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revision 1.3 by wakaba, Mon Jul 16 10:55:11 2007 UTC revision 1.42 by wakaba, Thu Dec 11 03:22:56 2008 UTC
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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    
 <section id="html5-tokenize-error">  
 <h2>HTML5 Parse Errors in Tokenization Stage</h2>  
15    
 <div class="section parse-error" id="after-html"><h3>Tag <code>&lt;<var>$0</var>&gt;</code>  
   is not allowed after the end tag <code>&lt;/html&gt;</code>.</h3>  
     <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>  
16    
17      <p>Any content of the document other than comments  <div class="section" id="WebHACC:Heading"><h3>
18      must be put into the <code>html</code> element.</p>      
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>    </div>
31    
32  <div class="section tokenize-error" id="bare-ero"><h3>The <code>&amp;</code> character must  <section id="character-encoding-layer">
33    introduce a reference.</h3>  <h2>Character Encoding Layer Errors</h2>
34      <p>An <code>&amp;</code> (<code>U+0026</code>  
35      <code class="charname">AMPERSAND</code>) character which  <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>
57    
58    <section id="html5-character-encoding">
59    <h2>HTML5 Character Encoding Errors</h2>
60    
61    <div class="section" id="charset:not-supported"><h3>Character encoding <code><var>{value}</var></code>
62      is not supported and the explicit character encoding specification is
63      ignored.  The result of the conformance checking might be
64      <em>wrong</em>.</h3></div>
65    
66    <div class="section" id="disallowed-character-encoding"><h3>Character encoding <code><var>{text}</var></code>
67      is not allowed for <abbr>HTML</abbr> document.</h3>
68        <p>The character encoding used for the document is not allowed
69        for <abbr>HTML</abbr> document.  The document is non‐conforming.</p>
70      </div>
71    
72    <div class="section" id="bad-character-encoding"><h3>Character encoding <code><var>{text}</var></code>
73      should not be used for <abbr>HTML</abbr> document.</h3>
74        <p>The character encoding used for the document is not recommended
75        for <abbr>HTML</abbr> document.  The document is non‐conforming
76        unless there is any good reason to use that encoding.</p>
77      </div>
78    
79    <div class="section" id="non-utf-8-character-encoding"><h3>Use of UTF-8 is encouraged (this document
80      is encoded in <code><var>{text}</var></code>).</h3>
81        <p>Use of UTF-8 as the character encoding of the document is encouraged,
82        though the use of another character encoding is still conforming.</p>
83      </div>
84    
85    <div class="section" id="character-encoding-unchecked"><h3>Conformance for character encoding requirements
86      cannot be checked, since the input is not a byte stream.</h3>
87        <p>The conformance checker cannot detect whether the input document
88        met the requirements on character encoding, since the document
89        is not inputed as a serialized byte sequence.  The document is
90        not conforming if it is not encoded in an appropriate character
91        encoding with appropriate labeling.</p>
92      </div>
93    
94    <div class="section" id="no-character-encoding-declaration"><h3>There is no character encoding
95      declaration.</h3>
96        <p>The document does not contain a character encoding
97        declaration.  Unless the character encoding is explicitly
98        specified in lower‐level protocol, e.g. in <abbr>HTTP</abbr>,
99        or is implied by <abbr>BOM</abbr>, there must be a character
100        encoding declaration.  The document is non‐conforming.</p>
101    
102        <p>The long character encoding declaration syntax
103        <code class="html bad example">&lt;meta http-equiv="Content-Type" content="text/html; charset=<var>charset-name</var>"&gt;</code>
104        is obsolete.  The new syntax is:</p>
105        <pre class="html example">
106    <code>&lt;meta charset="<var>charset-name</var>"&gt;</code></pre>
107    
108        <p>Note that the <code>encoding</code> declaration in <abbr>XML</abbr>
109        declaration has no effect for <abbr>HTML</abbr> document.</p>
110      </div>
111    
112    <div class="section" id="non-ascii-superset"><h3>No character encoding metadata is found
113      in lower‐level protocol nor is there <abbr>BOM</abbr>, while
114      character encoding <code><var>{text}</var></code>
115      is not a superset of <abbr>ASCII</abbr>.</h3>
116        <p>The document is not labeled with character encoding name
117        in lower‐level protocol, e.g. in <abbr>HTTP</abbr>, and
118        the document is not begin with <abbr>BOM</abbr>.  In addition,
119        the character encoding of the document is not a superset of
120        <abbr>ASCII</abbr>.  The document is non‐conforming.</p>
121    
122        <p>Unless there is a <abbr>BOM</abbr>, the character encoding
123        for the document must be specified in e.g. <abbr>HTTP</abbr>‐level,
124        as:</p>
125        <pre class="http example">
126    <code>Content-Type: text/html; charset=<var>charset-name</var></code></pre>
127    
128        <p>Existence of <abbr>HTML</abbr> character encoding declaration, i.e.
129        <code class="html example">&lt;meta charset="<var>charset-name</var>"&gt;</code>,
130        does not allow to omit <code>charset</code> parameter
131        for <abbr>HTML</abbr> document encoded in non‐<abbr>ASCII</abbr>
132        compatible encoding.</p>
133    
134        <p>Character encodings <code>Shift_JIS</code>, <code>Windows-31J</code>,
135        and <code>ISO-2022-JP</code> are <em>not</em> a superset of
136        <abbr>ASCII</abbr> for the purpose of <abbr>HTML</abbr> conformance.</p>
137      </div>
138    
139    <div class="section" id="sniffing:chardet"><h3>Character encoding of this document is sniffed
140      as <code><var>{text}</var></code> (Sniffed 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="sniffing:default"><h3>Character encoding of this document is defaulted
145      to <code><var>{text}</var></code> because no explicit specification
146      for the character encoding of this document is found in the transfer
147      procotol headers.</h3></div>
148    
149    <div class="section" id="chardecode:fallback"><h3>Results might be <em>wrong</em>, since the
150      conformance checker cannot find an appropriate decoder for the character
151      encoding used for the document.</h3>
152        <p>The conformance checker cannot find an appropriate decoder for
153        the character encoding used to encode characters in the document.</p>
154    
155        <p>This error is raised if:</p>
156        <ul>
157        <li>the conformance checker cannot find any decoder for the character
158        encoding in use, but it knows that the encoding is similar to another
159        character encoding, such that it uses the decoder for that character
160        encoding, and therefore some octets might be interpreted incorrectly,
161        or,</li>
162        <li>the conformance checker find a decoder for the character encoding
163        in use, but it does not know whether the decoder is conforming to the
164        relevant specification or not, and therefore some octets might be
165        interpreted incorrectly.</li>
166        </ul>
167    
168        <p>In either case, the result shown by the conformance checker might
169        contain wrong errors caused by errorneous decoder or might not contain
170        errors that should be raised if an appropriate decoder is used.</p>
171    
172        <!-- TODO: add advise that either install relevant modules or
173             join the developmenet of the modules... -->
174      </div>
175    
176    <div class="section" id="chardecode:no-error"><h3>Conformance error checking for the character
177      encoding <code><var>{text}</var></code> is not supported.</h3></div>
178    
179    <div class="section" id="charset-label:matching"><h3>Sniffed character encoding
180      <code><var>{text}</var></code> is same as the character encoding specified
181      in the character encoding declaration.  This is <em>not</em> an
182      error.</h3></div>
183    
184    <div class="section" id="charset-label-detected"><h3>While parsing the document as
185      <code><var>{text}</var></code>, a character encoding declaration specifying
186      a different character encoding is found.  The document
187      is reparsed.</h3>
188        <p>While parsing a document in a character encoding,
189        a character encoding declaration which declares the character
190        encoding of the document as another character encoding is found.
191        The occurence of this warning itself does not make the document
192        non‐conforming.  However, the failure of the first attempt to
193        to detect the character encoding might be a result of non‐conformance
194        of the document.</p>
195    
196        <p>The document will be reparsed from the beginning.  Some error
197        or warning might be reported again.</p>
198    
199        <p>These are suggestions to avoid this warning:</p>
200        <ul>
201        <li>Specify <code>charset</code> parameter in the <code>Content-Type</code>
202        field in the <abbr>HTTP</abbr> header, as:
203        <pre class="HTTP example">
204    <code>Content-Type: text/html; charset="<var>charset-name</var>"</code></pre></li>
205        <li>Put the character encoding declaration
206        (<code class="html example">&lt;meta charset="<var>charset-name</var>"&gt;</code>)
207        just after <code class="html example">&lt;head&gt;</code> start tag.</li>
208        <li>Use <code>UTF-8</code>.</li>
209        </ul>
210      </div>
211    </section>
212    
213    <section id="character-set-layer">
214    <h2>Coded Character Set Layer Errors</h2>
215    
216    <div class="section" id="NULL"><h3>The <code class="charname">NULL</code> character
217      is not allowed.</h3></div>
218    
219    <div class="section" id="control-char"><h3>Code point <code><var>{text}</var></code> is
220      not allowed.</h3></div>
221    
222    <div class="section" id="nonchar"><h3>Noncharacter <code><var>{text}</var></code>
223      is found in the input stream.</h3>
224        <p>Noncharacter code points are used in the input stream.</p>
225    
226        <p>Noncharacter code points are reserved for internal processings.
227        Their use for information interchanges are forbidden.</p>
228    
229        <p>In addition, they are not allowed in HTML document.</p>
230        <!-- "permanently undefined Unicode characters" in HTML5. -->
231      </div>
232    
233    <div class="section" id="non-unicode"><h3>Character <code><var>{text}</var></code> is not
234      a Unicode character.</h3></div>
235    
236    <div class="section" id="unicode-deprecated"><h3>Use of character <code><var>{text}</var></code>
237      is deprecated.</h3></div>
238    
239    <div class="section" id="unicode-discouraged"><h3>Use of character <code><var>{text}</var></code>
240      is discouraged.</h3></div>
241    
242    <div class="section" id="unicode-not-preferred"><h3>Code point <code><var>{text}</var></code>
243      is not the preferred representation of that character.</h3></div>
244    
245    <div class="section" id="unicode-should"><h3>Character <code><var>{text}</var></code>
246      should not be used in many cases.</h3></div>
247    
248    </section>
249    
250    <section id="html5-tokenize-error">
251    <h2>HTML5 Parse Errors in Tokenization Stage</h2>
252    
253    <div class="section" id="bad-attribute-name"><h3>Attribute name cannot contain characters
254      <code>"</code>, <code>'</code>, and <code>=</code>.</h3></div>
255    
256    <div class="section" id="bad-attribute-value"><h3>Attribute value must be quoted by <code>"</code>
257      or <code>'</code> if it contains a <code>"</code>, <code>'</code>, or
258      <code>=</code> character.</h3>
259        <p>In an unquoted attribute value, a character <code>"</code>
260        (<code>U+0022</code> <code class="charname">QUOTATION MARK</code>),
261        <code>'</code> (<code>U+0026</code>
262        <code class="charname">APOSTROPHE</code>), or <code>=</code>
263        (<code>U+003D</code> <code class="charname">EQUAL SIGN</code>)
264        is contained.  These characters are not allowed in unquoted attribute
265        values, since they are used to quote attribute values or to separate
266        attribute name and value.</p>
267    
268        <p>This error is also raised if one try to use empty attribute
269        value like <code class="html bad example">&lt;foo bar= baz=&gt;</code>;
270        in this example, <code class="html bad example">baz=</code> is
271        treated as an invalid attribute value for the attribute
272        <code class="html bad example">bar</code>, not as another attribute.</p>
273      </div>
274    
275    <div class="section" id="bare-ero"><h3>The <code>&amp;</code> character must
276      be escaped as <code class="html example">&amp;amp;</code>.</h3>
277        <p>An <code>&amp;</code> character which
278      is not part of any reference appears in the input stream.      is not part of any reference appears in the input stream.
