>tr</code> element must contain at least one      <p>The <code>tr</code> element must contain at least one
990      <code>td</code> or <code>th</code> child element.  The document      <code>td</code> or <code>th</code> child element.  The document
991      is non-conforming.</p>      is non-conforming.</p>
992    </div>    </div>
993    
994  <div class="section content-model-error" id="element-not-allowed"><h3>This element is not allowed in this  <div class="section" id="child-element-missing:atom"><h3>There must be an element
995      <code><var>{text}</var></code> in the Atom namespace as a child of this
996      element.</h3></div>
997    
998    <div class="section" id="child-element-missing:atom:link:alternate"><h3>There must be an Atom <code>link</code> element
999      whose <code>rel</code> attribute is set to <code>alternate</code> as a
1000      child of this element.</h3></div>
1001    
1002    <div class="section" id="child-element-missing:atom:link:self"><h3>There should be an Atom <code>link</code> element
1003      whose <code>rel</code> attribute is set to <code>self</code> as a
1004      child of this element.</h3></div>
1005    
1006    <div class="section" id="element-missing:hn"><h3>There must be at least one
1007      <code>h<var>n</var></code> element descendant.</h3></div>
1008    
1009    <div class="section" id="element-not-allowed"><h3>This element is not allowed in this
1010    context.</h3>    context.</h3>
1011      <p>An element appears where it is not allowed.  The document      <p>An element appears where it is not allowed.  The document
1012      is non-conforming.</p>      is non-conforming.</p>
# Line 727  p { Line 1071  p {
1071      </p>      </p>
1072    </div>    </div>
1073    
1074  <div class="section content-model-error" id="element-not-allowed:root"><h3>This element is not allowed as a root  <div class="section" id="element-not-allowed:area"><h3>An <code>area</code> element cannot be used
1075    element.</h3>    outside of a <code>map</code> element.</h3></div>
1076    
1077    <div class="section" id="element-not-allowed:base"><h3>There is another <code>base</code>
1078      element.</h3></div>
1079    
1080    <div class="section" id="element-not-allowed:datatemplate"><h3>In a <code>datatemplate</code> element, only
1081      <code>rule</code> elements are allowed.</h3></div>
1082    
1083    <div class="section" id="element-not-allowed:details-legend"><h3>In a <code>details</code> element, only at the
1084      beginning of the element a <code>lengend</code> element
1085      may be used.</h3></div>
1086    
1087    <div class="section" id="element-not-allowed:empty"><h3>Elements are not allowed in an empty
1088      element.</h3></div>
1089    
1090    <div class="section" id="element-not-allowed:figure-legend"><h3>In a <code>figure</code> element, only at the
1091      beginning or only at the end of the element a <code>lengend</code> element
1092      may be used.</h3></div>
1093    
1094    <div class="section" id="element-not-allowed:flow"><h3>This element is not allowed where flow
1095      content is expected.</h3></div>
1096    
1097    <div class="section" id="element-not-allowed:flow-style"><h3>A <code>style</code> element without
1098      <code>scoped</code> attribute is not allowed in this context.</h3></div>
1099    
1100    <div class="section" id="element-not-allowed:head-noscript"><h3>This element is not allowed in a
1101      <code>noscript</code> element in the <code>head</code> element.</h3></div>
1102    
1103    <div class="section" id="element-not-allowed:head-style"><h3>A <code>style</code> element with
1104      <code>scoped</code> attribute is not allowed in the <code>head</code>
1105      element.</h3></div>
1106    
1107    <div class="section" id="element-not-allowed:head-title"><h3>There is another <code>title</code>
1108      element.</h3></div>
1109    
1110    <div class="section" id="element-not-allowed:minus"><h3>This element is not allowed in this
1111      context.</h3></div>
1112    
1113    <div class="section" id="element-not-allowed:meta-charset"><h3>The character encoding declaration is not the
1114      first child element in the <code>head</code> element.</h3>
1115        <p>The character encoding declaration
1116        (<code class="html example">&lt;meta charset="<var>...</var>"&gt;</code> or
1117        <code class="html example">&lt;meta http-equiv=Content-Type content="text/html; charset=<var>...</var>"&gt;</code>
1118        must be the first child element in the <code>head</code> element.</p>
1119    
1120        <p>The character encoding declaration have to occur near the beginning
1121        of the document to ensure that Web browsers can be determine the
1122        character encoding of the document.</p>
1123    
1124        <p>The <code>title</code> element and other metadata elements must
1125        appear after any character encoding declaration is processed.</p>
1126      </div>
1127    
1128    <div class="section" id="element-not-allowed:metadata"><h3>This element is not allowed where metadata
1129      content is expected.</h3></div>
1130    
1131    <div class="section" id="element-not-allowed:phrasing"><h3>This element is not allowed where phrasing
1132      content is expected.</h3></div>
1133    
1134    <div class="section" id="element-not-allowed:root"><h3>This element is not allowed as the root
1135      element of a document.</h3>
1136      <p>An element that is not allowed as the root element      <p>An element that is not allowed as the root element
1137      is used as the root element of the document.  The document is      is used as the root element of the document.  The document is
1138      non-conforming, as far as the conformance checker can tell.</p>      non-conforming, as far as the conformance checker can tell.</p>
# Line 738  p { Line 1142  p {
1142          <dd><p>In <abbr>XHTML</abbr> document, the root <code>html</code>          <dd><p>In <abbr>XHTML</abbr> document, the root <code>html</code>
1143          element must have an <code>xmlns</code> attribute as:          element must have an <code>xmlns</code> attribute as:
1144            <pre class="xml example">            <pre class="xml example">
1145  <code>&lt;html xmlns=&quot;http://www.w3.org/1999/xhtml&quot;&gt;</code></pre></p></dd>  <code>&lt;html xmlns="http://www.w3.org/1999/xhtml"&gt;</code></pre></p></dd>
1146      <dt><code>rss</code> element</dt>      <dt><code>rss</code> element</dt>
1147          <dd><p>The document is written in some version of RSS.</p>          <dd><p>The document is written in some version of RSS.</p>
1148          <p>The conformance checker does not support any version          <p>The conformance checker does not support any version
# Line 748  p { Line 1152  p {
1152          in the <code>http://www.w3.org/2005/Atom</code>          in the <code>http://www.w3.org/2005/Atom</code>
1153          namespace as:          namespace as:
1154            <pre class="xml example">            <pre class="xml example">
1155  <code>&lt;feed xmlns=&quot;http://www.w3.org/2005/Atom&quot;&gt;</code></pre>  <code>&lt;feed xmlns="http://www.w3.org/2005/Atom"&gt;</code></pre>
1156          </p>          </p>
1157          <p>The conformance checker does not support Atom 0.3.          <p>The conformance checker does not support Atom 0.3.
1158          Use Atom 1.0 for feed documents.</p></dd>          Use Atom 1.0 for feed documents.</p></dd>
1159      </dl>      </dl>
1160    </div>    </div>
1161    
1162  <div class="section content-model-error" id="ps-element-missing"><h3>There is no <code><var>$0</var></code>  <div class="section" id="element-not-allowed:root:xml"><h3>This element is not allowed as the root element
1163      of an XML document.</h3></div>
1164    
1165    <div class="section" id="element-not-allowed:ruby-base"><h3>This element is not allowed in the <code>ruby</code>
1166      element.</h3></div>
1167    
1168    <div class="section" id="element-not-allowed:text"><h3>This element is not allowed in this
1169      context.</h3></div>
1170    
1171    <div class="section" id="element-not-allowed:atom|content"><h3>This element is not allowed in an Atom
1172      <code>content</code> element.</h3></div>
1173    
1174    <div class="section" id="element-not-allowed:atom|PersonConstruct"><h3>This element is not allowed in Person
1175      construct.</h3></div>
1176    
1177    <div class="section" id="element-not-allowed:atom|TextConstruct"><h3>This element is not allowed in Text
1178      construct.</h3></div>
1179    
1180    <div class="section" id="element-not-defined"><h3>This element is not defined.</h3>
1181        <p>The element is not one of elements allowed
1182        in the latest version of relevant specifications.</p>
1183    
1184        <p>The element cannot be used.</p>
1185    
1186        <dl class="switch">
1187        <dt><code>event-source</code> element</dt>
1188            <dd>The element was renamed as <em><code>eventsource</code>
1189            element</em> (no hyphen).</dd>
1190        <dt><code>m</code> element</dt>
1191            <dd>The element was renamed as <em><code>mark</code>
1192            element</em>.</dd>
1193        </dl>
1194      </div>
1195    
1196    <div class="section" id="no-significant-content"><h3>No significant content is contained
1197      in this element.</h3></div>
1198    
1199    <div class="section" id="no-significant-content-before"><h3>There is no significant content
1200      before this element.</h3></div>
1201    
1202    <div class="section" id="no-significant-content-at-the-end"><h3>No significant content is contained
1203      at the end of this element.</h3></div>
1204    
1205    <div class="section" id="ps-element-missing"><h3>There is no <code><var>{text}</var></code>
1206    element before this element.</h3>    element before this element.</h3>
1207      <p>There must be an element before another element, but there      <p>There must be an element before another element, but there
1208      is not.  The document is non-conforming.</p>      is not.  The document is non-conforming.</p>
# Line 764  p { Line 1211  p {
1211      before any <code>dd</code> element.</p>      before any <code>dd</code> element.</p>
1212    </div>    </div>
1213    
1214    <div class="section" id="rp:syntax-error"><h3>The content of a <code>rp</code> element must
1215      be a parenthesis.</h3></div>
1216    
1217  </section>  </section>
1218    
1219  <section id="attribute-errors">  <section id="attribute-errors">
1220  <h2>Attribute Errors</h2>  <h2>Attribute Errors</h2>
1221    
1222  <div class="section attribute-error" id="attribute-missing"><h3>Required attribute <code><var>$0</var></code>  <div class="section" id="attribute-missing"><h3>Required attribute <code><var>{text}</var></code>
1223    is not specified.</h3>    is not specified.</h3>
1224      <p>A required attribute is not specified.  The document      <p>A required attribute is not specified.  The document
1225      is non-conforming.</p>      is non-conforming.</p>
# Line 789  p { Line 1239  p {
1239      </dl>      </dl>
1240    </div>    </div>
1241    
1242  <div class="section attribute-error" id="attribute-not-allowed"><h3>Attribute  <div class="section" id="attribute-missing:data|type"><h3>For an <code>object</code> at least one of
1243      <code>data</code> and <code>type</code> attributes must be
1244      specified.</h3></div>
1245    
1246    <div class="section" id="attribute-missing:href|target"><h3>For a <code>base</code> element, at least one of
1247      <code>href</code> and <code>target</code> attributes must be
1248      specified.</h3></div>
1249    
1250    <div class="section" id="attribute-missing:name|http-equiv"><h3>For a <code>meta</code> element with the
1251      <code>content</code> attribute specified, exactly one of
1252      <code>name</code> and <code>http-equiv</code> attributes must be
1253      specified.</h3></div>
1254    
1255    <div class="section" id="attribute-missing:name|http-equiv|charset"><h3>For a <code>meta</code> element, exactly one of
1256      <code>name</code>, <code>http-equiv</code>, and <code>charset</code>
1257      attributes must be specified.</h3></div>
1258    
1259    <div class="section" id="attribute-not-allowed"><h3>Attribute
1260    <code><var>{local-name}</var></code> is not allowed for    <code><var>{local-name}</var></code> is not allowed for
1261    <code><var>{element-local-name}</var></code> element.</h3>    <code><var>{element-local-name}</var></code> element.</h3>
1262      <p>An attribute is specified where it is not allowed.      <p>An attribute is specified where it is not allowed.