279      The document is non-conforming.</p>      The document is non‐conforming.</p>
280    
281        <p><em>Any <code>&amp;</code> character in URI (or IRI)
282        must be escaped as <code class="example">&amp;amp;</code>.</em></p>
283    
284      <p>The <code>&amp;</code> character must      <p>The <code>&amp;</code> character must
285      be the first character of a reference:      be the first character of a reference:
286        <dl>        <dl class="switch">
287        <dt>Named entity reference</dt>        <dt>Named entity reference</dt>
288            <dd><pre class="html example">            <dd><pre class="html example">
289  <code>&amp;<var>entity-name</var>;</code></pre>  <code>&amp;<var>entity-name</var>;</code></pre>
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309      </p>      </p>
310    </div>    </div>
311    
312  <div class="section tokenize-error" id="bare-nero"><h3>The decimal representation of the code position  <div class="section" id="bare-etago"><h3>A <code>&lt;/</code> string is not followed
313      by a tag name.</h3>
314        <p>There is a <code>&lt;</code> (<code>U+003C</code>
315        <code class="charname">LESS-THAN SIGN</code>) character
316        immediately followed by a <code>/</code> (<code>U+005F</code>
317        <code>SOLIDUS</code>) character, which is not part
318        of any end tag, in the input stream.  The document
319        is non-conforming.</p>
320    
321        <p>The <code>&lt;/</code> sequence immediately followed
322        by an <abbr title="End of file pseudo-character">EOF</abbr> is
323        interpreted as a string data of <code>&lt;/</code>.</p>
324    
325        <p>The <code>&lt;/</code> sequence as string data must
326        be escaped as:
327        <pre class="html example">
328    <code>&amp;lt;/</code></pre>
329        </p>
330      </div>
331    
332    <div class="section" id="bare-stago"><h3>A <code>&lt;</code> character is not followed
333      by tag name or by a <code>!</code> character.</h3>
334        <p>A <code>&lt;</code> (<code>U+003C</code>
335        <code class="charname">LESS-THAN SIGN</code>) character which is not part
336        of any markup appears in the input stream.</p>
337    
338        <p>The <code>&lt;</code> character as a data character must
339        be escaped as:
340        <pre class="html example">
341    <code>&amp;lt;</code></pre>
342        </p>
343      </div>
344    
345    <div class="section" id="bare-nero"><h3>The decimal representation of the code position
346    of a character must be specified after <code>&amp;#</code>.</h3>    of a character must be specified after <code>&amp;#</code>.</h3>
347      <p>An <code>&amp;</code> (<code>U+0026</code>      <p>An <code>&amp;</code> (<code>U+0026</code>
348      <code class="charname">AMPERSAND</code>) character immediately      <code class="charname">AMPERSAND</code>) character immediately
# Line 66  Web Document Conformance Checker (BETA)< Line 352  Web Document Conformance Checker (BETA)<
352      The document is non-conforming.</p>      The document is non-conforming.</p>
353    
354      <p>The string <code>&amp;#</code> must be the first two characters      <p>The string <code>&amp;#</code> must be the first two characters
     <code>NUMBER SIGN</code>) character must be the first two characters  
355      of a reference:      of a reference:
356        <dl>        <dl class="switch">
357        <dt>Numeric character reference</dt>        <dt>Numeric character reference</dt>
358            <dd><pre class="html example">            <dd><pre class="html example">
359  <code>&amp;#<var>d</var>;</code></pre>  <code>&amp;#<var>d</var>;</code></pre>
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368      </p>      </p>
369    
370      <p>To represent <code>&amp;#</code> as data characters, use      <p>To represent <code>&amp;#</code> as data characters, use
371      named entity reference:      a named entity reference for the <code>&amp;</code> character:
372        <pre class="html example">        <pre class="html example">
373  <code>&amp;amp;#</code></pre>  <code>&amp;amp;#</code></pre>
374      </p>      </p>
375    </div>    </div>
376    
377  <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
378    of a character must be specified after <code>&amp;#x</code>.</h3>    of a character must be specified after <code>&amp;#x</code>.</h3>
379     <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
380     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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388      of the code point of the character to be referenced.</p>      of the code point of the character to be referenced.</p>
389    
390      <p>To represent <code>&amp;#x</code> as data characters, use      <p>To represent <code>&amp;#x</code> as data characters, use
391      named entity reference:      a named entity reference for the <code>&amp;</code> character:
392        <pre class="html example">        <pre class="html example">
393  <code>&amp;amp;#x</code></pre>  <code>&amp;amp;#x</code></pre>
394      </p>      </p>
395    </div>    </div>
396    
397  <div class="section tokenize-error" id="duplicate-attribute"><h3>There are two attributes with same name.</h3>  <div class="section" id="bogus-comment"><h3>String <code>&lt;!</code> is not followed
398      by <code>--</code>.</h3>
399        <p>There is a <code>&lt;</code> (<code>U+003C</code>
400        <code class="charname">LESS-THAN SIGN</code>) character
401        followed by a <code>!</code> (<code>U+0021</code>
402        <code class="charname">EXCLAMATION MARK</code>) character,
403        which is not followed by a <code>--</code> or
404        <code>!DOCTYPE</code>.  The document is non-conforming.</p>
405    
406        <dl class="switch">
407        <dt>Comments</dt>
408          <dd>In HTML document, comments must be introduced by
409          <code class="example">&lt;!--</code> (<code>&lt;!</code>
410          <em>immediately</em> followed
411          by <em>two</em> <code>-</code>s) and must be terminated by
412          <code class="example">--&gt;</code>.
413          Strings <code>&lt;!</code> not followed
414          by <code>--</code> and <code>&lt;!-</code> not followed by
415          <code>-</code> are not valid open delimiters for comments.</dd>
416        <dt>Marked sections, including <code>CDATA</code> sections</dt>
417          <dd>Marked sections are not allowed in HTML document.</dd>
418        <dt>Markup declarations</dt>
419          <dd>Markup declarations, except for <code>DOCTYPE</code>
420          and comment declarations, are not allowed in HTML document.</dd>
421        <dt>String <code>&lt;!</code></dt>
422          <dd>String <code>&lt;!</code> must be escaped as
423          <code class="example">&amp;lt;!</code>.</dd>
424        </dl>
425      </div>
426    
427    <div class="section" id="bogus-end-tag"><h3>String <code>&lt;/</code> is not followed
428      by tag name.</h3>
429        <p>There is a <code>&lt;</code> (<code>U+003C</code>
430        <code class="charname">LESS-THAN SIGN</code>) character
431        immediately followed by a <code>/</code> (<code>U+005F</code>
432        <code>SOLIDUS</code>) character, which is not part
433        of any end tag, in the input stream.  The document
434        is non-conforming.</p>
435    
436        <p>The <code>&lt;/</code> sequence not followed by a
437        tag name is parsed as an opening of bogus comment.</p>
438    
439        <p>The <code>&lt;/</code> sequence as string data must
440        be escaped as:
441        <pre class="html example">
442    <code>&amp;lt;/</code></pre>
443        </p>
444      </div>
445    
446    <div class="section" id="dash-in-comment"><h3>There is a <code>--</code> sequence
447      in a comment.</h3>
448        <p>There is a <code>-</code> (<code>U+002D</code>
449        <code class="charname">HYPHEN-MINUS</code>) character
450        at the end of the comment or a <code>--</code> sequence
451        in the comment.  The document is non-conforming.</p>
452    
453        <p>Comments cannot contain a string <code>--</code>, as in XML.
454        Unlike SGML, there cannot be more than one comments
455        (where <i>comment</i> is an SGML term) in the comment
456        declaration.</p>
457      </div>
458    
459    <div class="section" id="duplicate-attribute"><h3>There are two attributes with name
460          <code><var>{text}</var></code>.</h3>
461      <p>There are more than one attributes with the same      <p>There are more than one attributes with the same
462      name in a tag.  The document is non-conforming.</p>      name in a tag.  The document is non-conforming.</p>
463    
# Line 117  Web Document Conformance Checker (BETA)< Line 465  Web Document Conformance Checker (BETA)<
465      Use <code>img</code> element with animation GIF instead.</p>      Use <code>img</code> element with animation GIF instead.</p>
466    </div>    </div>
467    
468  <div class="section tokenize-error" id="nestc"><h3>Void element syntax (<code>/&gt;</code>) cannot be  <div class="section" id="empty-start-tag"><h3>Empty start tag (<code>&lt;&gt;</code>) is not
469      allowed.</h3></div>
470    
471    <div class="section" id="empty-end-tag"><h3>Empty end tag (<code>&lt;/&gt;</code>) is not
472      allowed.</h3></div>
473    
474    <div class="section" id="end-tag-attribute"><h3>End tag cannot have attributes.</h3></div>
475    
476    <div class="section" id="empty-unquoted-attribute-value"><h3>Attribute value is not specified.</h3>
477        <p>The attribute value is not specified after the <code>=</code>
478        (<code>U+003C</code> <code class="charname">EQUAL SIGN</code>)
479        character.</p>
480    
481        <p>When an attribute value is empty, the <code>=</code> character after
482        the attribute name must be specified as:</p>
483    
484        <p><code class="html example">&lt;foo bar&gt;</code></p>
485    
486        <p>Instead, quotation marks can be used to explicitly represent that
487        the attribute value is empty, as:</p>
488    
489        <p><code class="html example">&lt;foo bar=""&gt;</code></p>
490    
491        <p>... or like:</p>
492    
493        <p><code class="html example">&lt;foo bar=''&gt;</code></p>
494      </div>
495    
496    <div class="section" id="invalid-character-reference"><h3>Character reference to
497      <code><var>{text}</var></code> is not allowed.</h3></div>
498    
499    <div class="section" id="nestc"><h3>Polytheistic slash (<code>/&gt;</code>) cannot be
500    used for this element.</h3>    used for this element.</h3>
501      <p>Void element syntax (<code>/&gt;</code>) must not be used      <p>Polytheistic slash (<code>/&gt;</code>) must not be used
502      for the element.  The document is non-conforming.</p>      for the element.  The document is non-conforming.</p>
503    
504      <p>The void element syntax can only be      <p>The polytheistic slash can only be
505      used for <code>base</code>, <code>link</code>, <code>meta</code>,      used for <code>base</code>, <code>link</code>, <code>meta</code>,
506      <code>hr</code>, <code>br</code>, <code>img</code>,      <code>hr</code>, <code>br</code>, <code>img</code>,
507      <code>embed</code>, <code>param</code>, <code>area</code>,      <code>embed</code>, <code>param</code>, <code>area</code>,
508      <code>col</code>, and <code>input</code> elements.</p>      <code>col</code>, and <code>input</code> elements.</p>
509    
510      <p>Note that, unlike in XML, the void element syntax has      <dl class="switch">
511        <dt><code>&lt;script/&gt;</code></dt>
512            <dd><p>The polytheistic slash cannot be used for <code>script</code>
513            element.  Even for an empty <code>script</code> element,
514            there must be an explicit end tag
515            <code class="html example">&lt;/script&gt;</code>.</p>
516    
517            <p><strong>NOTE</strong>: Though some user agents interpret
518            polytheistic slash for <code>script</code> element as the
519            closing of the element, such usage is not allowed under
520            the current standard.</p></dd>
521        <dt><code>&lt;basefont/&gt;</code>, <code>&lt;bgsound/&gt;</code>,
522        <code>&lt;frame/&gt;</code>, <code>&lt;keygen/&gt;</code>,
523        <code>&lt;spacer/&gt;</code>, <code>&lt;wbr/&gt;</code></dt>
524            <dd>These elements are themselves non-conforming.</dd>
525        <!-- isindex, image -->
526        <dt><code>&lt;command/&gt;</code>, <code>&lt;event-source/&gt;</code>,
527        <code>&lt;nest/&gt;</code>, or <code>&lt;source/&gt;</code></dt>
528            <dd>Future revision of HTML5 parsing algorithm is expected
529            to allow polytheistic slash for these elements.</dd>
530        <dt><code>&lt;a/&gt;</code>, <code>&lt;p/&gt;</code></dt>
531            <dd>These elements are not always empty and therefore
532            polytheistic slash is not allowed.  Use explicit end tag
533            to represent empty element as:
534              <pre class="example html">
535    <code>&lt;p&gt;&lt;/p&gt;</code></pre>
536            </dd>
537        </dl>
538    
539        <p>Note that, unlike in XML, the polytheistic slash has
540      no effect in HTML.</p>      no effect in HTML.</p>
541    </div>    </div>
542    
543    <div class="section" id="no-DOCTYPE-name"><h3>After the string <code>&lt;!DOCTYPE </code>, the
544      document type name must be specified.</h3></div>
545    
546    <div class="section" id="no-PUBLIC-literal"><h3>After the keyword <code>PUBLIC</code>, no
547      oublic identifier is specified.</h3></div>
548    
549    <div class="section" id="no-refc"><h3>Character reference must be closed by a
550      <code>;</code> character.</h3></div>
551    
552    <div class="section" id="no-space-before-DOCTYPE-name"><h3>After the string <code>&lt;!DOCTYPE</code>, there
553      must be at least a white space character before the document type
554      name.</h3></div>
555    
556    <div class="section" id="no-space-between-attributes"><h3>Attributes must be separeted by at least a
557      white space character.</h3></div>
558    
559    <div class="section" id="no-SYSTEM-literal"><h3>After the keyword <code>SYSTEM</code>, no
560      system identifier is specified.</h3></div>
561    
562    <div class="section" id="pio"><h3>Processing instruction
563      (<code>&lt;?<var>...</var>&gt;</code>) is not allowed in HTML
564      document.</h3>
565        <p>Processing instructions (<code>&lt;?<var>...</var>?&gt;</code>),
566        including XML declaration (<code>&lt;?xml <var>...</var>?&gt;</code>)
567        and XML style sheet <abbr title="processing instruction">PI</abbr>
568        (<code>&lt;?xml-stylesheet <var>...</var>?&gt;</code>), are not allowed
569        in the HTML syntax.  The document is non-conforming.</p>
570    
571        <dl class="switch">
572        <dt><code>&lt;?xbl?&gt;</code> (<abbr>XBL</abbr> Association)</dt>
573          <dd>An <abbr>XBL</abbr> binding cannot be associated by
574          <abbr title="processing instruction">PI</abbr> in <abbr>HTML</abbr>
575          document.  Use <code>binding</code> property in <abbr>CSS</abbr>
576          style sheet as:
577            <pre class="html example">
578    <code>&lt;style&gt;
579    p {
580      binding: url(binding.xbl);
581    }
582    &lt;/style&gt;</code></pre>
583          </dd>
584        <dt><code>&lt;?xml?&gt;</code> (XML declaration)</dt>
585            <dd>XML declaration is unnecessary for HTML documents.</dd>
586        <dt><code>&lt;?xml-stylesheet?&gt;</code> (XML style sheet
587        <abbr title="processing instruction">PI</abbr>)</dt>
588            <dd>Use HTML <code>link</code> element with <code>rel</code>
589            attribute set to <code>stylesheet</code> (or,
590            <code>alternate stylesheet</code> for an alternate style
591            sheet).