# Line 803  p { Line 1270  p {
1270      </dl>      </dl>
1271    </div>    </div>
1272    
1273  <div class="section attribute-error" id="in-HTML:xml:lang"><h3>The <code>xml:lang</code> attribute is not  <div class="section" id="attribute-not-allowed:ismap"><h3>The <code>ismap</code> attribute may only be
1274    allowed in HTML document.</h3>    used for the image contained in an <code>a</code> element.</h3></div>
1275      <p>The <code>xml:lang</code> attribute is not allowed in  
1276      HTML document.  The document is non-conforming.</p>  <div class="section" id="attribute-not-defined"><h3>This attribute is not defined.</h3>
1277        <p>The attribute is not one of attributes allowed for the element
1278        in the latest version of relevant specifications.</p>
1279    
1280        <p>The attribute cannot be used.</p>
1281    
1282        <dl class="switch">
1283        <dt><code>align</code> attribute (various HTML elements)</dt>
1284        <dt><code>border</code> attribute (various HTML elements)</dt>
1285          <dd>These attributes are no longer part of HTML.  You can use CSS
1286          properties to control the presentation of the element.</dd>
1287        <dt><code>autosubmit</code> attribute (<code>menu</code> element)</dt>
1288          <dd>The attribute was part of HTML5 draft but then dropped.
1289          Similar functionality can be implemented by scripts.</dd>
1290        <dt><code>language</code> attribute (<code>script</code> element)</dt>
1291          <dd>The attribute is no longer the standard way to specify the
1292          scripting language.  If you are using JavaScript, then no explicit
1293          specification of the scripting language is necessary, so you can
1294          write the element like:
1295            <p><code class="html example code">&lt;script&gt;<br><!--
1296            --> /* JavaScript code */<br><!--
1297            -->&lt;/script&gt;</code></p>
1298          If you are using different scripting language from JavaScript, or
1299          you want to declare the scripting language explicitly, you should
1300          use the <code>type</code> attribute, as follows:
1301            <dl class="switch">
1302            <dt>JavaScript</dt>
1303              <dd>Use
1304              <code class="html example">&lt;script type="text/javascript"&gt;</code>.</dd>
1305            <dt>VBScript</dt>
1306              <dd>Use
1307              <code class="html example">&lt;script type="text/vbscript"&gt;</code>.</dd>
1308            </dl>
1309          </dd>
1310        </dl>
1311      </div>
1312    
1313      <p>Use of the <code>xml:lang</code> attribute is conforming  <div class="section" id="in-HTML:xml:lang"><h3>The <code>xml:lang</code> attribute in HTML
1314      <em>only</em> in XML documents.</p>    document is ignored.</h3>
1315        <p>The <code>xml:lang</code> attribute does not have an effect in
1316        HTML document.</p>
1317    
1318        <p>The <code>xml:lang</code> attribute is only applicable to XML
1319        documents.  In HTML document, it is only allowed to ease migration
1320        from XML.</p>
1321    
1322      <p>To specify natural language information in HTML document,      <p>To specify natural language information in HTML document,
1323      use <code>lang</code> attribute instead.</p>      use <code>lang</code> attribute instead.</p>
# Line 824  p { Line 1332  p {
1332           from an HTML document? -->           from an HTML document? -->
1333    </div>    </div>
1334    
1335  <div class="section attribute-error" id="in-XML:charset"><h3>The <code>charset</code> attribute is not  <div class="section" id="in-XML:charset"><h3>The <code>charset</code> attribute is not
1336    allowed in XML document.</h3>    allowed in XML document.</h3>
1337      <p>The <code>charset</code> attribute of a      <p>The <code>charset</code> attribute of a
1338      <code>meta</code> element is not allowed in XML document.      <code>meta</code> element is not allowed in XML document.
# Line 833  p { Line 1341  p {
1341      <p>To specify the character encoding used for serialization,      <p>To specify the character encoding used for serialization,
1342      if necessary, use XML declaration instead:      if necessary, use XML declaration instead:
1343        <pre class="xml example">        <pre class="xml example">
1344  <code>&lt;?xml version=&quot;1.0&quot; encoding=&quot;<var>encoding-name</var>&quot;?&gt;</code></pre>  <code>&lt;?xml version="1.0" encoding="<var>encoding-name</var>"?&gt;</code></pre>
1345      </p>      </p>
1346    </div>    </div>
1347    
1348  <div class="section attribute-error" id="in-XML:lang"><h3>The <code>lang</code> attribute is not  <div class="section" id="in-XML:noscript"><h3>A <code>noscript</code> element cannot be
1349    allowed in XML document.</h3>    used in XML document.</h3></div>
     <p>The HTML <code>lang</code> attribute is not allowed in  
     XML document.  The document is non-conforming.</p>  
   
     <p>The <code>lang</code> attribute in <code>null</code>  
     namespace for HTML elements is conforming <em>only</em> in  
     HTML documents.</p>  
1350    
1351      <p>To specify natural language information in XML document,  <div class="section" id="in-XML:xml:lang"><h3>The <code>xml:lang</code> attribute in no namespace
1352      use <code>xml:lang</code> attribute instead.</p>    is only allowed in HTML document.</h3></div>
   </div>  
1353    
1354  <div class="section attribute-error" id="in-XML:xmlns"><h3>The <code>xmlns</code> attribute  <div class="section" id="in-XML:xmlns"><h3>The <code>xmlns</code> attribute
1355    in the <code>null</code> namespace is not allowed in    in the <code>null</code> namespace is not allowed in
1356    XHTML document.  The document is non-conforming.</h3>    XHTML document.  The document is non-conforming.</h3>
1357      <p>The <code>xmlns</code> attribute in the <code>null</code>      <p>The <code>xmlns</code> attribute in the <code>null</code>
# Line 860  p { Line 1361  p {
1361      static documents.</p>      static documents.</p>
1362    </div>    </div>
1363    
1364    <div class="section" id="xml:lang-not-allowed"><h3>The <code>xml:lang</code> attribute is only allowed
1365      when the <code>lang</code> attribute is specified.</h3></div>
1366    
1367  </section>  </section>
1368    
1369  <section id="attribute-value-errors">  <section id="attribute-value-errors">
1370  <h2>Attribute Value Errors</h2>  <h2>Attribute Value Errors</h2>
1371    
1372  <div class="section attribute-value-warning warning" id="w:charset:not-registered"><h3>Character encoding name <code><var>$0</var></code>  <div class="section" id="boolean:invalid"><h3>Attribute value <code><var>{@}</var></code>
1373    is not registered.</h3>    is not allowed.  It must be an empty string or a string
1374      <code><var>{local-name}</var></code>.</h3></div>
1375    
1376    <div class="section" id="char:syntax-error"><h3>The attribute value must be exactly one
1377      character.</h3></div>
1378    
1379    <div class="section" id="charref-in-charset"><h3>A character reference cannot be used to
1380      represent a character encoding name.</h3></div>
1381    
1382    <div class="section" id="charset:not-preferred"><h3>Character encoding name
1383      <code><var>{value}</var></code> is not the preferred name of that
1384      character encoding.</h3></div>
1385    
1386    <div class="section" id="charset:not-registered"><h3>Character encoding name
1387      <code><var>{value}</var></code> is not a registered name.</h3>
1388      <p>The specified character encoding name is not registered to      <p>The specified character encoding name is not registered to
1389      <abbr>IANA</abbr>.  Use of registered character encoding name      <abbr>IANA</abbr>.  Use of registered character encoding name
1390      is a good practice to facilitate interoperability.</p>      is a good practice to facilitate interoperability.</p>
# Line 907  p { Line 1425  p {
1425      name database of the conformance checker is not complete yet.</p>      name database of the conformance checker is not complete yet.</p>
1426    </div>    </div>
1427    
1428  <div class="section attribute-value-warning warning" id="w:charset:private"><h3><code><var>$0</var></code> is a private  <div class="section" id="charset:private"><h3>Character encoding name
1429    character encoding name.</h3>    <code><var>{value}</var></code> is a private name.</h3>
1430      <p>The specified character encoding name is a private name and      <p>The specified character encoding name is a private name and
1431      not registered to <abbr>IANA</abbr>.  Use of registered character      not registered to <abbr>IANA</abbr>.  Use of registered character
1432      encoding name is a good practice to facilitate interoperability.</p>      encoding name is a good practice to facilitate interoperability.</p>
# Line 925  p { Line 1443  p {
1443      </dl>      </dl>
1444    </div>    </div>
1445    
1446  <div class="section attribute-value-error" id="m:charset:syntax-error"><h3>The specified value is syntactically not a  <div class="section" id="charset:syntax-error"><h3>The specified value <code><var>{value}</var></code>
1447    character encoding name.</h3>    is syntactically not a character encoding name.</h3>
1448      <p>The attribute value must be a character encoding name.  However,      <p>The attribute value must be a character encoding name.  However,
1449      the specified value is not a character encoding name syntactically.      the specified value is not a character encoding name syntactically.
1450      The document is non‐conforming.</p>      The document is non‐conforming.</p>
# Line 934  p { Line 1452  p {
1452      printable characters, up to 40 characters.</p>      printable characters, up to 40 characters.</p>
1453    </div>    </div>
1454    
1455  <div class="section attribute-value-error" id="enumerated:invalid"><h3>This attribute only allow a limited set of  <div class="section" id="color:syntax-error"><h3>The specified value is not a color
1456      name or hexadecimal color number.</h3></div>
1457    
1458    <div class="section" id="coords:number-not-3"><h3>The <code>coords</code> attribute have to
1459      contain three (3) numbers (specified:
1460      <code><var>{text}</var></code>).</h3></div>
1461    
1462    <div class="section" id="coords:number-not-4"><h3>The <code>coords</code> attribute have to
1463      contain four (4) numbers (specified:
1464      <code><var>{text}</var></code>).</h3></div>
1465    
1466    <div class="section" id="coords:number-lt-6"><h3>The <code>coords</code> attribute have to
1467      contain more than or equal to six (6) numbers (specified:
1468      <code><var>{text}</var></code>).</h3></div>
1469    
1470    <div class="section" id="coords:number-not-even"><h3>The <code>coords</code> attribute have to
1471      contain even number of numbers (specified:
1472      <code><var>{text}</var></code>).</h3></div>
1473    
1474    <div class="section" id="coords:out-of-range"><h3>The specified value <code><var>{value}</var></code>
1475      is out of range.</h3></div>
1476    
1477    <div class="section" id="coords:syntax-error"><h3>The specified value is not valid.</h3></div>
1478    
1479    <div class="section" id="datetime:bad-year"><h3>Year number is out of range.</h3></div>
1480    
1481    <div class="section" id="datetime:bad-month"><h3>Month number is out of range.</h3></div>
1482    
1483    <div class="section" id="datetime:bad-day"><h3>Day number is out of range.</h3></div>
1484    
1485    <div class="section" id="datetime:bad-hour"><h3>Hour number is out of range.</h3></div>
1486    
1487    <div class="section" id="datetime:bad-minute"><h3>Minute number is out of range.</h3></div>
1488    
1489    <div class="section" id="datetime:bad-second"><h3>Second number is out of range.</h3></div>
1490    
1491    <div class="section" id="datetime:bad-timezone-hour"><h3>Hour number of the timezone component is out of
1492      range.</h3></div>
1493    
1494    <div class="section" id="datetime:bad-timezone-minute"><h3>Minute number of the timezone component is out of
1495      range.</h3></div>
1496    
1497    <div class="section" id="datetime:syntax-error"><h3>The attribute value is not a datetime.</h3></div>
1498    
1499    <div class="section" id="dateortime:syntax-error"><h3>The value is not a date or time.</h3></div>
1500    
1501    <div class="section" id="enumerated:invalid"><h3>This attribute only allow a limited set of
1502    values and the specified value <code><var>{@}</var></code> is not one    values and the specified value <code><var>{@}</var></code> is not one
1503    of them.</h3>    of them.</h3>
1504      <p>For this attribute only several values are allowed and the      <p>For this attribute only several values are allowed and the
# Line 948  p { Line 1512  p {
1512          <p>Value <code>Content-Type</code> is obsolete; for charset          <p>Value <code>Content-Type</code> is obsolete; for charset
1513          declaration, the <code>charset</code> attribute can be used as:          declaration, the <code>charset</code> attribute can be used as:
1514          <pre class="html example">          <pre class="html example">
1515  <code>&lt;meta charset=&quot;<var>charset-name</var>&quot;&gt;</code></pre>  <code>&lt;meta charset="<var>charset-name</var>"&gt;</code></pre>
1516          ... where <var>charset-name</var> is a name of the character encoding          ... where <var>charset-name</var> is a name of the character encoding
1517          of the document, such as <code>utf-8</code>.</p>          of the document, such as <code>utf-8</code>.</p>
1518          <p>Values <code>Content-Style-Type</code> and          <p>Values <code>Content-Style-Type</code> and
# Line 962  p { Line 1526  p {
1526      </dl>      </dl>
1527    </div>    </div>
1528    
1529  <div class="section attribute-value-error" id="enumerated:invalid:http-equiv:content-type"><h3>Character encoding declaration syntax  <div class="section" id="enumerated:invalid:http-equiv:content-type"><h3>Character encoding declaration syntax
1530    <code class="html bad example">&lt;meta http-equiv=&quot;Content-Type&quot; content=&quot;text/html; charset=<var>charset-name</var>&quot;&gt;</code>    <code class="html bad example">&lt;meta http-equiv="Content-Type" content="text/html; charset=<var>charset-name</var>"&gt;</code>
1531    is obsolete.</h3>    is obsolete.</h3>
1532      <p>Old long character encoding declaration syntax      <p>Old long character encoding declaration syntax
1533      <code class="html bad example">&lt;meta http-equiv=&quot;Content-Type&quot; content=&quot;text/html; charset=<var>charset-name</var>&quot;&gt;</code>      <code class="html bad example">&lt;meta http-equiv="Content-Type" content="text/html; charset=<var>charset-name</var>"&gt;</code>
1534      is in use.  The document is non‐conforming.</p>      is in use.  The document is non‐conforming.</p>
1535    
1536      <p>The new character encoding declaration syntax is:      <p>The new character encoding declaration syntax is:
1537        <pre class="html example">        <pre class="html example">
1538  <code>&lt;meta charset=&quot;<var>charset-name</var>&quot;&gt;</code></pre>  <code>&lt;meta charset="<var>charset-name</var>"&gt;</code></pre>
1539      </p>      </p>
1540    </div>    </div>
1541    
1542  <div class="section attribute-value-error" id="duplicate-ID"><h3>This identifier has already been  <div class="section" id="enumerated:non-conforming"><h3>Attribute value <code><var>{@}</var></code>
1543      is not allowed.</h3></div>
1544    
1545    <div class="section" id="duplicate-http-equiv"><h3>There is another pragma
1546      <code><var>{value}</var></code>.</h3></div>
1547    
1548    <div class="section" id="duplicate-ID"><h3>This identifier has already been
1549    assigned to another element.</h3></div>    assigned to another element.</h3></div>
1550    
1551  <div class="section attribute-value-error" id="link-type:bad-context"><h3>The link type <code><var>$0</var></code>  <div class="section" id="duplicate-token"><h3>The token <code><var>{value}</var></code>
1552      appears in the attribute value twice.</h3></div>
1553    
1554    <div class="section" id="empty-attribute-value"><h3>The attribute value is empty.</h3></div>
1555    
1556    <div class="section" id="empty-style-sheet-title"><h3>The value of the <code>title</code> attribute
1557      is empty.</h3>
1558        <p>The <code>title</code> attribute value of the <code>link</code>
1559        element that defines an alternate style sheet is an empty value.</p>
1560    
1561        <p>A <code>link</code> element whose <code>rel</code> attribute
1562        is <code>alternate stylesheet</code> defines an alternate style sheet.