592              <pre class="example html">
593    <code>&lt;link rel=stylesheet href="path/to/stylesheet.css"&gt;</code></pre>
594            </dd>
595        <dt><code>&lt;?php?&gt;</code> or
596        <code>&lt;? <var>... <abbr>PHP</abbr> code ...</var> ?&gt;</code>
597        (<abbr>PHP</abbr> code)</dt>
598            <dd>The conformance checker does <em>not</em> support
599            checking for PHP source documents.</dd>
600        <dt>Other processing instructions</dt>
601            <dd>Processing instructions cannot be inserted in an HTML
602            document.  Use XML document or insert
603            <code>ProcessingInstruction</code> node by scripting.</dd>
604        </dl>
605    
606        <p>Web browsers will parse processing instructions as bogus
607        comments.  Some legacy Web browsers, such as IE:mac and
608        some mobile Web browsers, will display processing instructions
609        as string.</p>
610      </div>
611    
612    <div class="section" id="string-after-DOCTYPE-name"><h3>There is a bogus string after the document type
613      name.</h3></div>
614    
615    <div class="section" id="string-after-PUBLIC"><h3>There is a bogus string after the keyword
616      <code>PUBLIC</code>.</h3></div>
617    
618    <div class="section" id="string-after-PUBLIC-literal"><h3>There is a bogus string after the public
619      identifier.</h3></div>
620    
621    <div class="section" id="string-after-SYSTEM"><h3>There is a bogus string after the keyword
622      <code>SYSTEM</code>.</h3></div>
623    
624    <div class="section" id="string-after-SYSTEM-literal"><h3>There is a bogus string after the system
625      identifier.</h3></div>
626    
627    <div class="section" id="unclosed-attribute-value"><h3>Attribute value is not closed by a quotation
628      mark.</h3></div>
629    
630    <div class="section" id="unclosed-comment"><h3>Comment is not closed by a string
631      <code>--&gt;</code>.</h3></div>
632    
633    <div class="section" id="unclosed-DOCTYPE"><h3>The <code>DOCTYPE</code> is not closed by a
634      <code>&gt;</code> character.</h3></div>
635    
636    <div class="section" id="unclosed-PUBLIC-literal"><h3>The public identifier literal is not closed by a
637      quotation mark.</h3></div>
638    
639    <div class="section" id="unclosed-SYSTEM-literal"><h3>The system identifier literal is not closed by a
640      quotation mark.</h3></div>
641    
642    <div class="section" id="unclosed-tag"><h3>Tag is not closed by a <code>&gt;</code>
643      character.</h3></div>
644    
645  </section>  </section>
646    
647  <section id="html5-parse-errors">  <section id="html5-parse-errors">
648  <h2>HTML5 Parse Errors in Tree Construction Stage</h2>  <h2>HTML5 Parse Errors in Tree Construction Stage</h2>
649    
650  <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
651    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
652      is closed.</h3></div>
653    
654    <div class="section" id="after-after-frameset:/"><h3>There is an end tag
655      <code>&lt;/<var>{text}</var>&gt;</code> is after the <code>html</code> element
656      is closed.</h3></div>
657    
658    <div class="section" id="after-body"><h3>Start tag <code>&lt;<var>{text}</var>&gt;</code> is
659      not allowed after the <code>body</code> is closed.</h3></div>
660    
661    <div class="section" id="after-body:/"><h3>End tag <code>&lt;/<var>{text}</var>&gt;</code> is
662      not allowed after the <code>body</code> is closed.</h3></div>
663    
664    <div class="section" id="after-body:#text"><h3>Non‐white‐space characters are not allowed
665      after the <code>body</code> is closed.</h3></div>
666    
667    <div class="section" id="after-frameset"><h3>Start tag <code>&lt;<var>{text}</var>&gt;</code> is
668      not allowed after the <code>frameset</code> is closed.</h3></div>
669    
670    <div class="section" id="after-frameset:/"><h3>End tag <code>&lt;/<var>{text}</var>&gt;</code> is
671      not allowed after the <code>frameset</code> is closed.</h3></div>
672    
673    <div class="section" id="after-frameset:#text"><h3>Non‐white‐space characters are not allowed
674      after the <code>frame</code> is closed.</h3></div>
675    
676    <div class="section" id="after-head"><h3>The <code><var>{text}</var></code> element cannot be
677      inserted between <code>head</code> and <code>body</code>
678      elements.</h3>
679      <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
680      but before the <code>body</code> element is opened.      but before the <code>body</code> element is opened.
681      The document is non-conforming.</p>      The document is non-conforming.</p>
682    </div>    </div>
683    
684  <div class="section parse-error" id="in-table"><h3>Tag <code>&lt;<var>$0</var>&gt;</code>  <div class="section" id="after-html"><h3>Start tag <code>&lt;<var>{text}</var>&gt;</code> is
685    is not allowed in <code>table</code>.</h3>    not allowed after the <code>html</code> is closed.</h3>
686      <p>The start or end tag of an element appears in <code>table</code>.      <p>The start tag of an element appears after the
687        <code>body</code> element has been closed.  The document is
688        non-conforming.</p>
689    
690        <p>Any content of the document other than <code>head</code>
691        contents and comments must be put into the <code>body</code>
692        element.</p>
693      </div>
694    
695    <div class="section" id="after-html:/"><h3>End tag <code>&lt;/<var>{text}</var>&gt;</code> is
696      not allowed after the <code>html</code> is closed.</h3>
697        <p>The end tag of an element appears after the
698        <code>body</code> element has been closed.  The document is
699        non-conforming.</p>
700    
701        <p>Any content of the document other than <code>head</code>
702        contents and comments must be put into the <code>body</code>
703        element.</p>
704      </div>
705    
706    <div class="section" id="after-html:#text"><h3>Non‐white‐space characters are not allowed
707      after the <code>html</code> is closed.</h3></div>
708    
709    <div class="section" id="image"><h3>The <code>image</code> element is
710      obsolete.</h3></div>
711    
712    <div class="section" id="in-a:a"><h3>Anchor cannot be nested.</h3>
713        <p>HTML <code>a</code> elements cannot be nested.
714        The document is non-conforming.</p>
715    
716        <p>In the HTML syntax, a start tag of the <code>a</code>
717        implies the end tag of any opening <code>a</code> element.</p>
718      </div>
719    
720    <div class="section" id="in-body"><h3>Start tag <code>&lt;<var>{text}</var>&gt;</code>
721      is not allowed in the <code>body</code> element.</h3>
722        <p>The start or end tag of an element, which
723        cannot be a descendant of <code>body</code> element, appears
724        in the input stream while the <code>body</code> element has been opened.
725      The document is non-conforming.</p>      The document is non-conforming.</p>
726      </div>
727    
728    <div class="section" id="in-body:#eof"><h3>Some element is not closed before the end of
729      file.</h3></div>
730    
731    <div class="section" id="in-button:button"><h3>The <code>button</code> element cannot be
732      nested.</h3></div>
733    
734    <div class="section" id="in-CDATA:#eof"><h3>Element is not closed before the end of
735      file.</h3></div>
736    
737    <div class="section" id="in-form:form"><h3>Start tag <code>&lt;form&gt;</code> is
738      not allowed in a <code>form</code> element.</h3></div>
739    
740    <div class="section" id="in-frameset"><h3>Start tag <code>&lt;<var>{text}</var>&gt;</code> is
741      not allowed in a <code>framset</code> element.</h3></div>
742    
743    <div class="section" id="in-frameset:/"><h3>End tag <code>&lt;/<var>{text}</var>&gt;</code> is
744      not allowed in a <code>frameset</code> element.</h3></div>
745    
746    <div class="section" id="in-frameset:#text"><h3>Non‐white‐space characters are not allowed
747      in a <code>frameset</code> element.</h3></div>
748    
749    <div class="section" id="in-head:head"><h3>Start tag <code>&lt;head&gt;</code>
750      is not allowed in the <code>head</code> element.</h3>
751        <p>There is a start tag <code>&lt;head&gt;</code> in the
752        <code>&lt;head&gt;</code> element.  The document is non-conforming.</p>
753    
754        <p>In an HTML document there must not be more than
755        one <code>head</code> element, therefore no more than one
756        start tag <code>&lt;head&gt;</code> can appear in the input stream.</p>
757      </div>
758    
759    <div class="section" id="in-html:#DOCTYPE"><h3>A <code>DOCTYPE</code> appears after any
760      element or data character has been seen.</h3>
761        <p>A <code>DOCTYPE</code> appears after any element or data character
762        has been seen.  The document is non-conforming.</p>
763        
764        <p>The <code>DOCTYPE</code> must be placed before any
765        tag, reference, or data character.  Only white space characters
766        and comments can be inserted before the <code>DOCTYPE</code>.</p>
767      </div>
768    
769    <div class="section" id="in-nobr:nobr"><h3>The <code>nobr</code> element cannot be
770      nested.</h3></div>
771    
772    <div class="section" id="in-noscript"><h3>The <code><var>{text}</var></code> element is not
773      allowed in a <code>noscript</code> element in the
774      <code>head</code> element.</h3></div>
775    
776    <div class="section" id="in-noscript:/"><h3>An end tag <code>&lt;/<var>{text}</var>&gt;</code>
777      appers before the <code>noscript</code> element is closed.</h3></div>
778    
779    <div class="section" id="in-noscript:#eof"><h3>A <code>noscript</code> element is not closed
780      before the end of file.</h3></div>
781    
782    <div class="section" id="in-noscript:#text"><h3>Non‐white‐space characters are not allowed
783      in a <code>noscript</code> element in the <code>head</code>
784      element.</h3></div>
785    
786    <div class="section" id="in-PCDATA:#eof"><h3>Element is not closed before the end of
787      file.</h3></div>
788    
789    <div class="section" id="in-select"><h3>Start tag <code>&lt;<var>{text}</var>&gt;</code>
790      is not allowed in a <code>select</code> element.</h3></div>
791    
792    <div class="section" id="in-select:/"><h3>End tag <code>&lt;/<var>{text}</var>&gt;</code>
793      is not allowed in a <code>select</code> element.</h3></div>
794    
795    <div class="section" id="in-table"><h3>Start tag <code>&lt;<var>{text}</var>&gt;</code>
796      is not allowed in a <code>table</code> element.</h3>
797        <p>The start or end tag of an element, which
798        cannot be a child of <code>table</code> element, appears
799        in the input stream while the <code>table</code> element has been opened
800        but no other element has been opened.  The document is non-conforming.</p>
801    
802      <p>In <code>table</code>, only table related elements      <p>In <code>table</code>, only table related elements
803      are allowed; any other element must be contained in      are allowed; any other element must be contained in
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806      a table caption.</p>      a table caption.</p>
807    </div>    </div>
808    
809  <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>
810    <code>table</code>.</h3>    is not allowed in a <code>table</code> element.</h3></div>
811      <p>A data character appears in <code>table</code>.  The document  
812      is non-conforming.</p>  <div class="section" id="in-table:#text"><h3>Non‐white‐space character is not allowed within
813      the <code>table</code> element, outside of the caption and cells.</h3>
814        <p>A non‐white‐space character appears in <code>table</code>.