1563        An alternate style sheet must be associated with a name using the
1564        <code>title</code> attribute.  The name cannot be empty.</p>
1565      </div>
1566    
1567    <div class="section" id="float:out-of-range"><h3>The specified value is out of range.</h3></div>
1568    
1569    <div class="section" id="float:syntax-error"><h3>The attribute value is not a real
1570      number.</h3></div>
1571    
1572    <div class="section" id="fragment-points-itself"><h3>A fragment identifier references the element
1573      itself.</h3></div>
1574    
1575    <div class="section" id="fragment-points-nothing"><h3>A fragment identifier references no
1576      node.</h3></div>
1577    
1578    <div class="section" id="hashref:syntax-error"><h3>A hash−name reference must start with a
1579      <code>#</code> character.</h3></div>
1580    
1581    <div class="section" id="id-ne-name"><h3>The <code>id</code> attribute value is
1582      different from the <code>name</code> attribute value.</h3></div>
1583    
1584    <div class="section" id="integer:syntax-error"><h3>The attribute value is not an integer.</h3></div>
1585    
1586    <div class="section" id="link-type:bad-context"><h3>The link type <code><var>{value}</var></code>
1587    cannot be specified for this element.</h3>    cannot be specified for this element.</h3>
1588      <p>The specified link type cannot be used for the element.      <p>The specified link type cannot be used for the element.
1589      The document is non-conforming.</p>      The document is non-conforming.</p>
# Line 991  p { Line 1596  p {
1596      while it cannot be used with <code>link</code> element.</p>      while it cannot be used with <code>link</code> element.</p>
1597    </div>    </div>
1598    
1599  <div class="section attribute-value-error" id="link-type:non-conforming"><h3>The link type <code><var>$0</var></code>  <div class="section" id="invalid-attribute-value"><h3>Attribute value <code><var>{@}</var></code>
1600      is not an allowed value.</h3></div>
1601    
1602    <div class="section" id="length:syntax-error"><h3>The attribute value is not a length
1603      value.</h3></div>
1604    
1605    <div class="section" id="link-type:non-conforming"><h3>The link type <code><var>{value}</var></code>
1606    is non-conforming.</h3>    is non-conforming.</h3>
1607      <p>The specified link type is non-conforming, and therefore      <p>The specified link type is non-conforming, and therefore
1608      the document is non-conforming.</p>      the document is non-conforming.</p>
# Line 1012  p { Line 1623  p {
1623      </dl>      </dl>
1624    </div>    </div>
1625    
1626  <div class="section attribute-value-error" id="m:mismatched-charset-name"><h3>Character encoding name <code><var>$1</var></code>  <div class="section" id="meta-content-type-syntax-error"><h3>The specified value is not a valid as a long
1627    is different from document character encoding    character encoding declaration.</h3></div>
1628    <code><var>$0</var></code>.</h3>  
1629    <div class="section" id="mismatched-charset-name"><h3>The specified character encoding name
1630      <code><var>{value}</var></code> is different from the actual document
1631      character encoding <code><var>{text}</var></code>.</h3>
1632      <p>The specified character encoding name is different from      <p>The specified character encoding name is different from
1633      the character encoding of the document.  The document      the character encoding of the document.  The document
1634      is non‐conforming.</p>      is non‐conforming.</p>
1635    </div>    </div>
1636    
1637  <div class="section attribute-value-error" id="reserved-browsing-context-name"><h3>Browsing context name  <div class="section" id="mismatched-charset-name-not-checked"><h3>Whether the specified character encoding name
1638      <code><var>{value}</var></code> matches to the actual character encoding
1639      name cannot be checked since the input is not a byte stream.</h3></div>
1640    
1641    <div class="section" id="mode:syntax-error"><h3>The attribute value is not a valid mode
1642      name.</h3></div>
1643    
1644    <div class="section" id="nninteger:out-of-range"><h3>The specified value is out of range.</h3></div>
1645    
1646    <div class="section" id="nninteger:syntax-error"><h3>The attribute value is not a non‐negative
1647      integer.</h3></div>
1648    
1649    <div class="section" id="no-referenced-map"><h3>The <code>usemap</code> attribute references
1650      no image map.</h3></div>
1651    
1652    <div class="section" id="no-referenced-menu"><h3>The <code>contextmenu</code> attribute references
1653      no menu.</h3></div>
1654    
1655    <div class="section" id="no-referenced-header-cell"><h3>There is no table header cell whose <code>id</code>
1656      is <code><var>{value}</var></code> in the same table.</h3></div>
1657    
1658    <div class="section" id="refresh:syntax-error"><h3>the specified value is not a valid as part
1659      of a <code>Refresh</code> pragma.</h3></div>
1660    
1661    <div class="section" id="repeat:syntax-error"><h3>The attribute value is not an integer or
1662      a string <code>template</code>.</h3></div>
1663    
1664    <div class="section" id="reserved-browsing-context-name"><h3>Browsing context name
1665    <code><var>{@}</var></code> is reserved.</h3>    <code><var>{@}</var></code> is reserved.</h3>
1666      <p>The specified browsing context name is reserved.      <p>The specified browsing context name is reserved.
1667      The document is non-conforming.</p>      The document is non-conforming.</p>
# Line 1036  p { Line 1677  p {
1677      However, they are <em>not</em> conforming attribute values.</p>      However, they are <em>not</em> conforming attribute values.</p>
1678    </div>    </div>
1679    
1680  </section>  <div class="section" id="Reserved-Prefixes-and-Namespace-Names:Name"><h3>Namespace name <code><var>{text}</var></code>
1681      is reserved and cannot be used for an arbitrary prefix.</h3></div>
1682    
1683  <section id="attribute-value-warnings">  <div class="section" id="Reserved-Prefixes-and-Namespace-Names:Prefix"><h3>Namespace prefix <code><var>{text}</var></code>
1684  <h2>Attribute Value Warnings</h2>    is reserved and cannot be used for an arbitrary namespace name.</h3></div>
1685    
1686  <div class="section attribute-value-warning should" id="s:link-type:proposed"><h3>Link type <code><var>$0</var></code>  <div class="section" id="link-type:proposed"><h3>Link type <code><var>{value}</var></code>
1687    is proposed but not accepted yet; it <em>should not</em> be    is proposed but not accepted yet; it <em>should not</em> be
1688    used until it has been accepted.</h3>    used until it has been accepted.</h3>
1689      <p>The link type is in the <i>proposed</i> status; it      <p>The link type is in the <i>proposed</i> status; it
# Line 1055  p { Line 1697  p {
1697      for the latest information.</p>      for the latest information.</p>
1698    </div>    </div>
1699    
1700    <div class="section" id="sizes:syntax-error"><h3>The specified value <code><var>{value}</var></code>
1701      is not a valid value.</h3></div>
1702    
1703    <div class="section" id="space-in-ID"><h3>White space characters are not allowed
1704      in the <code>id</code> attribute.</h3></div>
1705    
1706    <div class="section" id="template:not-template"><h3>The node referenced by the <code>template</code>
1707      attribute is not a template.</h3></div>
1708    
1709    <div class="section" id="window-name:empty"><h3>Browsing context name must not be empty.</h3></div>
1710    
1711    <div class="section" id="window-name:reserved"><h3>Browsing context name
1712      <code><var>{value}</var></code> is reserved.</h3></div>
1713    
1714    <div class="section" id="word-not-allowed"><h3>The word <code><var>{value}</var></code> is not
1715      allowed in this attribute.</h3></div>
1716    
1717    <div class="section" id="XML-1.0-NCName:syntax-error"><h3>The specified value is not a legal XML Namespaces
1718      1.0 <code>NCName</code>.</h3></div>
1719    
1720    <div class="section" id="xml:lang-ne-lang"><h3>The value of the <code>xml:lang</code> attribute
1721      is different from the value of the <code>lang</code> attribute.</h3>
1722        <p>The value of the <code>xml:lang</code> attribute (either the
1723        <code>lang</code> attribute in the <code>xml</code> (i.e.