815        The document is non-conforming.</p>
816    
817      <p>In <code>table</code>, only table related elements      <p>In <code>table</code>, only table related elements
818      are allowed; any other element and data character must be contained in      are allowed; any other element and data character must be contained in
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821      a table caption.</p>      a table caption.</p>
822    </div>    </div>
823    
824  <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
825      obsolete.</h3></div>
826    
827    <div class="section" id="missing-start-tag:tr"><h3>Start tag of <code>tr</code>
828    element is missing.</h3>    element is missing.</h3>
829      <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>
830      optional, is missing.  The document is non-conforming.</p>      optional, is missing.  The document is non-conforming.</p>
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836      these start tags, it must be explicitly specified.</p>      these start tags, it must be explicitly specified.</p>
837    </div>    </div>
838    
839  <div class="section parse-error" id="no-DOCTYPE"><h3>This document does not start with the  <div class="section" id="no-DOCTYPE"><h3>This document does not start with a
840    <code>DOCTYPE</code>.</h3>    <code>DOCTYPE</code>.</h3>
841      <p>The document does not start with a <code>DOCTYPE</code>.      <p>The document does not start with a <code>DOCTYPE</code>.
842      The document is non-conforming.</p>      The document is non-conforming.</p>
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847      </p>      </p>
848    
849      <p>Only white space characters and comments are allowed      <p>Only white space characters and comments are allowed
850      before the <code>DOCTYPE</code>.</p>      before the <code>DOCTYPE</code>.  XML declaration is <em>not</em>
851        allowed in HTML document.</p>
852    </div>    </div>
853    
854  <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
855    closed.</h3>    closed.</h3>
856      <p>End tag of an element is not found before, for example,      <p>End tag of an element is not found before, for example,
857      an end tag of another element appears or      an end tag of another element appears or
858      the end of the document.  The document is non-conforming.</p>      the end of the document.  The document is non-conforming.</p>
859    
860        <p>Only <code>body</code>, <code>colgroup</code>, <code>dd</code>,
861        <code>dt</code>, <code>head</code>, <code>html</code>, <code>li</code>,
862        <code>ol</code>, <code>option</code>, <code>optgroup</code>,
863        <code>p</code>, <code>rb</code>, <code>rp</code>, <code>rt</code>,
864        <code>tbody</code>, <code>td</code>, <code>tfoot</code>,
865        <code>th</code>, <code>thead</code>, <code>tr</code>,
866        <code>ul</code> end tag can be omitted in HTML documents.
867        For any element except for void element, there must be an explicit
868        end tag.</p>
869    
870        <dl class="switch">
871        <dt>HTML <code>canvas</code> element</dt>
872          <dd>Though the element is void in earlier versions of Safari,
873          the <code>canvas</code> element is <em>no</em> longer
874          defined as empty.  There must be an end tag
875          <code class="html example">&lt;/canvas&gt;</code>.</dd>
876        </dl>
877    
878        <p>Note that misnesting tags, such as
879        <code class="bad example">&lt;a&gt;&lt;b&gt;&lt;/a&gt;&lt;/b&gt;</code>, are not
880        allowed and they also cause this error.</p>
881      </div>
882    
883    <div class="section" id="not-first-start-tag"><h3>This <code>&lt;html&gt;</code> tag is not
884      the first start tag.</h3>
885        <p>There is a start tag of the <code>html</code> element
886        that it not the first start tag in the input stream.
887        The document is non-conforming.</p>
888    
889        <p>In an HTML document, there cannot be more than one
890        <code>html</code> element and therefore there cannot be
891        more than one <code>&lt;html&gt;</code> tag.  In addition,
892        nothing can be placed before the <code>&lt;html&gt;</code> tag
893        except a <code>DOCTYPE</code>, white space characters,
894        and comments.</p>
895    </div>    </div>
896    
897  <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
898    HTML.</h3>    HTML.</h3>
899      <p>The document contains a <code>DOCTYPE</code> declaration      <p>The document contains a <code>DOCTYPE</code> declaration
900      that is different from HTML5 <code>DOCTYPE</code> (i.e. <code>&lt;!DOCTYPE      that is different from HTML5 <code>DOCTYPE</code> (i.e.
901      HTML&gt;</code>).  The document is non-conforming.</p>      <code class="example html">&lt;!DOCTYPE HTML&gt;</code>).
902        The document is non‐conforming.</p>
903    
904      <p>The document might or might not be conformant to      <p>The document might or might not be conformant to
905      some version of HTML.  However, conformance to any HTML      some version of HTML.  However, conformance to any HTML
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908      HTML document (roughly) as defined in HTML5.</p>      HTML document (roughly) as defined in HTML5.</p>
909    </div>    </div>
910    
911  <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
912    opened.</h3></div>    not allowed here.</h3></div>
913    
914    <div class="section" id="unmatched-end-tag"><h3>Element <code><var>{text}</var></code> is not
915      opened.</h3>
916        <p>An end tag appears though no element with the same name
917        has been opened.  The document is non-conforming.</p>
918    
919        <p>For any end tag in HTML document, there must be a
920        corresponding start tag.</p>
921    
922        <dl class="switch">
923        <dt>HTML <code>base</code>, <code>basefont</code>,
924        <code>bgsound</code>, <code>br</code>, <code>col</code>,
925        <code>embed</code>, <code>frame</code>, <code>hr</code>,
926        <code>image</code>, <code>img</code>, <code>input</code>,
927        <code>isindex</code>, <code>link</code>, <code>meta</code>,
928        <code>param</code>, <code>spacer</code>, or <code>wbr</code> element</dt>
929          <dd>End tag is not allowed for these elements, since
930          those content must always be empty.  Remove end tag.</dd>
931        <!-- keygen -->
932        <!-- command, event-source, nest, source -->
933        </dl>
934      </div>
935    
936    <div class="section" id="XSLT-compat"><h3>The <code>DOCTYPE</code> legacy string is
937      used.</h3>
938        <p>The <code>DOCTYPE</code> with the <code>DOCTYPE</code> legacy
939        string, i.e.
940        <code class="html bad example">&lt;!DOCTYPE HTML PUBLIC "XSLT-compat"&gt;</code>
941        is used.</p>
942    
943        <p>The <code>DOCTYPE</code> legacy string should not be used for documents
944        <em>not</em> generated from XSLT transformation process.  It is allowed
945        only to enable to use XSLT style sheets with the HTML output mode, which
946        does not support generation of the <code>DOCTYPE</code> with no
947        <code>PUBLIC</code>
948        identifier.  For other purposes, the <code>DOCTYPE</code> legacy
949        string, i.e. <code class="html bad example">PUBLIC "XSLT-compat"</code>,
950        is useless and should not be used.</p>
951      </div>
952    
953  </section>  </section>
954    
955  <section id="element-content-model-errors">  <section id="element-content-model-errors">
956  <h2>Element Content Model Errors</h2>  <h2>Element Content Model Errors</h2>
957    
958  <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
959      <code>href</code> attribute specified cannot be placed after
960      any attribute with a URL.</h3></div>
961    
962    <div class="section" id="basetarget-after-hyperlink"><h3>The <code>base</code> element with the
963      <code>target</code> attribute specified cannot be placed after
964      any element that defines a hyperlink.</h3></div>
965    
966    <div class="section" id="character-not-allowed"><h3>Data character is not allowed in this
967    context.</h3>    context.</h3>
968      <p>A data character appears where it is not allowed in this      <p>A data character appears where it is not allowed in this
969      context.  The document is non-conforming.</p>      context.  The document is non-conforming.</p>
970    
971      <p>Possible causes:      <p>Possible causes:
972        <dl>        <ul>
973        <dt>If the erred element is an inline-level element (such        <li><p>A data character cannot be a child
974        as <code>a</code> or <code>span</code>)</dt>        of certain sectioning elements such as <code>body</code>,
975            <dd><p>A data character cannot be a child        <code>section</code>, and <code>blockquote</code>.</p>
976            of certain sectioning elements such as <code>body</code>,  
977            <code>section</code>, and <code>blockquote</code>.</p>        <p>Any inline-level content must be put
978          in e.g. paragraph element such as <code>p</code>.</p></li>
979            <p>Any inline-level content must be put        <li><p>Though some elements such as <code>div</code>,
980            in e.g. paragraph element such as <code>p</code>.</p></dd>        <code>li</code>, and <code>td</code> allow
981        <dt>If the erred element is a block-level element (such as        <em>either one</em> of block-level or inline-level content
982        <code>div</code> or <code>h<var>n</var></code>)</dt>        is allowed.  If there is a block-level content,
983            <dd><p>Though some elements such as <code>div</code>,        any inline-level content must be put
984            <code>li</code>, and <code>td</code> allow        in e.g. paragraph element such as <code>p</code>.</p></li>
985            <em>either one</em> of block-level or inline-level content        </ul>
           is allowed.  If there is a block-level content,  
           any inline-level content must be put  
           in e.g. paragraph element such as <code>p</code>.</p></dd>  
       </dl>  
986      </p>      </p>
987    </div>    </div>
988    
989  <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
990    element as a child of this element.</h3>    an empty element.</h3></div>
991    
992    <div class="section" id="character-not-allowed:atom|PersonConstruct"><h3>Non‐white‐space characters are not allowed in
993      Person construct.</h3></div>
994    
995    <div class="section" id="character-not-allowed:atom|TextConstruct"><h3>Non‐white‐space characters are not allowed in
996      Text construct.</h3></div>
997    
998    <div class="section" id="child-element-missing"><h3>There must be an element
999      <code><var>{text}</var></code> as a child of this element.</h3>
1000      <p>The content model of the element is so defined that it      <p>The content model of the element is so defined that it
1001      must contain a <code><var>$0</var></code> child element.      must contain a <code><var>$0</var></code> child element.
1002      The document is non-conforming.</p>      The document is non-conforming.</p>
1003    
1004      <p>For example:      <dl class="switch">
1005        <ul>      <dt>HTML <code>head</code> element</dt>
1006        <li>The <code>head</code> element must contain exactly one        <dd>There must be a <code>title</code> child element.</dd>
1007        <code>title</code> child element.</li>      <dt>HTML <code>html</code> element</dt>
1008        <li><a href="#child-element-missing:td%7Cth">The <code>tr</code>        <dd>There must be a <code>head</code> child element followed
1009        element must contain one or more <code>td</code> or <code>th</code>        by a <code>body</code> element.</dd>
1010        child element.</a></li>      <dt>HTML <code>tr</code> element</dt>
1011        </ul>        <dd><a href="#child-element-missing:td%7Cth">There must be
1012      </p>        one or more <code>td</code> or <code>th</code> child element.</a></dd>
1013        </dl>
1014    </div>    </div>
1015    
1016  <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>
1017    or <code>th</code> element as a child of this element.</h3>    or <code>th</code> element as a child of this element.</h3>
1018      <p>The <code>tr</code> element must contain at least one      <p>The <code>tr</code> element must contain at least one
1019      <code>td</code> or <code>th</code> child element.  The document      <code>td</code> or <code>th</code> child element.  The document
1020      is non-conforming.</p>      is non-conforming.</p>
1021    </div>    </div>
1022    
1023  <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
1024      <code><var>{text}</var></code> in the Atom namespace as a child of this
1025      element.</h3></div>
1026    
1027    <div class="section" id="child-element-missing:atom:link:alternate"><h3>There must be an Atom <code>link</code> element
1028      whose <code>rel</code> attribute is set to <code>alternate</code> as a
1029      child of this element.</h3></div>
1030    
1031    <div class="section" id="child-element-missing:atom:link:self"><h3>There should be an Atom <code>link</code> element
1032      whose <code>rel</code> attribute is set to <code>self</code> as a
1033      child of this element.</h3></div>
1034    
1035    <div class="section" id="element-missing:hn"><h3>There must be at least one
1036      <code>h<var>n</var></code> element descendant.</h3></div>
1037    
1038    <div class="section" id="element-not-allowed"><h3>This element is not allowed in this
1039    context.</h3>    context.</h3>
1040      <p>An element appears where it is not allowed.  The document      <p>An element appears where it is not allowed.  The document
1041      is non-conforming.</p>      is non-conforming.</p>
1042    
     <p><strong>Note</strong>: The conformance checker does  
     <em>not</em> support form elements yet.</p>  
   
1043      <p>Possible causes:      <p>Possible causes:
1044        <dl>        <dl class="switch">
1045        <dt>If the erred element is an inline-level element (such        <dt>If the element with the error is an inline-level element,
1046        as <code>a</code> or <code>span</code>)</dt>        such as <code>a</code>, <code>progress</code>, or <code>img</code></dt>
1047            <dd><p>An inline-level element cannot be a child            <dd><p>An inline-level element cannot be a child
1048            of certain sectioning elements such as <code>body</code>,            of certain sectioning elements such as <code>body</code>,
1049            <code>section</code>, and <code>blockquote</code>.</p>            <code>section</code>, and <code>blockquote</code>.</p>
1050    
1051            <p>Any inline-level content must be put            <p>Any inline-level content must be put
1052            in e.g. paragraph element such as <code>p</code>.</p></dd>            in e.g. paragraph element such as <code>p</code>.</p></dd>
1053        <dt>If the erred element is a block-level element (such as        <dt>If it is a block-level elements, such as <code>aside</code>,
1054        <code>div</code> or <code>h<var>n</var></code>)</dt>        <code>div</code>, <code>h<var>n</var></code>,
1055            <dd><p>Though some elements such as <code>div</code>,        <code>p</code>, or <code>section</code></dt>
1056            <code>li</code>, and <code>td</code> allow            <dd><dl class="switch">
1057            <em>either one</em> of block-level or inline-level content                <dt>If the parent element is <code>div</code>,
1058            is allowed.  If there is a block-level content,                <code>li</code>, <code>td</code>, or <code>th</code></dt>
1059            any inline-level content must be put                <!-- @@ TODO: more... -->
1060            in e.g. paragraph element such as <code>p</code>.</p></dd>                    <!-- @@ TODO: <p><ul><li><p> -->
1061        <dt>If the erred element is the root <code>html</code> element</dt>                    <dd><p>The parent element allows <em>either</em>
1062            <dd><p>In an XHTML document, the root <code>html</code>                    block-level or inline-level content.  If there is a
1063            element must have an <code>xmlns</code> attribute                    block-level content, any inline-level content must be
1064            whose value is set to                    put in e.g. paragraph element such as <code>p</code>.</p>
1065            <code>http://www.w3.org/1999/xhtml</code>.</p></dd>                    <p>For example, an HTML document fragment
1066                      <code class="html bad example">&lt;div&gt;&lt;p&gt;Hello!&lt;/p&gt; World!&lt;/div&gt;</code>
1067                      is non-conforming, since a word <q>World!</q> does not belong
1068                      to any paragraph.  (If not part of any paragraph, what is
1069                      it!?)  A conforming example would be:
1070                        <pre class="html example">
1071    <code>&lt;div&gt;&lt;p&gt;Hello!&lt;/p&gt; &lt;p&gt;World!&lt;/p&gt;&lt;/div&gt;</code></pre>
1072                      </p></dd>
1073                  <dt>If the parent element does <em>not</em> allow
1074                  block-level elements as content</dt>
1075                      <dd>The element is not allowed to be inserted here.