1724        <code>http://www.w3.org/XML/1998/namespace</code>) namespace, or
1725        the <code>xml:lang</code> attribute in no namespace) for the element has
1726        different value than that of the <code>lang</code> attribute in no
1727        namespace.</p>
1728    
1729        <p>For historical reason, there are two attributes applicable to HTML
1730        elements to specify language information of an element: <code>lang</code>
1731        and <code>xml:lang</code>.  In HTML documents, only <code>lang</code>
1732        attribute in no namespace is allowed and take effect; the
1733        <code>xml:lang</code> attribute in no namespace is ignored in HTML
1734        documents.  In XHTML documents, both <code>lang</code> and
1735        <code>xml:lang</code> attributes are allowed.</p>
1736    
1737        <p>In general, <em>only the <code>lang</code> attribute</em> need to be
1738        specified for an element.</p>
1739    
1740        <p>If both <code>lang</code> and <code>xml:lang</code> attributes are
1741        specified on the same element, their values must be the same value.</p>
1742      </div>
1743    
1744  </section>  </section>
1745    
1746  <section id="table-model-errors">  <section id="table-model-errors">
1747  <h2>Table Model Errors</h2>  <h2>Table Model Errors</h2>
1748    
1749  <div class="section table-model-error" id="table:colspan-creates-column-with-no-anchored-cell"><h3>This <code>colspan</code> attribute  <div class="section" id="cell-overlapping"><h3>Cell slot (<var>{text}</var>) is filled by
1750      multiple cells.</h3></div>
1751    
1752    <div class="section" id="colspan-creates-column-with-no-anchored-cell"><h3>This <code>colspan</code> attribute
1753    results in creating a table column that does not contain    results in creating a table column that does not contain
1754    any cell anchored to it.</h3></div>    any cell anchored to it.</h3></div>
1755    
1756  <div class="section table-model-error" id="table:no-cell-in-last-row"><h3>The table has no cell (<code>td</code> or  <div class="section" id="column-with-no-anchored-cell"><h3>This column has no anchored cell.</h3></div>
1757    
1758    <div class="section" id="table:no-cell-in-last-row"><h3>The table has no cell (<code>td</code> or
1759    <code>th</code>) in the last row.</h3></div>    <code>th</code>) in the last row.</h3></div>
1760    
1761  <div class="section table-model-error" id="table:rowspan-extends-table"><h3>This <code>rowspan</code> attribute  <div class="section" id="table:rowspan-extends-table"><h3>This <code>rowspan</code> attribute
1762    results in creating a table row that does not contain    results in creating a table row that does not contain
1763    any cell anchored to it.</h3>    any cell anchored to it.</h3>
1764      <p>The <code>rowspan</code> attribute value of the cell      <p>The <code>rowspan</code> attribute value of the cell
# Line 1086  p { Line 1777  p {
1777      a cell that spans between first and second rows.</p>      a cell that spans between first and second rows.</p>
1778    </div>    </div>
1779    
1780    <div class="section" id="row-with-no-anchored-cell"><h3>This row has no anchored cell.</h3></div>
1781    
1782    <div class="section" id="rowspan-creates-row-with-no-anchored-cell"><h3>This <code>rowspan</code> attribute
1783      results in creating a table row that does not contain
1784      any cell anchored to it.</h3></div>
1785    
1786    
1787  </section>  </section>
1788    
1789  <section id="imt-warnings">  <section id="imt-warnings">
1790  <h2>Internet Media Type Warnings</h2>  <h2>Internet Media Type Errors</h2>
1791    
1792    <div class="section" id="boundary:syntax-error"><h3>The specified value is not a valid value
1793      as a multipart boundary.</h3></div>
1794    
1795  <div class="section should" id="s:IMT:obsolete-subtype"><h3><code><var>{@}</var></code>: An <em>obsolete</em>  <div class="section" id="e4x:syntax-error"><h3>The specified value is not a valid value
1796    subtype is used.</h3></div>    for the attribute <code>e4x</code>.</h3></div>
1797    
1798  <div class="section should" id="s:IMT:private-subtype"><h3><code><var>{@}</var></code>: A private  <div class="section" id="IMT:attribute-syntax-error"><h3>The specified value,
1799    (<code>x-</code> or <code>x.</code>) subtype is used.</h3></div>    <code><var>{value}</var></code>, is syntactically not a valid
1800      attribute name.</h3></div>
1801    
1802  <div class="section should" id="s:IMT:unregistered-subtype"><h3><code><var>{@}</var></code>: The subtype is  <div class="section" id="IMT:composite"><h3>The specified media type is a composite
1803    not registered to IANA.</h3></div>    type, which is not allowed in this context.</h3></div>
1804    
1805    <div class="section" id="IMT:limited-use-subtype"><h3>An Internet Media Type whose intended usage
1806      is limited use, <code><var>{value}</var></code> is used.</h3></div>
1807    
1808    <div class="section" id="IMT:syntax-error"><h3>The specified value is not an Internet Media
1809      Type.</h3></div>
1810    
1811    <div class="section" id="IMT:obsolete-parameter"><h3>An obsolete parameter
1812      <code><var>{value}</var></code> is used.</h3></div>
1813    
1814    <div class="section" id="IMT:obsolete-subtype"><h3>An obsolete Internet Media Type
1815      <code><var>{value}</var></code> is used.</h3>
1816        <p>The specified Internet Media Type is registered with its intended
1817        usage as <i>OBSOLETE</i>.</p>
1818        
1819        <dl class="swtich">
1820        <dt>Media type <code>text/ecmascript</code></dt>
1821          <dd>Media type <code>text/ecmascript</code> is obsoleted in
1822          favor of <code>application/ecmascript</code>.  Note that
1823          <em><code>text/javascript</code></em> would be the better alternative
1824          in many cases.</dd>
1825        <dt>Media type <code>text/javascript</code></dt>
1826          <dd>Media type <code>text/javascript</code> is obsoleted by
1827          <abbr>IETF</abbr> with backward incompatible alternate
1828          <code>application/javascript</code> for architectural
1829          purity.<!-- @@ ref? -->  Those who prefer reality to academic
1830          purity <em>may ignore</em> this warning.</dd>
1831        </dl>
1832      </div>
1833    
1834    <div class="section" id="IMT:parameter-missing"><h3>Parameter <code><var>{text}</var></code> have to
1835      be specified for the Internet Media Type
1836      <code><var>{value}</var></code>.</h3></div>
1837    
1838    <div class="section" id="IMT:parameter-not-allowed"><h3>Parameter <code><var>{value}</var></code> is not
1839      allowed for this Internet Media Type.</h3></div>
1840    
1841    <div class="section" id="IMT:private-subtype"><h3>Use of a private Internet Media Type
1842      <code><var>{value}</var></code> is not encouraged.</h3></div>
1843    
1844    <div class="section" id="IMT:private-type"><h3>Use of a private type
1845      <code><var>{value}</var></code> is not encouraged.</h3></div>
1846    
1847    <div class="section" id="IMT:subtype-syntax-error"><h3>Value <code><var>{value}</var></code> is
1848      syntactically not a valid subtype value of an Internet Media Type.</h3></div>
1849    
1850    <div class="section" id="IMT:type-syntax-error"><h3>Value <code><var>{value}</var></code> is
1851      syntactically not a valid type.</h3></div>
1852    
1853    <div class="section" id="IMT:unknown-parameter"><h3>An unknown parameter <code><var>{value}</var></code>
1854      is used.  The conformance checker cannot determine whether use of this
1855      parameter is valid or not.</h3></div>
1856    
1857    <div class="section" id="IMT:unknown-subtype"><h3>An unknown Internet Media Type
1858      <code><var>{value}</var></code> is used.  At the time of the update of
1859      the conformance checker's Internet Media Type database, the subtype is
1860      not reigstered to the IANA registry.  The subtype, however, might be
1861      registerd to the IANA registry thereafter.  Please consult the IANA
1862      registry.</h3></div>
1863    
1864    <div class="section" id="IMT:unregistered-subtype"><h3>Use of an Internet Media Type
1865      <code><var>{value}</var></code> is not encouraged since it is not
1866      part of the IANA registry.</h3></div>
1867    
1868    <div class="section" id="IMT:unregistered-type"><h3>Use of a type
1869      <code><var>{value}</var></code> is not encouraged since it is not
1870      a standardized type.</h3></div>
1871    
1872    <div class="section" id="not-IMT"><h3>A value that is not an Internet Media Type
1873      is not allowed here.</h3></div>
1874    
1875  </section>  </section>
1876    
1877  <section id="uri-errors">  <section id="uri-errors">
1878  <h2>URI (or IRI) Errors</h2>  <h2>URL Errors</h2>
1879    
1880  <div class="section must" id="m:URI::syntax-error"><h3>The specified value is syntactically not an IRI  <div class="section" id="syntax-error:iri3987"><h3>The specified value is syntactically not an
1881      IRI.</h3></div>
1882    
1883    <div class="section" id="syntax-error:iriref3987"><h3>The specified value is syntactically not an IRI
1884    reference.</h3>    reference.</h3>
1885      <p>The specified value does not satisfy the syntactical requirements      <p>The specified value does not satisfy the syntactical requirements
1886      for IRI references.  The document is non-conforming.</p>      for IRI references.  The document is non-conforming.</p>
# Line 1120  p { Line 1895  p {
1895      </p>      </p>
1896    </div>    </div>
1897    
1898  </section>  <div class="section" id="syntax-error:rdfuriref"><h3>The specified value is syntactically not an RDF
1899      URI reference.</h3></div>
1900    
1901    <div class="section" id="syntax-error:uri2396"><h3>The specified value is syntactically not a
1902      URI according to RFC 2396.</h3></div>
1903    
1904    <div class="section" id="syntax-error:uri3986"><h3>The specified value is syntactically not a
1905      URI.</h3></div>
1906    
1907    <div class="section" id="URL:address-format"><h3>URL host address format
1908      <code><var>{text}</var></code> is not defined.</h3></div>
1909    
1910  <section id="uri-shoulds">  <div class="section" id="URL:default-port"><h3>Default port number should be omitted.</h3></div>
 <h2>URI (or IRI) Should-level Errors</h2>  
1911    
1912  <div class="section should" id="s:URI::dot-segment"><h3>A dot-segment (<code>.</code> or  <div class="section" id="URL:dot-segment"><h3>A dot-segment (<code>.</code> or
1913    <code>..</code>) occurs in an absolute reference.</h3>    <code>..</code>) occurs in an absolute reference.</h3>
1914      <p>Dot-segment (<code>.</code> or <code>..</code>) should      <p>Dot-segment (<code>.</code> or <code>..</code>) should
1915      not occur in an absolute reference.</p>      not occur in an absolute reference.</p>
# Line 1137  p { Line 1921  p {
1921      canonical form before it has been published.</p>      canonical form before it has been published.</p>
1922    </div>    </div>
1923    
1924  <div class="section should" id="s:URI::empty-path"><h3>This IRI does not end with  <div class="section" id="URL:empty-host"><h3>The host component of the URL is empty.</h3></div>
1925    a <code>/</code>.</h3></div>  
1926    <div class="section" id="URL:empty-path"><h3>The URL does not end with
1927      a <code>/</code> character.</h3></div>
1928    
1929    <div class="section" id="URL:empty-port"><h3>The port component of the URL is empty.</h3></div>
1930    
1931    <div class="section" id="URL-fragment-not-allowed"><h3>The fragment component of the URL is not
1932      allowed.</h3></div>
1933    
1934    <div class="section" id="URL:long-host"><h3>The host component of the URL
1935      is too long.</h3></div>
1936    
1937  <div class="section should" id="s:URI::lowercase-hexadecimal-digit"><h3>A lowercase hexadecimal digit is used  <div class="section" id="URL:lowercase-hexadecimal-digit"><h3>A lowercase hexadecimal digit is used
1938    in percent-encoding.</h3>    in percent-encoding.</h3>
1939      <p>The hexadecimal digit in percent-encoding string in the IRI      <p>The hexadecimal digit in percent-encoding string in the IRI
1940      is in lowercase.  Though the IRI <em>is</em> conforming,      is in lowercase.  Though the IRI <em>is</em> conforming,
1941      it should be in uppercase.</p>      it should be in uppercase.</p>
1942    </div>    </div>
1943    
1944  <div class="section should" id="s:URI::percent-encoded-unreserved"><h3>An unreserved character is  <div class="section" id="URL:non-DNS-host"><h3>The host component of the URL
1945      is not a DNS host name.</h3></div>
1946    
1947    <div class="section" id="URL:non-UTF-8-host"><h3>The host component of the URL
1948      is not encoded in UTF-8.</h3></div>
1949    
1950    <div class="section" id="URL:password"><h3>Password should not be included in a URL
1951      for the security.</h3></div>
1952    
1953    <div class="section" id="URL:percent-encoded-unreserved"><h3>An unreserved character is
1954    percent-encoded.</h3>    percent-encoded.</h3>
1955      <p>An unreserved character is percent-encoded in the IRI.      <p>An unreserved character is percent-encoded in the IRI.