1076                      For example, a <code>div</code> element cannot be
1077                      a child of an <code>h1</code> element.</dd>
1078              </dl></dd>
1079          <dt>If the element with the error is a <code>noscript</code> element</dt>
1080              <dd>The <code>noscript</code> element is allowed only in the context
1081              where a block-level or inline-level content is expected
1082              and in the <code>head</code> element.
1083              It cannot be used in e.g. <code>ul</code>, <code>table</code>,
1084              or <code>select</code>.</dd>
1085          <dt>If the element with the error is <code>blink</code>,
1086          <code>center</code>, or <code>marquee</code> element</dt>
1087              <dd>These elements are not part of the HTML standard.
1088              Use CSS for styling control.</dd>
1089    
1090          <dt><code>button</code>, <code>datalist</code>,
1091          <code>fieldset</code>, <code>form</code>,
1092          <code>input</code>, <code>label</code>,
1093          <code>optgroup</code>, <code>option</code>, <code>output</code>,
1094          <code>rb</code>, <code>rp</code>, <code>rt</code>, <code>ruby</code>,
1095          <code>textarea</code>, or <code>textarea</code> element</dt>
1096          <!-- rbc, rtc ? -->
1097              <dd>These elements are intentionally not supported by the conformance
1098              checker <em>yet</em>.</dd>
1099        </dl>        </dl>
1100      </p>      </p>
1101    </div>    </div>
1102    
1103    <div class="section" id="element-not-allowed:area"><h3>An <code>area</code> element cannot be used
1104      outside of a <code>map</code> element.</h3></div>
1105    
1106    <div class="section" id="element-not-allowed:base"><h3>There is another <code>base</code>
1107      element.</h3></div>
1108    
1109    <div class="section" id="element-not-allowed:datatemplate"><h3>In a <code>datatemplate</code> element, only
1110      <code>rule</code> elements are allowed.</h3></div>
1111    
1112    <div class="section" id="element-not-allowed:details-legend"><h3>In a <code>details</code> or <code>fieldset</code>
1113      element, only at the beginning of the element a <code>legend</code> element
1114      may be used.</h3></div>
1115    
1116    <div class="section" id="element-not-allowed:empty"><h3>Elements are not allowed in an empty
1117      element.</h3></div>
1118    
1119    <div class="section" id="element-not-allowed:figure-legend"><h3>In a <code>figure</code> element, only at the
1120      beginning or only at the end of the element a <code>lengend</code> element
1121      may be used.</h3></div>
1122    
1123    <div class="section" id="element-not-allowed:flow"><h3>This element is not allowed where flow
1124      content is expected.</h3></div>
1125    
1126    <div class="section" id="element-not-allowed:flow-style"><h3>A <code>style</code> element without
1127      <code>scoped</code> attribute is not allowed in this context.</h3></div>
1128    
1129    <div class="section" id="element-not-allowed:head-noscript"><h3>This element is not allowed in a
1130      <code>noscript</code> element in the <code>head</code> element.</h3></div>
1131    
1132    <div class="section" id="element-not-allowed:head-style"><h3>A <code>style</code> element with
1133      <code>scoped</code> attribute is not allowed in the <code>head</code>
1134      element.</h3></div>
1135    
1136    <div class="section" id="element-not-allowed:head-title"><h3>There is another <code>title</code>
1137      element.</h3></div>
1138    
1139    <div class="section" id="element-not-allowed:minus"><h3>This element is not allowed in this
1140      context.</h3></div>
1141    
1142    <div class="section" id="element-not-allowed:meta-charset"><h3>The character encoding declaration is not the
1143      first child element in the <code>head</code> element.</h3>
1144        <p>The character encoding declaration
1145        (<code class="html example">&lt;meta charset="<var>...</var>"&gt;</code> or
1146        <code class="html example">&lt;meta http-equiv=Content-Type content="text/html; charset=<var>...</var>"&gt;</code>
1147        must be the first child element in the <code>head</code> element.</p>
1148    
1149        <p>The character encoding declaration have to occur near the beginning
1150        of the document to ensure that Web browsers can be determine the
1151        character encoding of the document.</p>
1152    
1153        <p>The <code>title</code> element and other metadata elements must
1154        appear after any character encoding declaration is processed.</p>
1155      </div>
1156    
1157    <div class="section" id="element-not-allowed:metadata"><h3>This element is not allowed where metadata
1158      content is expected.</h3></div>
1159    
1160    <div class="section" id="element-not-allowed:phrasing"><h3>This element is not allowed where phrasing
1161      content is expected.</h3></div>
1162    
1163    <div class="section" id="element-not-allowed:root"><h3>This element is not allowed as the root
1164      element of a document.</h3>
1165        <p>An element that is not allowed as the root element
1166        is used as the root element of the document.  The document is
1167        non-conforming, as far as the conformance checker can tell.</p>
1168    
1169        <dl class="switch">
1170        <dt><code>html</code> element in an XHTML document</dt>
1171            <dd><p>In <abbr>XHTML</abbr> document, the root <code>html</code>
1172            element must have an <code>xmlns</code> attribute as:
1173              <pre class="xml example">
1174    <code>&lt;html xmlns="http://www.w3.org/1999/xhtml"&gt;</code></pre></p></dd>
1175        <dt><code>rss</code> element</dt>
1176            <dd><p>The document is written in some version of RSS.</p>
1177            <p>The conformance checker does not support any version
1178            of RSS.  Use Atom 1.0 for feed documents.</p></dd>
1179        <dt><code>feed</code> element</dt>
1180            <dd><p>The Atom <code>feed</code> element must be
1181            in the <code>http://www.w3.org/2005/Atom</code>
1182            namespace as:
1183              <pre class="xml example">
1184    <code>&lt;feed xmlns="http://www.w3.org/2005/Atom"&gt;</code></pre>
1185            </p>
1186            <p>The conformance checker does not support Atom 0.3.
1187            Use Atom 1.0 for feed documents.</p></dd>
1188        </dl>
1189      </div>
1190    
1191    <div class="section" id="element-not-allowed:root:xml"><h3>This element is not allowed as the root element
1192      of an XML document.</h3></div>
1193    
1194    <div class="section" id="element-not-allowed:ruby-base"><h3>This element is not allowed in the <code>ruby</code>
1195      element.</h3></div>
1196    
1197    <div class="section" id="element-not-allowed:text"><h3>This element is not allowed in this
1198      context.</h3></div>
1199    
1200    <div class="section" id="element-not-allowed:atom|content"><h3>This element is not allowed in an Atom
1201      <code>content</code> element.</h3></div>
1202    
1203    <div class="section" id="element-not-allowed:atom|PersonConstruct"><h3>This element is not allowed in Person
1204      construct.</h3></div>
1205    
1206    <div class="section" id="element-not-allowed:atom|TextConstruct"><h3>This element is not allowed in Text
1207      construct.</h3></div>
1208    
1209    <div class="section" id="element-not-defined"><h3>This element is not defined.</h3>
1210        <p>The element is not one of elements allowed
1211        in the latest version of relevant specifications.</p>
1212    
1213        <p>The element cannot be used.</p>
1214    
1215        <dl class="switch">
1216        <dt><code>event-source</code> element</dt>
1217            <dd>The element was renamed as <em><code>eventsource</code>
1218            element</em> (no hyphen).</dd>
1219        <dt><code>m</code> element</dt>
1220            <dd>The element was renamed as <em><code>mark</code>
1221            element</em>.</dd>
1222        </dl>
1223      </div>
1224    
1225    <div class="section" id="multiple-labelable-fae"><h3>More than one labelable form-associated element
1226      is associated to a <code>label</code> element.</h3></div>
1227    
1228    <div class="section" id="no-significant-content"><h3>No significant content is contained
1229      in this element.</h3></div>
1230    
1231    <div class="section" id="no-significant-content-before"><h3>There is no significant content
1232      before this element.</h3></div>
1233    
1234    <div class="section" id="no-significant-content-at-the-end"><h3>No significant content is contained
1235      at the end of this element.</h3></div>
1236    
1237    <div class="section" id="ps-element-missing"><h3>There is no <code><var>{text}</var></code>
1238      element before this element.</h3>
1239        <p>There must be an element before another element, but there
1240        is not.  The document is non-conforming.</p>
1241    
1242        <p>For example, there must be a <code>dt</code> element
1243        before any <code>dd</code> element.</p>
1244      </div>
1245    
1246    <div class="section" id="rp:syntax-error"><h3>The content of a <code>rp</code> element must
1247      be a parenthesis.</h3></div>
1248    
1249  </section>  </section>
1250    
1251  <section id="attribute-errors">  <section id="attribute-errors">
1252  <h2>Attribute Errors</h2>  <h2>Attribute Errors</h2>
1253    
1254  <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>
1255    is not specified.</h3>    is not specified.</h3>
1256      <p>A required attribute is not specified.  The document      <p>A required attribute is not specified.  The document
1257      is non-conforming.</p>      is non-conforming.</p>
1258    
1259      <p>Some attribute is defined as <i>required</i>.      <p>Some attribute is defined as <i>required</i>.
     For example, any <code>img</code> element must have  
     <code>alt</code> and <code>src</code> attributes specified.  
1260      Without required attributes specified, user agents      Without required attributes specified, user agents
1261      cannot provide the full functionality of the element      cannot provide full functionality of the element to the user.</p>
     to the user.</p>  
   </div>  
1262    
1263  <div class="section attribute-error" id="in-HTML:xml:lang"><h3>The <code>xml:lang</code> attribute is not      <dl class="switch">
1264    allowed in HTML document.</h3>      <dt>HTML <code>img</code> element</dt>
1265      <p>The <code>xml:lang</code> attribute is not allowed in          <dd>The <code>src</code> attribute must be specified.
1266      HTML document.  The document is non-conforming.</p>          Additionally, the <code>alt</code> attribute must be specified
1267            in many cases.</dd>
1268      <p>The <code>xml:lang</code> attribute in <code>null</code>      <dt>HTML <code>link</code> element</dt>
1269      namespace for HTML elements is defined as conforming only for          <dd>The <code>rel</code> attribute must be specified.
1270      XML document.</p>          Note that the <code>rev</code> attribute is obsolete.</dd>
1271        </dl>
1272      </div>
1273    
1274    <div class="section" id="attribute-missing:data|type"><h3>For an <code>object</code> at least one of
1275      <code>data</code> and <code>type</code> attributes must be
1276      specified.</h3></div>
1277    
1278    <div class="section" id="attribute-missing:href|target"><h3>For a <code>base</code> element, at least one of
1279      <code>href</code> and <code>target</code> attributes must be
1280      specified.</h3></div>
1281    
1282    <div class="section" id="attribute-missing:name|http-equiv"><h3>For a <code>meta</code> element with the
1283      <code>content</code> attribute specified, exactly one of
1284      <code>name</code> and <code>http-equiv</code> attributes must be
1285      specified.</h3></div>
1286    
1287    <div class="section" id="attribute-missing:name|http-equiv|charset"><h3>For a <code>meta</code> element, exactly one of
1288      <code>name</code>, <code>http-equiv</code>, and <code>charset</code>
1289      attributes must be specified.</h3></div>
1290    
1291    <div class="section" id="attribute-not-allowed"><h3>Attribute
1292      <code><var>{local-name}</var></code> is not allowed for
1293      <code><var>{element-local-name}</var></code> element.</h3>
1294        <p>An attribute is specified where it is not allowed.
1295        The document is non-conforming.</p>
1296    
1297        <dl>
1298        <dt>HTML <code>meta</code> element</dt>
1299            <dd>For HTML <code>meta</code> element, <em>only one</em> of
1300            <code>name</code>, <code>http-equiv</code>, or <code>charset</code>
1301            attribute is allowed.</dd>
1302        </dl>
1303      </div>
1304    
1305    <div class="section" id="attribute-not-allowed:ismap"><h3>The <code>ismap</code> attribute may only be
1306      used for the image contained in an <code>a</code> element.</h3></div>
1307    
1308    <div class="section" id="attribute-not-defined"><h3>This attribute is not defined.</h3>
1309        <p>The attribute is not one of attributes allowed for the element
1310        in the latest version of relevant specifications.</p>
1311    
1312        <p>The attribute cannot be used.</p>
1313    
1314        <dl class="switch">
1315        <dt><code>align</code> attribute (various HTML elements)</dt>
1316        <dt><code>border</code> attribute (various HTML elements)</dt>
1317          <dd>These attributes are no longer part of HTML.  You can use CSS
1318          properties to control the presentation of the element.</dd>
1319        <dt><code>autosubmit</code> attribute (<code>menu</code> element)</dt>
1320          <dd>The attribute was part of HTML5 draft but then dropped.
1321          Similar functionality can be implemented by scripts.</dd>
1322        <dt><code>language</code> attribute (<code>script</code> element)</dt>
1323          <dd>The attribute is no longer the standard way to specify the
1324          scripting language.  If you are using JavaScript, then no explicit
1325          specification of the scripting language is necessary, so you can
1326          write the element like:
1327            <p><code class="html example code">&lt;script&gt;<br><!--
1328            --> /* JavaScript code */<br><!--
1329            -->&lt;/script&gt;</code></p>
1330          If you are using different scripting language from JavaScript, or
1331          you want to declare the scripting language explicitly, you should
1332          use the <code>type</code> attribute, as follows:
1333            <dl class="switch">
1334            <dt>JavaScript</dt>
1335              <dd>Use
1336              <code class="html example">&lt;script type="text/javascript"&gt;</code>.</dd>
1337            <dt>VBScript</dt>
1338              <dd>Use
1339              <code class="html example">&lt;script type="text/vbscript"&gt;</code>.</dd>
1340            </dl>
1341          </dd>
1342        </dl>
1343      </div>
1344    
1345    <div class="section" id="_charset_-value"><h3>The <code>value</code> attribute cannot be
1346      specified to an <code>input</code> element whose <code>type</code>
1347      is <code>hidden</code> and <code>name</code> is
1348      <code>_charset_</code>.</h3></div>
1349    
1350    <div class="section" id="in-HTML:xml:lang"><h3>The <code>xml:lang</code> attribute in HTML
1351      document is ignored.</h3>
1352        <p>The <code>xml:lang</code> attribute does not have an effect in
1353        HTML document.</p>
1354    
1355        <p>The <code>xml:lang</code> attribute is only applicable to XML
1356        documents.  In HTML document, it is only allowed to ease migration
1357        from XML.</p>
1358    
1359      <p>To specify natural language information in HTML document,      <p>To specify natural language information in HTML document,
1360      use <code>lang</code> attribute instead.</p>      use <code>lang</code> attribute instead.</p>
1361    
1362        <p>XHTML 1.0 Appendix C was encouraged to specify both
1363        <code>lang</code> and <code>xml:lang</code> attributes with
1364        the same value.  Such a duplication has <em>no effect</em> in practice.
1365        Use only one of <code>lang</code> (in HTML) or <code>xml:lang</code> (in
1366        XML).</p>
1367    
1368      <!-- @@ ISSUE: xml:lang in non-HTML element in DOM5 HTML created      <!-- @@ ISSUE: xml:lang in non-HTML element in DOM5 HTML created
1369           from an HTML document? -->           from an HTML document? -->
1370    </div>    </div>
1371    
1372  <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
1373    allowed in XML document.</h3>    allowed in XML document.</h3>
1374      <p>The <code>charset</code> attribute of a      <p>The <code>charset</code> attribute of a
1375      <code>meta</code> element is not allowed in XML document.      <code>meta</code> element is not allowed in XML document.
# Line 350  Web Document Conformance Checker (BETA)< Line 1378  Web Document Conformance Checker (BETA)<
1378      <p>To specify the character encoding used for serialization,      <p>To specify the character encoding used for serialization,
1379      if necessary, use XML declaration instead:      if necessary, use XML declaration instead:
1380        <pre class="xml example">        <pre class="xml example">
1381  <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>
1382      </p>      </p>
1383    </div>    </div>
1384    
1385  <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
1386    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>  
1387    
1388      <p>The <code>lang</code> attribute in <code>null</code>  <div class="section" id="in-XML:xml:lang"><h3>The <code>xml:lang</code> attribute in no namespace
1389      namespace for HTML elements is defined as conforming only for    is only allowed in HTML document.</h3></div>
     HTML document.</p>  
   
     <p>To specify natural language information in XML document,  
     use <code>xml:lang</code> attribute instead.</p>  
   </div>  
1390    
1391  <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
1392    in the <code>null</code> namespace is not allowed in    in the <code>null</code> namespace is not allowed in
1393    XHTML document.  The document is non-conforming.</h3>    XHTML document.  The document is non-conforming.</h3>
1394      <p>The <code>xmlns</code> attribute in the <code>null</code>      <p>The <code>xmlns</code> attribute in the <code>null</code>
1395      namespace is not allowed in XHTML document.</p>      namespace is not allowed in XHTML document.</p>
1396    
1397      <p>This error should not occur in conformance-checking      <p>This error should not occur in conformance-checking of
1398      static documents.</p>      static documents.</p>
1399    </div>    </div>
1400    
1401    <div class="section" id="input-attr-not-applicable"><h3>This attribute is not applied to an
1402      <code>input</code> element whose <code>type</code> is
1403      <code><var>{text}</var></code>.</h3></div>
1404    
1405    <div class="section" id="non-ol-li-value"><h3>The <code>value</code> attribute cannot be
1406      specified to a <code>li</code> element whose parent element is
1407      not an <code>ol</code> element.</h3></div>
1408    
1409    <div class="section" id="xml:lang-not-allowed"><h3>The <code>xml:lang</code> attribute is only allowed
1410      when the <code>lang</code> attribute is specified.</h3></div>
1411    
1412  </section>  </section>
1413    
1414  <section id="attribute-value-errors">  <section id="attribute-value-errors">
1415  <h2>Attribute Value Errors</h2>  <h2>Attribute Value Errors</h2>
1416    
1417  <div class="section attribute-value-error" id="enumerated:invalid"><h3>This attribute only allow a limited set of  <div class="section" id="boolean:invalid"><h3>Attribute value <code><var>{@}</var></code>
1418    values and the specified value is not one of them.</h3></div>    is not allowed.  It must be an empty string or a string
1419      <code><var>{local-name}</var></code>.</h3></div>
1420    
1421    <div class="section" id="char:syntax-error"><h3>The attribute value must be exactly one
1422      character.</h3></div>
1423    
1424    <div class="section" id="charref-in-charset"><h3>A character reference cannot be used to
1425      represent a character encoding name.</h3></div>
1426    
1427    <div class="section" id="charset:not-ascii-compat"><h3>Characeter encoding <code><var>{value}</var></code>
1428      is not ASCII compatible.</h3></div>
1429    
1430    <div class="section" id="charset:not-preferred"><h3>Character encoding name
1431      <code><var>{value}</var></code> is not the preferred name of that
1432      character encoding.</h3></div>
1433    
1434    <div class="section" id="charset:not-registered"><h3>Character encoding name
1435      <code><var>{value}</var></code> is not a registered name.</h3>
1436        <p>The specified character encoding name is not registered to
1437        <abbr>IANA</abbr>.  Use of registered character encoding name
1438        is a good practice to facilitate interoperability.</p>
1439    
1440        <dl class="switch">
1441        <dt><code>EUC-TW</code></dt>
1442          <dd><code>EUC-TW</code> is not registered.  Unfortunately, there
1443          is no registered name for that character encoding.  Use
1444          Big5 encoding with character encoding name <code>Big5</code>
1445          if it is enough to represent the document.</dd>
1446        <dt><code>ISO-2022-JP-1</code></dt>
1447          <dd><code>ISO-2022-JP-1</code> is not registered, nevertheless
1448          this character encoding name is documented in
1449          <a href="urn:ietf:rfc:2237"><abbr>RFC</abbr> 2237</a>.  Use
1450          <code>ISO-2022-JP-2</code> instead, since that character encoding
1451          is a superset of ISO-2022-JP-1.</dd>
1452        <dt><code>ISO-2022-JP-3</code>, <code>ISO-2022-JP-3-plane1</code></dt>
1453          <dd>These names are not registered and obsoleted in favor of
1454          <code>ISO-2022-JP-2004</code> and
1455          <code>ISO-2022-JP-2004-plane1</code>.</dd>
1456        <dt><code>ISO-2022-JP-2003</code>,
1457        <code>ISO-2022-JP-2003-plane1</code></dt>
1458          <dd>These names are not registered and corrected to
1459          <code>ISO-2022-JP-2004</code> and
1460          <code>ISO-2022-JP-2004-plane1</code>.</dd>
1461        <dt><code>ISO-2022-JP-2004</code>,
1462        <code>ISO-2022-JP-2004-plane1</code></dt>
1463          <dd>These names are not registered.  Unfortunately, there is
1464          no registered name for these character encodings.</dd>
1465        <dt><code>UTF-8N</code></dt>
1466          <dd><code>UTF-8N</code> is not registered.  Character encoding
1467          name <code>UTF-8</code> represents UTF-8 encoding with or
1468          without <abbr>BOM</abbr>.</dd>
1469        </dl>
1470    
1471        <p><strong>WARNING</strong>: This error might be raised for
1472        a registered character encoding name, since the character encoding
1473        name database of the conformance checker is not complete yet.</p>
1474      </div>
1475    
1476    <div class="section" id="charset:private"><h3>Character encoding name
1477      <code><var>{value}</var></code> is a private name.</h3>
1478        <p>The specified character encoding name is a private name and
1479        not registered to <abbr>IANA</abbr>.  Use of registered character
1480        encoding name is a good practice to facilitate interoperability.</p>
1481    
1482        <dl class="switch">
1483        <dt><code>x-euc-jp</code></dt>
1484          <dd>Use <code>EUC-JP</code> for the Japanese <abbr>EUC</abbr>
1485          character encoding.</dd>
1486        <dt><code>x-sjis</code></dt>
1487          <dd>Use <code>Shift_JIS</code> for standard Shift encoding scheme of
1488          <abbr>JIS</abbr> coded character set, or <code>Windows-31J</code>
1489          for Microsoft standard character set as implemented by
1490          Microsoft Windows.</dd>
1491        </dl>
1492      </div>
1493    
1494    <div class="section" id="charset:syntax-error"><h3>The specified value <code><var>{value}</var></code>
1495      is syntactically not a character encoding name.</h3>
1496        <p>The attribute value must be a character encoding name.  However,
1497        the specified value is not a character encoding name syntactically.