1956      Though it <em>is</em> conforming, it should be in the      Though it <em>is</em> conforming, it should be in the
1957      decoded (or bare) form.</p>      decoded (or bare) form.</p>
1958    </div>    </div>
1959    
1960  <div class="section should" id="s:URI::uppercase-scheme-name"><h3>URI scheme name is in uppercase.</h3>  <div class="section" id="URL:uppercase-host"><h3>The host <code><var>{value}</var></code>
1961      should be spelt in lowercase.</h3></div>
1962    
1963    <div class="section" id="URL:uppercase-scheme-name"><h3>URL scheme name is in uppercase.</h3>
1964      <p>The scheme part of the IRI is written in uppercase letter.</p>      <p>The scheme part of the IRI is written in uppercase letter.</p>
1965    
1966      <p>Uppercase scheme names are not required to be processed      <p>Uppercase scheme names are not required to be processed
# Line 1172  p { Line 1978  p {
1978    
1979  </section>  </section>
1980    
1981    <section id="mq-errors">
1982    <h2>Media Query Errors</h2>
1983    
1984    <div class="section" id="mq-syntax-error"><h3>The specified value has a syntax error as a
1985      media query.</h3></div>
1986    
1987    <div class="section" id="unknown-media-type"><h3>Media type <code><var>{value}</var></code> is
1988      not supported by the conformance checker.</h3></div>
1989    
1990    </section>
1991    
1992    <section id="selectors-errors">
1993    <h2>Selectors Errors</h2>
1994    
1995    <div class="section" id="an+b-not-closed"><h3>Argument list of the pseudo-class is
1996      not closed by a <code>)</code> character.</h3></div>
1997    
1998    <div class="section" id="ab+b-not-integer"><h3>Numbers in the argument
1999      <code><var>a</var>n+<var>b</var></code> have to be integers.</h3></div>
2000    
2001    <div class="section" id="an+b-syntax-error"><h3>Argument <code><var>a</var>n+<var>b</var></code> is
2002      syntactically incorrect.</h3></div>
2003    
2004    <div class="section" id="attr-selector-not-closed"><h3>Attribute selector is not closed by
2005      a <code>]</code> character.</h3></div>
2006    
2007    <div class="section" id="lang-selector-not-closed"><h3>Argument list of the <code>:lang</code>
2008      selector is not closed by a <code>)</code> character.</h3></div>
2009    
2010    <div class="section" id="namespace-prefix:not-declared"><h3>Namespace prefix <code><var>{value}</var></code>
2011      is not declared.</h3></div>
2012    
2013    <div class="section" id="no-attr-local-name"><h3>Attribute local name is missing.</h3></div>
2014    
2015    <div class="section" id="no-attr-match"><h3>Attribute matching operator (e.g.
2016      <code>=</code>) is missing.</h3></div>
2017    
2018    <div class="section" id="no-attr-name"><h3>Attribute name is missing.</h3></div>
2019    
2020    <div class="section" id="no-attr-namespace-separator"><h3>Attribute namespace wildcard <code>*</code>
2021      is not followed by a <code>|</code> character.</h3></div>
2022    
2023    <div class="section" id="no-attr-value"><h3>Attribute value is missing.</h3></div>
2024    
2025    <div class="section" id="no-class-name-selector"><h3>Class name is missing.</h3></div>
2026    
2027    <div class="section" id="no-combinator"><h3>Combinator is missing.</h3></div>
2028    
2029    <div class="section" id="no-contains-string"><h3>No string is specified in the argument
2030      list of the <code>:-manakai-contains</code> pseudo-class
2031      selector.</h3></div>
2032    
2033    <div class="section" id="no-lang-tag"><h3>Language tag argument is missing.</h3></div>
2034    
2035    <div class="section" id="no-local-name-selector"><h3>Local name part of the type selector (or
2036      <code>*</code> for the universal selector) is missing.</h3></div>
2037    
2038    <div class="section" id="no-pseudo-class-name"><h3>Pseudo-class name is missing.</h3></div>
2039    
2040    <div class="section" id="no-pseudo-element-name"><h3>Pseudo-element name is missing.</h3></div>
2041    
2042    <div class="section" id="no-sss"><h3>Sequence of simple selectors is
2043      expected.</h3></div>
2044    
2045    <div class="section" id="not-not-closed"><h3>Argument list of the <code>:not</code> selector
2046      is not closed by a <code>)</code> character.</h3></div>
2047    
2048    <div class="section" id="ss-after-pseudo-element"><h3>Simple selector is not allowed after a
2049      pseudo element.</h3></div>
2050    
2051    <div class="section" id="unknown-pseudo-class"><h3>Pseudo-class <code>:<var>{value}</var></code>
2052      is not supported by the conformance checker.</h3></div>
2053    
2054    <div class="section" id="unknown-pseudo-element"><h3>Pseudo-element <code>::<var>{value}</var></code>
2055      is not supported by the conformance checker.</h3></div>
2056    
2057    </section>
2058    
2059    <section id="css-errors">
2060    <h2>CSS Errors</h2>
2061    
2062    <div class="section" id="at-rule-not-allowed"><h3>An <code>@<var>{text}</var></code> rule is not
2063      allowed here.</h3></div>
2064    
2065    <div class="section" id="at-rule-syntax-error"><h3>The <code>@<var>{text}</var></code> rule is
2066      syntactically incorrect.</h3></div>
2067    
2068    <div class="section" id="block-not-closed"><h3>Block is not closed before the end of
2069      file.</h3></div>
2070    
2071    <div class="section" id="CSS-duplication"><h3>Component <code>&lt;<var>{text}</var>&gt;</code> is
2072      already specified.</h3></div>
2073    
2074    <div class="section" id="CSS-cursor-hand"><h3>Value <code>hand</code> is not valid as
2075      <code>&lt;'cursor'&gt;</code>.</h3></div>
2076    
2077    <div class="section" id="CSS-syntax-error"><h3>Specified value is syntactically not a correct
2078      <code>&lt;<var>{text}</var>&gt;</code>.</h3></div>
2079    
2080    <div class="section" id="no-declaration-block"><h3>No declaration block is found after a group of
2081      selectors.</h3></div>
2082    
2083    <div class="section" id="no-property-colon"><h3>A <code>:</code> character is missing after
2084      a property name.</h3></div>
2085    
2086    <div class="section" id="no-property-name"><h3>Property name is expected.</h3></div>
2087    
2088    <div class="section" id="no-property-semicolon"><h3>A <code>;</code> character is missing at the
2089      end of the property.</h3></div>
2090    
2091    <div class="section" id="priority-syntax-error"><h3>Priority part of the declaration is syntactically
2092      incorrect.</h3></div>
2093    
2094    <div class="section" id="unknown-at-rule"><h3>The <code>@<var>{value}</var></code> rule is
2095      not supported by the conformance checker.</h3></div>
2096    
2097    <div class="section" id="unknown-property"><h3>Property <code><var>{value}</var></code> is
2098      not supported by the conformance checker.</h3></div>
2099    
2100    </section>
2101    
2102  <section id="cache-manifest-errors">  <section id="cache-manifest-errors">
2103  <h2>Cache Manifest Errors</h2>  <h2>Cache Manifest Errors</h2>
2104    
2105  <div class="section must" id="m:not-manifest"><h3>This document is not a cache manifest.</h3>  <div class="section" id="both-in-entries-and-whitelist"><h3>This URL is found both in the explicit or
2106      fallback entries and in the online whitelist.</h3></div>
2107    
2108    <div class="section" id="different-origin-from-manifest"><h3>The specified URL has different origin from
2109      the manifest.</h3></div>
2110    
2111    <div class="section" id="different-scheme-from-manifest"><h3>The scheme component of the URL is
2112      different from that of the manifest URL.  The URL is ignored.</h3></div>
2113    
2114    <div class="section" id="duplicate-oc-namespace"><h3>This oppotunistic caching namespace is already
2115      specified.</h3></div>
2116    
2117    <div class="section" id="no-fallback-entry-URL"><h3>Fallback entry URL is missing.</h3></div>
2118    
2119    <div class="section" id="not-manifest"><h3>This document is not a cache manifest.</h3>
2120      <p>The specified document is <em>not</em> a cache manifest.      <p>The specified document is <em>not</em> a cache manifest.