1498        The document is non‐conforming.</p>
1499        <p>Character encoding name is a string of <abbr>ASCII</abbr>
1500        printable characters, up to 40 characters.</p>
1501      </div>
1502    
1503    <div class="section" id="color:syntax-error"><h3>The specified value is not a color
1504      name or hexadecimal color number.</h3></div>
1505    
1506    <div class="section" id="coords:number-not-3"><h3>The <code>coords</code> attribute have to
1507      contain three (3) numbers (specified:
1508      <code><var>{text}</var></code>).</h3></div>
1509    
1510    <div class="section" id="coords:number-not-4"><h3>The <code>coords</code> attribute have to
1511      contain four (4) numbers (specified:
1512      <code><var>{text}</var></code>).</h3></div>
1513    
1514    <div class="section" id="coords:number-lt-6"><h3>The <code>coords</code> attribute have to
1515      contain more than or equal to six (6) numbers (specified:
1516      <code><var>{text}</var></code>).</h3></div>
1517    
1518    <div class="section" id="coords:number-not-even"><h3>The <code>coords</code> attribute have to
1519      contain even number of numbers (specified:
1520      <code><var>{text}</var></code>).</h3></div>
1521    
1522    <div class="section" id="coords:out-of-range"><h3>The specified value <code><var>{value}</var></code>
1523      is out of range.</h3></div>
1524    
1525    <div class="section" id="coords:syntax-error"><h3>The specified value is not valid.</h3></div>
1526    
1527    <div class="section" id="datetime:bad-year"><h3>Year number is out of range.</h3></div>
1528    
1529    <div class="section" id="datetime:bad-month"><h3>Month number is out of range.</h3></div>
1530    
1531    <div class="section" id="datetime:bad-day"><h3>Day number is out of range.</h3></div>
1532    
1533    <div class="section" id="datetime:bad-hour"><h3>Hour number is out of range.</h3></div>
1534    
1535    <div class="section" id="datetime:bad-minute"><h3>Minute number is out of range.</h3></div>
1536    
1537    <div class="section" id="datetime:bad-second"><h3>Second number is out of range.</h3></div>
1538    
1539    <div class="section" id="datetime:bad-timezone-hour"><h3>Hour number of the timezone component is out of
1540      range.</h3></div>
1541    
1542    <div class="section" id="datetime:bad-timezone-minute"><h3>Minute number of the timezone component is out of
1543      range.</h3></div>
1544    
1545    <div class="section" id="datetime:syntax-error"><h3>The value is not a datetime.</h3></div>
1546    
1547    <div class="section" id="dateortime:syntax-error"><h3>The value is not a date or time.</h3></div>
1548    
1549    <div class="section" id="empty-form-name"><h3>Form name is empty.</h3></div>
1550    
1551    <div class="section" id="enumerated:invalid"><h3>This attribute only allow a limited set of
1552      values and the specified value <code><var>{@}</var></code> is not one
1553      of them.</h3>
1554        <p>For this attribute only several values are allowed and the
1555        value of the attribute is not one of them.  The document
1556        is non-conforming.</p>
1557    
1558        <dl>
1559        <dt>HTML <code>meta</code> element, <code>http-equiv</code> attribute</dt>
1560            <dd><p>Only values <code>Default-Style</code> and <code>Refresh</code>
1561            are allowed.</p>
1562            <p>Value <code>Content-Type</code> is obsolete; for charset
1563            declaration, the <code>charset</code> attribute can be used as:
1564            <pre class="html example">
1565    <code>&lt;meta charset="<var>charset-name</var>"&gt;</code></pre>
1566            ... where <var>charset-name</var> is a name of the character encoding
1567            of the document, such as <code>utf-8</code>.</p>
1568            <p>Values <code>Content-Style-Type</code> and
1569            <code>Content-Script-Type</code> are currently not allowed.</p>
1570            <p>Value <code>Keywords</code> is not allowed.  Use
1571            <code>name</code> attribute instead of <code>http-equiv</code>
1572            attribute.</p>
1573            <p>Values <code>Expires</code>, <code>Pragma</code>,
1574            and <code>Cache-Control</code> are not allowed;
1575            use <em>real</em> HTTP header fields for cache control.</p></dd>
1576        </dl>
1577      </div>
1578    
1579    <div class="section" id="enumerated:invalid:http-equiv:content-type"><h3>Character encoding declaration syntax
1580      <code class="html bad example">&lt;meta http-equiv="Content-Type" content="text/html; charset=<var>charset-name</var>"&gt;</code>
1581      is obsolete.</h3>
1582        <p>Old long character encoding declaration syntax
1583        <code class="html bad example">&lt;meta http-equiv="Content-Type" content="text/html; charset=<var>charset-name</var>"&gt;</code>
1584        is in use.  The document is non‐conforming.</p>
1585    
1586        <p>The new character encoding declaration syntax is:
1587          <pre class="html example">
1588    <code>&lt;meta charset="<var>charset-name</var>"&gt;</code></pre>
1589        </p>
1590      </div>
1591    
1592  <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>
1593      is not allowed.</h3></div>
1594    
1595    <div class="section" id="duplicate-form-name"><h3>Form name <code><var>{value}</var></code> is already
1596      used for another element.</h3></div>
1597    
1598    <div class="section" id="duplicate-http-equiv"><h3>There is another pragma
1599      <code><var>{value}</var></code>.</h3></div>
1600    
1601    <div class="section" id="duplicate-ID"><h3>This identifier has already been
1602    assigned to another element.</h3></div>    assigned to another element.</h3></div>
1603    
1604  <div class="section attribute-value-error" id="reserved-browsing-context-name"><h3>This browsing context name is reserved.</h3></div>  <div class="section" id="duplicate-token"><h3>The token <code><var>{value}</var></code>
1605      appears in the attribute value twice.</h3></div>
1606    
1607    <div class="section" id="empty-anchor-image-alt"><h3>The <code>alt</code> attribute value is
1608      empty.</h3></div>
1609    
1610    <div class="section" id="empty-area-alt"><h3>The <code>alt</code> attribute value is
1611      empty.</h3>
1612        <p>The value of the <code>alt</code> attribute of an <code>area</code>
1613        element is an empty value.</p>
1614    
1615        <p>In general, the <code>alt</code> attribute value cannot be empty.
1616        It must provide an alternative text for the hyperlink represented by
1617        the <code>area</code> element.  The alternative text is to be used
1618        when the Web browser cannot display the image, or is configured not
1619        to display images.</p>
1620    
1621        <p>As an exception, the <code>alt</code> attribute may be left blank
1622        if the same image map (i.e. the ancestor <code>map</code> element)
1623        contains another <code>area</code> element whose <code>href</code>
1624        attribute references the same resource as the <code>href</code>
1625        attribute of the <code>area</code> element in question, and the other
1626        <code>area</code> element has an <code>alt</code> attribute with
1627        non‐empty value.</p>
1628      </div>
1629    
1630    <div class="section" id="empty-attribute-value"><h3>The attribute value is empty.</h3></div>
1631    
1632    <div class="section" id="empty-style-sheet-title"><h3>The value of the <code>title</code> attribute
1633      is empty.</h3>
1634        <p>The <code>title</code> attribute value of the <code>link</code>
1635        element that defines an alternate style sheet is an empty value.</p>
1636    
1637        <p>A <code>link</code> element whose <code>rel</code> attribute
1638        is <code>alternate stylesheet</code> defines an alternate style sheet.
1639        An alternate style sheet must be associated with a name using the
1640        <code>title</code> attribute.  The name cannot be empty.</p>
1641      </div>
1642    
1643    <div class="section" id="float:out-of-range"><h3>The specified value is out of range.</h3></div>
1644    
1645    <div class="section" id="float:syntax-error"><h3>The attribute value is not a real
1646      number.</h3></div>
1647    
1648    <div class="section" id="fragment-points-itself"><h3>A fragment identifier references the element
1649      itself.</h3></div>
1650    
1651    <div class="section" id="fragment-points-nothing"><h3>A fragment identifier references no
1652      node.</h3></div>
1653    
1654    <div class="section" id="hashref:syntax-error"><h3>A hash−name reference must start with a
1655      <code>#</code> character.</h3></div>
1656    
1657    <div class="section" id="id-ne-name"><h3>The <code>id</code> attribute value is
1658      different from the <code>name</code> attribute value.</h3></div>
1659    
1660    <div class="section" id="integer:syntax-error"><h3>The attribute value is not an integer.</h3></div>
1661    
1662    <div class="section" id="link-type:bad-context"><h3>The link type <code><var>{value}</var></code>
1663      cannot be specified for this element.</h3>
1664        <p>The specified link type cannot be used for the element.
1665        The document is non-conforming.</p>
1666    
1667        <p>Link types are associated with limited set of elements.
1668        They cannot be used with other elements.</p>
1669    
1670        <p>For example, link type <code>bookmark</code>
1671        can be used with <code>a</code> or <code>area</code> element,
1672        while it cannot be used with <code>link</code> element.</p>
1673      </div>
1674    
1675    <div class="section" id="invalid-attribute-value"><h3>Attribute value <code><var>{@}</var></code>
1676      is not an allowed value.</h3></div>
1677    
1678    <div class="section" id="length:syntax-error"><h3>The attribute value is not a length
1679      value.</h3></div>
1680    
1681    <div class="section" id="link-type:non-conforming"><h3>The link type <code><var>{value}</var></code>
1682      is non-conforming.</h3>
1683        <p>The specified link type is non-conforming, and therefore
1684        the document is non-conforming.</p>
1685    
1686        <dl class="switch">
1687        <dt>Link type <code>contents</code></dt>
1688          <dd>Use link type <code>index</code>.</dd>
1689        <dt>Link type <code>copyright</code></dt>
1690          <dd>Use link type <code>license</code>.</dd>
1691        <dt>Link type <code>home</code></dt>
1692          <dd>Use link type <code>index</code>.</dd>
1693        <dt>Link type <code>previous</code></dt>
1694          <dd>Use link type <code>prev</code>.</dd>
1695        <dt>Link type <code>start</code></dt>
1696          <dd>Use link type <code>first</code>.</dd>
1697        <dt>Link type <code>toc</code> or <code>top</code></dt>
1698          <dd>Use link type <code>index</code>.</dd>
1699        </dl>
1700      </div>
1701    
1702    <div class="section" id="meta-content-type-syntax-error"><h3>The specified value is not a valid as a long
1703      character encoding declaration.</h3></div>
1704    
1705    <div class="section" id="mismatched-charset-name"><h3>The specified character encoding name
1706      <code><var>{value}</var></code> is different from the actual document
1707      character encoding <code><var>{text}</var></code>.</h3>
1708        <p>The specified character encoding name is different from
1709        the character encoding of the document.  The document
1710        is non‐conforming.</p>
1711      </div>
1712    
1713    <div class="section" id="mismatched-charset-name-not-checked"><h3>Whether the specified character encoding name
1714      <code><var>{value}</var></code> matches to the actual character encoding
1715      name cannot be checked since the input is not a byte stream.</h3></div>
1716    
1717    <div class="section" id="mode:syntax-error"><h3>The attribute value is not a valid mode
1718      name.</h3></div>
1719    
1720    <div class="section" id="nninteger:out-of-range"><h3>The specified value is out of range.</h3></div>
1721    
1722    <div class="section" id="nninteger:syntax-error"><h3>The attribute value is not a non‐negative
1723      integer.</h3></div>
1724    
1725    <div class="section" id="no-referenced-form"><h3>The element referneced by the <code>form</code>
1726      attribute is not a <code>form</code> element, or no element is
1727      found.</h3></div>
1728    
1729    <div class="section" id="no-referenced-map"><h3>The element referneced by the <code>usemap</code>
1730      attribute is not a <code>map</code> element, or no element is
1731      found.</h3></div>
1732    
1733    <div class="section" id="no-referenced-menu"><h3>The element referneced by the
1734      <code>contextmenu</code> attribute is not a <code>menu</code> element, or
1735      no element is found.</h3></div>
1736    
1737    <div class="section" id="no-referenced-header-cell"><h3>There is no table header cell whose <code>id</code>
1738      is <code><var>{value}</var></code> in the same table.</h3></div>
1739    
1740    <div class="section" id="refresh:syntax-error"><h3>the specified value is not a valid as part
1741      of a <code>Refresh</code> pragma.</h3></div>
1742    
1743    <div class="section" id="repeat:syntax-error"><h3>The attribute value is not an integer or
1744      a string <code>template</code>.</h3></div>
1745    
1746    <div class="section" id="reserved-browsing-context-name"><h3>Browsing context name
1747      <code><var>{@}</var></code> is reserved.</h3>
1748        <p>The specified browsing context name is reserved.
1749        The document is non-conforming.</p>
1750    
1751        <p>Names of browsing contexts starting with <code>_</code>
1752        (<code>U+005F</code> <code class="charname">LOW LINE</code>)
1753        are reserved so that it must not be used.</p>
1754    
1755        <p>Old version of HTML, non-HTML markup languages, and
1756        Web browsers define or implements special reserved
1757        browsing context names <code>_blank</code>,
1758        <code>_main</code>, and <code>_replace</code>.