2121      The document is non-conforming.</p>      The document is non-conforming.</p>
2122    
# Line 1187  p { Line 2128  p {
2128      (exactly one space character between      (exactly one space character between
2129      <code>CACHE</code> and <code>MANIFEST</code>).</p>      <code>CACHE</code> and <code>MANIFEST</code>).</p>
2130    </div>    </div>
2131    
2132    <div class="section" id="same-as-manifest-URL"><h3>This URL is same as the manifest URL.</h3></div>
2133    
2134  </section>  </section>
2135    
2136  <section id="information">  <section id="information">
2137  <h2>Stability Information</h2>  <h2>Stability Information</h2>
2138    
2139  <div class="section level-i" id="i:status:cr:element"><h3>This element is in the  <div class="section" id="deprecated:attr"><h3>This attribute is deprecated.</h3></div>
2140    
2141    <div class="section" id="deprecated:element"><h3>This element is deprecated.</h3></div>
2142    
2143    <div class="section" id="status:cr:element"><h3>This element is in the
2144    <strong>call for implementation</strong> stage.</h3>    <strong>call for implementation</strong> stage.</h3>
2145      <p>The element is in the call for implementation stage.</p>      <p>The element is in the call for implementation stage.</p>
2146            
# Line 1205  p { Line 2153  p {
2153      (W3C Candidate Recommendation) belong to this class.</p>      (W3C Candidate Recommendation) belong to this class.</p>
2154    </div>    </div>
2155    
2156  <div class="section level-i" id="i:status:lc:element"><h3>This element is in the <strong>last  <div class="section" id="status:lc:element"><h3>This element is in the <strong>last
2157    call for comments</strong> stage.</h3>    call for comments</strong> stage.</h3>
2158      <p>The element is in the last call for comments stage.</p>      <p>The element is in the last call for comments stage.</p>
2159            
# Line 1219  p { Line 2167  p {
2167      defined by HTML5 belong to this class.</p>      defined by HTML5 belong to this class.</p>
2168    </div>    </div>
2169    
2170  <div class="section level-i" id="i:status:wd:element"><h3>This element is documented in a <strong>working  <div class="section" id="status:wd:element"><h3>This element is documented in a <strong>working
2171    draft</strong>.</h3>    draft</strong>.</h3>
2172      <p>The element is documented in a working or editor's draft      <p>The element is documented in a working or editor's draft
2173      and not yet completed.</p>      and not yet completed.</p>
# Line 1231  p { Line 2179  p {
2179      <p>Most of new elements defined by HTML5 belong to this class.</p>      <p>Most of new elements defined by HTML5 belong to this class.</p>
2180    </div>    </div>
2181    
2182  <div class="section level-i" id="i:status:non-standard:element"><h3>This element is <strong>not part of any  <div class="section" id="status:non-standard:element"><h3>This element is <strong>not part of any
2183    standard</strong> the conformance checker knows.</h3>    standard</strong> the conformance checker knows.</h3>
2184      <p>The element is not part of any standard or draft the conformance      <p>The element is not part of any standard or draft the conformance
2185      checker is aware of.</p>      checker is aware of.</p>
# Line 1239  p { Line 2187  p {
2187      <p>The element should not be used for any practical purpose unless      <p>The element should not be used for any practical purpose unless
2188      there is really a standard that defines the element.</p>      there is really a standard that defines the element.</p>
2189    </div>    </div>
2190    
2191    <div class="section" id="status:cr:attr"><h3>This attribute is in the
2192      <strong>call for implementation</strong> stage.</h3>
2193        <p>The attribute is in the call for implementation stage.</p>
2194        
2195        <p>Usually, using the attribute is safe.  However, it is a new feature
2196        so that it might not be implemented correctly.  If it is found that
2197        the feature is hard or impossible to implement, the feature
2198        might be revised, or in some case it might be dropped.</p>
2199      </div>
2200    
2201    <div class="section" id="status:lc:attr"><h3>This attribute is in the <strong>last
2202      call for comments</strong> stage.</h3>
2203        <p>The attribute is in the last call for comments stage.</p>
2204        
2205        <p>The attribute is relatively mature, though the standardization
2206        is not done yet.  It may be used for experiments.  Since it is a new
2207        feature, it might not be implemented correctly or at all.  If it is
2208        found that the feature is hard or impossible to implement, the feature
2209        might be revised or might be dropped.</p>
2210      </div>
2211    
2212    <div class="section" id="status:wd:attr"><h3>This attribute is documented in a <strong>working
2213      draft</strong>.</h3>
2214        <p>The attribute is documented in a working or editor's draft
2215        and not yet completed.</p>
2216        
2217        <p>The attribute should not be used for any practical purpose.
2218        The feature might be drastically changed later or might be
2219        entirely removed.</p>
2220      </div>
2221    
2222    <div class="section" id="status:non-standard:attr"><h3>This attribute is <strong>not part of any
2223      standard</strong> the conformance checker knows.</h3>
2224        <p>The attribute is not part of any standard or draft the conformance
2225        checker is aware of.</p>
2226        
2227        <p>The attribute should not be used for any practical purpose unless
2228        there is really a standard that defines the attribute.</p>
2229      </div>
2230    </section>
2231    
2232    <section id="langtag-errors">
2233    <h2>Language Tag Errors</h2>
2234    
2235    <div class="section" id="langtag:extension:duplication"><h3>There is another extension subtag
2236      <code><var>{value}</var></code>.</h3></div>
2237    
2238    <div class="section" id="langtag:illegal"><h3>Subtag <code><var>{value}</var></code> is
2239      syntactically invalid.</h3></div>
2240    
2241    <div class="section" id="langtag:language:case"><h3>It is a good practice to represent ISO 639-1
2242      language code <code><var>{value}</var></code> in lowercase.</h3></div>
2243    
2244    <div class="section" id="langtag:language:mul"><h3>Langauge tag <code>mul</code> should not be
2245      used.</h3></div>
2246    
2247    <div class="section" id="langtag:language:nosemantics"><h3>No semantics is defined for language subtag
2248      <code><var>{value}</var></code>.</h3></div>
2249    
2250    <div class="section" id="langtag:language:syntax"><h3>The language subtag <code><var>{value}</var></code>
2251      is syntactically invalid.</h3></div>
2252    
2253    <div class="section" id="langtag:language:und"><h3>Langauge tag <code>und</code> should not be
2254      used.</h3></div>
2255    
2256    <div class="section" id="langtag:private"><h3>It would be better if a private use language
2257      tag (<code><var>{value}</var></code>) is not used.</h3></div>
2258    
2259    <div class="section" id="langtag:privateuse:syntax"><h3>Private use subtag <code><var>{value}</var></code>
2260      is syntactically invalid.</h3></div>
2261    
2262    <div class="section" id="langtag:region:case"><h3>It is a good practice to represent ISO 3166
2263      country code <code><var>{value}</var></code> in uppercase.</h3></div>
2264    
2265    <div class="section" id="langtag:region:nosemantics"><h3>No semantics is defined for region subtag
2266      <code><var>{value}</var></code>.</h3></div>
2267    
2268    <div class="section" id="langtag:region:private"><h3>Use of private use country code
2269      <code><var>{value}</var></code> is not allowed.</h3></div>
2270    
2271    </section>
2272    
2273    <section id="rdfxml-errors">
2274    <h2>RDF/XML Errors</h2>
2275    
2276    <div class="section" id="bad-rdf-namespace"><h3>The namespace URI of an element that
2277      represents an RDF concept must be
2278      <code>http://www.w3.org/1999/02/22-rdf-syntax-ns#</code>.</h3></div>
2279    
2280    <div class="section" id="duplicate-rdf-id"><h3>The specified value is already used as an
2281      ID.</h3></div>
2282    
2283    <div class="section" id="duplicate-unqualified-attr"><h3>Both unqualified attribute and namespace‐qualified
2284      RDF attribute are specified, which is not allowed.</h3></div>
2285    
2286    <div class="section" id="parse-type-other"><h3>An invalid value is specified to
2287      the <code>parseType</code> attribute.</h3></div>
2288    
2289    <div class="section" id="second-node-element"><h3>There is another element, such that
2290      this element is not allowed.</h3></div>
2291    
2292    <div class="section" id="unqualified-attr"><h3>Unqualified attribute is not allowed.</h3></div>
2293    
2294    <div class="section" id="unqualified-rdf-attr"><h3>RDF attribute should be
2295      namespace‐qualified.</h3></div>
2296    
2297  </section>  </section>
2298    
2299  <section id="unsupported-messages">  <section id="unsupported-messages">
2300  <h2><i>Unsupported</i> Messages</h2>  <h2><i>Unsupported</i> Messages</h2>
2301    
2302  <div class="section unsupported" id="unsupported:element"><h3>Conformance checking for element  <div class="section" id="unknown-element"><h3>Conformance checking for element
2303    <code><var>{local-name}</var></code> is not supported; <em>it might or    <code><var>{local-name}</var></code> is not supported; <em>it might or
2304    might not be conforming</em>.</h3>    might not be conforming</em>.</h3>
2305      <p>The conformant checker does not support the element.      <p>The conformant checker does not support the element.
2306      It cannot determine whether the document is conforming or not.</p>      It cannot determine whether the document is conforming or not.</p>
2307    </div>    </div>
2308    
2309  <div class="section unsupported" id="unsupported:attribute"><h3>Conformance checking for attribute  <div class="section" id="unknown-attribute"><h3>Conformance checking for attribute
2310    <code><var>{local-name}</var></code> of element    <code><var>{local-name}</var></code> of element
2311    <code><var>{element-local-name}</var></code> is not supported;    <code><var>{element-local-name}</var></code> is not supported;
2312    <em>it might or might not be conforming</em>.</h3>    <em>it might or might not be conforming</em>.</h3>
# Line 1259  p { Line 2314  p {
2314      It cannot determine whether the document is conforming or not.</p>      It cannot determine whether the document is conforming or not.</p>
2315    </div>    </div>
2316    
2317  <div class="section unsupported" id="unsupported:link-type"><h3>Link type <code><var>$0</var></code> is not  <div class="section" id="unknown-link-type"><h3>Link type <code><var>{value}</var></code> is not
2318    standardized or registered at the time of the release of the conformance    standardized or registered at the time of the release of the conformance
2319    checker; <em>it is non-conforming unless it now has been    checker; <em>it is non-conforming unless it now has been
2320    registered</em>.</h3>    registered</em>.</h3>
# Line 1281  p { Line 2336  p {
2336      </dl>      </dl>
2337    </div>    </div>
2338    
2339  <div class="section unsupported" id="unsupported:event-handler"><h3>Conformance checking for event handler attribute  <div class="section" id="event-handler"><h3>Conformance checking for event handler attribute
2340      is not supported; <em>it might or might not be conforming.</em></h3></div>
2341    
2342    <div class="section" id="media-query"><h3>Conformance checking for media query
2343    is not supported; <em>it might or might not be conforming.</em></h3></div>    is not supported; <em>it might or might not be conforming.</em></h3></div>
2344    
2345  <div class="section unsupported" id="unsupported:media-query"><h3>Conformance checking for media query  <div class="section" id="addr-spec-not-supported"><h3>Conformance checking for an <code>addr-spec</code>
2346    is not supported; <em>it might or might not be conforming.</em></h3></div>    is not supported; <em>it might or might not be conforming.</em></h3></div>
2347    
2348  <div class="section unsupported" id="unsupported:script"><h3>Conformance checking for script  <div class="section" id="XML-script-lang"><h3>Conformance checking for script
2349    language <code><var>$0</var></code> is not supported;    language <code><var>{text}</var></code> is not supported;
2350    <em>it might or might not be conforming.</em></h3></div>    <em>it might or might not be conforming.</em></h3></div>
2351    
2352  <div class="section unsupported" id="unsupported:style"><h3>Conformance checking for style  <div class="section" id="XML-style-lang"><h3>Conformance checking for style
2353    language <code><var>$0</var></code> is not supported;    language <code><var>{text}</var></code> is not supported;
2354    <em>it might or might not be conforming.</em></h3></div>    <em>it might or might not be conforming.</em></h3></div>
2355    
2356    <div class="section" id="atom|content-not-supported"><h3>Conformance checking for an Atom
2357      <code>content</code> element with <code>type</code>
2358      <code><var>{text}</var></code> is not supported.</h3></div>
2359    
2360    <div class="section" id="help-not-available"><h3>No more information is available.</h3>
2361        <p>No more information is available for this topic.</p>
2362      </div>
2363    
2364  </section>  </section>
2365    
2366    
2367    
 <section id="levels">  
 <h2>Error Levels</h2>  
2368    
2369  <table id="levels-table">  
2370  <thead>  
2371  <tr><th scope="col">Level</th>  
2372  <th scope="col">Conforming?</th>  
2373  <th scope="col">Description</th>  
2374  </tr>  
2375  </thead>  
2376  <tbody>  
2377  <tr class="level-m" id="level-m">  
2378  <th scope="row"><em class="rfc2119">MUST</em>‐level error</th>  
2379  <td>Non‐conforming.</td>  
2380  <td>A violation to a hard requirement of the specification.  
2381  The document is non‐conforming.</td>  
2382  </tr>  
2383  <tr class="level-s" id="level-s">  
2384  <th scope="row"><em class="rfc2119">SHOULD</em>‐level error</th>  
2385  <td>Non‐conforming, but <em>in some case</em>  
2386  conforming.</td>  
2387  <td>A violation to a requirement of the specification.  
2388  The violation might be legitimize in some case.  Otherwise,  
2389  the document is non‐conforming.</td>  
2390  </tr>  
2391  <tr class="level-w" id="level-w">  
2392  <th scope="row">Warning</th>  
2393  <td>Conforming.</td>  
2394  <td>A warning is an advice from the conformance checker to avoid  
2395  to solve a problem in a confusing or possibly wrong way.  
2396  It does not affect to the conformance of the document, and  
2397  may sometimes be inappropriate.</td>  
2398  </tr>  
2399  <tr class="level-i" id="level-i">  
2400  <th scope="row">Information</th>  
2401  <td>Conforming.</td>  
2402  <td>An informational message just provides an additional information  
2403  on the feature used in the document or the status of the retrieval  
2404  or so on.  
2405  It does not affect to the conformance of the document.</td>  
2406  </tr>  
2407  <tr class="level-u" id="level-u">  
2408  <th scope="row">Not supported</th>  
2409  <td><em>Unknown</em>.</td>  
2410  <td>Some feature that is not supported by the conformance checker  
2411  is used in the document.</td>  
2412  </tr>  
2413  </tbody>  
2414  </table>  
2415  </section>  
2416    
2417    
2418    
2419    
2420    
2421    
2422    
2423    
2424    
2425    
2426    
2427    
2428    
2429    
2430    
2431    
2432    
2433    
2434    
2435    
2436    
2437    
2438    
2439    
2440    
2441    
2442    
2443    
2444    
2445    
2446    
2447    
2448    
2449    
2450    
2451    
2452    
2453    
2454    
2455    
2456    
2457    
2458    
2459    
2460    
2461    
2462    
2463    
2464    
2465    
2466    
2467    
2468    
2469    
2470    
2471    
2472    
2473    
2474    
2475    
2476    
2477    
2478    
2479    
2480    
2481    
2482    
2483    
2484    
2485    
2486    
2487    
2488    
2489    
2490    
2491    
2492    
2493    
2494    
2495    
2496    
2497    
2498    
2499    
2500    
2501    
2502    
2503    
2504    
2505    
2506    
2507    
2508    
2509    
2510    
2511    
2512    
2513    
2514    
2515    
2516    
2517    
2518    
2519    
2520    
2521    
2522    
2523    
2524    
2525    
2526    
2527    
2528    
2529    
2530    
2531    
2532    
2533    
2534    
2535    
2536    
2537    
2538    
2539    
2540    
2541    
2542    
2543    
2544    
2545    
2546    
2547    
2548    
2549    
2550    
2551    
2552    
2553    
2554    
2555    
2556    
2557    
2558    
2559    
2560    
2561    
2562    
2563    
2564    
2565    
2566    
2567    
2568    
2569    
2570    
2571    
2572    
2573    
2574    <div class="section" id="Error-level-m"><h3><a href="../error-description#Error-level-m" rel="help"><em class="rfc2119">MUST</em>‐level
2575            error</a></h3>
2576        <p>A violation to a hard requirement of the specification.
2577        The document is non‐conforming.</p>
2578      </div>
2579    
2580    <div class="section" id="Error-level-s"><h3><a href="../error-description#Error-level-s" rel="help"><em class="rfc2119">SHOULD</em>‐level
2581            error</a></h3>
2582        <p>A violation to a requirement of the specification.
2583        The violation might be legitimize in some case.  Otherwise,
2584        the document is non‐conforming.</p>
2585      </div>
2586    
2587    <div class="section" id="Error-level-w"><h3><a href="../error-description#Error-level-w" rel="help">Warning</a></h3>
2588        <p>A warning is an advice from the conformance checker
2589        to avoid solving a problem in a confusing or possibly wrong way.
2590        It does not affect to the conformance of the document, and
2591        may sometimes be inappropriate.</p>
2592      </div>
2593    
2594    <div class="section" id="Error-level-i"><h3><a href="../error-description#Error-level-i" rel="help">Information</a></h3>
2595        <p>An informational message just provides an additional information
2596        on the feature used in the document or the status of the retrieval
2597        or so on.
2598        It does not affect to the conformance of the document.</p>
2599      </div>
2600    
2601    <div class="section" id="Error-level-u"><h3><a href="../error-description#Error-level-u" rel="help">Not
2602          supported</a></h3>
2603        <p>Some feature that is not supported by the conformance checker
2604        is used in the document.</p>
2605      </div>
2606    
2607  <section id="license">  <section id="license">
2608  <h2>License of This Document</h2>  <h2>License of This Document</h2>
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