1759        However, they are <em>not</em> conforming attribute values.</p>
1760      </div>
1761    
1762    <div class="section" id="Reserved-Prefixes-and-Namespace-Names:Name"><h3>Namespace name <code><var>{text}</var></code>
1763      is reserved and cannot be used for an arbitrary prefix.</h3></div>
1764    
1765    <div class="section" id="Reserved-Prefixes-and-Namespace-Names:Prefix"><h3>Namespace prefix <code><var>{text}</var></code>
1766      is reserved and cannot be used for an arbitrary namespace name.</h3></div>
1767    
1768    <div class="section" id="link-type:proposed"><h3>Link type <code><var>{value}</var></code>
1769      is proposed but not accepted yet; it <em>should not</em> be
1770      used until it has been accepted.</h3>
1771        <p>The link type is in the <i>proposed</i> status; it
1772        <em>should not</em> be used until it has been
1773        accepted.</p>
1774    
1775        <p><strong>Warning</strong>: The data served to the
1776        conforming checker might be out of date; it might have already
1777        been accepted or rejected.  The document might or might not be
1778        conforming depending on the status.  See WHATWG Wiki
1779        for the latest information.</p>
1780      </div>
1781    
1782    <div class="section" id="sizes:syntax-error"><h3>The specified value <code><var>{value}</var></code>
1783      is not a valid value.</h3></div>
1784    
1785    <div class="section" id="space-in-ID"><h3>White space characters are not allowed
1786      in the <code>id</code> attribute.</h3></div>
1787    
1788    <div class="section" id="template:not-template"><h3>The node referenced by the <code>template</code>
1789      attribute is not a template.</h3></div>
1790    
1791    <div class="section" id="value-too-long"><h3>The <code>value</code> attribute value is longer
1792      than the value of the <code>maxlength</code> attribute.</h3></div>
1793    
1794    <div class="section" id="window-name:empty"><h3>Browsing context name must not be empty.</h3></div>
1795    
1796    <div class="section" id="window-name:reserved"><h3>Browsing context name
1797      <code><var>{value}</var></code> is reserved.</h3></div>
1798    
1799    <div class="section" id="word-not-allowed"><h3>The word <code><var>{value}</var></code> is not
1800      allowed in this attribute.</h3></div>
1801    
1802    <div class="section" id="XML-1.0-NCName:syntax-error"><h3>The specified value is not a legal XML Namespaces
1803      1.0 <code>NCName</code>.</h3></div>
1804    
1805    <div class="section" id="xml:lang-ne-lang"><h3>The value of the <code>xml:lang</code> attribute
1806      is different from the value of the <code>lang</code> attribute.</h3>
1807        <p>The value of the <code>xml:lang</code> attribute (either the
1808        <code>lang</code> attribute in the <code>xml</code> (i.e.
1809        <code>http://www.w3.org/XML/1998/namespace</code>) namespace, or
1810        the <code>xml:lang</code> attribute in no namespace) for the element has
1811        different value than that of the <code>lang</code> attribute in no
1812        namespace.</p>
1813    
1814        <p>For historical reason, there are two attributes applicable to HTML
1815        elements to specify language information of an element: <code>lang</code>
1816        and <code>xml:lang</code>.  In HTML documents, only <code>lang</code>
1817        attribute in no namespace is allowed and take effect; the
1818        <code>xml:lang</code> attribute in no namespace is ignored in HTML
1819        documents.  In XHTML documents, both <code>lang</code> and
1820        <code>xml:lang</code> attributes are allowed.</p>
1821    
1822        <p>In general, <em>only the <code>lang</code> attribute</em> need to be
1823        specified for an element.</p>
1824    
1825        <p>If both <code>lang</code> and <code>xml:lang</code> attributes are
1826        specified on the same element, their values must be the same value.</p>
1827      </div>
1828    
1829  </section>  </section>
1830    
1831  <section id="table-model-errors">  <section id="table-model-errors">
1832  <h2>Table Model Errors</h2>  <h2>Table Model Errors</h2>
1833    
1834  <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
1835      multiple cells.</h3></div>
1836    
1837    <div class="section" id="colspan-creates-column-with-no-anchored-cell"><h3>This <code>colspan</code> attribute
1838    results in creating a table column that does not contain    results in creating a table column that does not contain
1839    any cell anchored to it.</h3></div>    any cell anchored to it.</h3></div>
1840    
1841  <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>
1842    
1843    <div class="section" id="table:no-cell-in-last-row"><h3>The table has no cell (<code>td</code> or
1844    <code>th</code>) in the last row.</h3></div>    <code>th</code>) in the last row.</h3></div>
1845    
1846    <div class="section" id="table:rowspan-extends-table"><h3>This <code>rowspan</code> attribute
1847      results in creating a table row that does not contain
1848      any cell anchored to it.</h3>
1849        <p>The <code>rowspan</code> attribute value of the cell
1850        is so specified that it extends a table in the row axis.
1851        However, the extended row does not contain any cell by itself.
1852        The document is non-conforming.</p>
1853    
1854        <p>For example, the table below is non-conforming:
1855          <pre class="html bad example">
1856    <code>&lt;table&gt;
1857    &lt;tbody&gt;
1858    &lt;tr&gt;&lt;td rowspan=2&gt;&lt;/td&gt;&lt;/tr&gt;
1859    &lt;/tbody&gt;
1860    &lt;/table&gt;</code></pre>
1861        ... since the second row contains only
1862        a cell that spans between first and second rows.</p>
1863      </div>
1864    
1865    <div class="section" id="row-with-no-anchored-cell"><h3>This row has no anchored cell.</h3></div>
1866    
1867    <div class="section" id="rowspan-creates-row-with-no-anchored-cell"><h3>This <code>rowspan</code> attribute
1868      results in creating a table row that does not contain
1869      any cell anchored to it.</h3></div>
1870    
1871    
1872  </section>  </section>
1873    
1874  <section id="imt-warnings">  <section id="imt-warnings">
1875  <h2>Internet Media Type Warnings</h2>  <h2>Internet Media Type Errors</h2>
1876    
1877    <div class="section" id="boundary:syntax-error"><h3>The specified value is not a valid value
1878      as a multipart boundary.</h3></div>
1879    
1880  <div class="section should" id="s:IMT:obsolete-subtype"><h3>An <em>obsolete</em> subtype is used.</h3></div>  <div class="section" id="e4x:syntax-error"><h3>The specified value is not a valid value
1881      for the attribute <code>e4x</code>.</h3></div>
1882    
1883  <div class="section should" id="s:IMT:private-subtype"><h3>A private (<code>x-</code> or <code>x.</code>)  <div class="section" id="IMT:attribute-syntax-error"><h3>The specified value,
1884    subtype is used.</h3></div>    <code><var>{value}</var></code>, is syntactically not a valid
1885      attribute name.</h3></div>
1886    
1887    <div class="section" id="IMT:composite"><h3>The specified media type is a composite
1888      type, which is not allowed in this context.</h3></div>
1889    
1890    <div class="section" id="IMT:limited-use-subtype"><h3>An Internet Media Type whose intended usage
1891      is limited use, <code><var>{value}</var></code> is used.</h3></div>
1892    
1893    <div class="section" id="IMT:syntax-error"><h3>The specified value is not an Internet Media
1894      Type.</h3></div>
1895    
1896    <div class="section" id="IMT:obsolete-parameter"><h3>An obsolete parameter
1897      <code><var>{value}</var></code> is used.</h3></div>
1898    
1899    <div class="section" id="IMT:obsolete-subtype"><h3>An obsolete Internet Media Type
1900      <code><var>{value}</var></code> is used.</h3>
1901        <p>The specified Internet Media Type is registered with its intended
1902        usage as <i>OBSOLETE</i>.</p>
1903        
1904        <dl class="swtich">
1905        <dt>Media type <code>text/ecmascript</code></dt>
1906          <dd>Media type <code>text/ecmascript</code> is obsoleted in
1907          favor of <code>application/ecmascript</code>.  Note that
1908          <em><code>text/javascript</code></em> would be the better alternative
1909          in many cases.</dd>
1910        <dt>Media type <code>text/javascript</code></dt>
1911          <dd>Media type <code>text/javascript</code> is obsoleted by
1912          <abbr>IETF</abbr> with backward incompatible alternate
1913          <code>application/javascript</code> for architectural
1914          purity.<!-- @@ ref? -->  Those who prefer reality to academic
1915          purity <em>may ignore</em> this warning.</dd>
1916        </dl>
1917      </div>
1918    
1919    <div class="section" id="IMT:parameter-missing"><h3>Parameter <code><var>{text}</var></code> have to
1920      be specified for the Internet Media Type
1921      <code><var>{value}</var></code>.</h3></div>
1922    
1923    <div class="section" id="IMT:parameter-not-allowed"><h3>Parameter <code><var>{value}</var></code> is not
1924      allowed for this Internet Media Type.</h3></div>
1925    
1926    <div class="section" id="IMT:private-subtype"><h3>Use of a private Internet Media Type
1927      <code><var>{value}</var></code> is not encouraged.</h3></div>
1928    
1929    <div class="section" id="IMT:private-type"><h3>Use of a private type
1930      <code><var>{value}</var></code> is not encouraged.</h3></div>
1931    
1932    <div class="section" id="IMT:subtype-syntax-error"><h3>Value <code><var>{value}</var></code> is
1933      syntactically not a valid subtype value of an Internet Media Type.</h3></div>
1934    
1935    <div class="section" id="IMT:type-syntax-error"><h3>Value <code><var>{value}</var></code> is
1936      syntactically not a valid type.</h3></div>
1937    
1938    <div class="section" id="IMT:unknown-parameter"><h3>An unknown parameter <code><var>{value}</var></code>
1939      is used.  The conformance checker cannot determine whether use of this
1940      parameter is valid or not.</h3></div>
1941    
1942    <div class="section" id="IMT:unknown-subtype"><h3>An unknown Internet Media Type
1943      <code><var>{value}</var></code> is used.  At the time of the update of
1944      the conformance checker's Internet Media Type database, the subtype is
1945      not reigstered to the IANA registry.  The subtype, however, might be
1946      registerd to the IANA registry thereafter.  Please consult the IANA
1947      registry.</h3></div>
1948    
1949    <div class="section" id="IMT:unregistered-subtype"><h3>Use of an Internet Media Type
1950      <code><var>{value}</var></code> is not encouraged since it is not
1951      part of the IANA registry.</h3></div>
1952    
1953    <div class="section" id="IMT:unregistered-type"><h3>Use of a type
1954      <code><var>{value}</var></code> is not encouraged since it is not
1955      a standardized type.</h3></div>
1956    
1957  <div class="section should" id="s:IMT:unregistered-subtype"><h3>The subtype is not registered to IANA.</h3></div>  <div class="section" id="not-IMT"><h3>A value that is not an Internet Media Type
1958      is not allowed here.</h3></div>
1959    
1960  </section>  </section>
1961    
1962  <section id="uri-errors">  <section id="uri-errors">
1963  <h2>URI (or IRI) Errors</h2>  <h2>URL Errors</h2>
1964    
1965  <div class="section must" id="m:URI::syntax-error"><h3>This string is not an IRI syntactically.</h3></div>  <div class="section" id="syntax-error:iri3987"><h3>The specified value is syntactically not an
1966      IRI.</h3></div>
1967    
1968  </section>  <div class="section" id="syntax-error:iriref3987"><h3>The specified value is syntactically not an IRI
1969      reference.</h3>
1970        <p>The specified value does not satisfy the syntactical requirements
1971        for IRI references.  The document is non-conforming.</p>
1972    
1973        <p>Possible causes:
1974          <ul>
1975          <li>The string might contain one or more white space characters.
1976          Especially, the <code> </code> (<code>U+0020</code>
1977          <code class="charname">SPACE</code>) character cannot be
1978          used in IRI references.</li>
1979          </ul>
1980        </p>
1981      </div>
1982    
1983    <div class="section" id="syntax-error:rdfuriref"><h3>The specified value is syntactically not an RDF
1984      URI reference.</h3></div>
1985    
1986    <div class="section" id="syntax-error:uri2396"><h3>The specified value is syntactically not a
1987      URI according to RFC 2396.</h3></div>
1988    
1989    <div class="section" id="syntax-error:uri3986"><h3>The specified value is syntactically not a
1990      URI.</h3></div>
1991    
1992    <div class="section" id="URL:address-format"><h3>URL host address format
1993      <code><var>{text}</var></code> is not defined.</h3></div>
1994    
1995  <section id="uri-warnings">  <div class="section" id="URL:default-port"><h3>Default port number should be omitted.</h3></div>
 <h2>URI (or IRI) Warnings</h2>  
1996    
1997  <div class="section should" id="s:URI::dot-segment"><h3>Dot-segment (<code>.</code> or  <div class="section" id="URL:dot-segment"><h3>A dot-segment (<code>.</code> or
1998    <code>..</code>) should not occur in an absolute reference.</h3>    <code>..</code>) occurs in an absolute reference.</h3>
1999      <p>Dot-segment (<code>.</code> or <code>..</code>) should      <p>Dot-segment (<code>.</code> or <code>..</code>) should
2000      not occur in an absolute reference.</p>      not occur in an absolute reference.</p>
2001    
# Line 438  Web Document Conformance Checker (BETA)< Line 2006  Web Document Conformance Checker (BETA)<
2006      canonical form before it has been published.</p>      canonical form before it has been published.</p>
2007    </div>    </div>
2008    
2009  <div class="section should" id="s:URI::empty-path"><h3>This IRI should explicitly end with  <div class="section" id="URL:empty-host"><h3>The host component of the URL is empty.</h3></div>
2010    <code>/</code>.</h3></div>  
2011    <div class="section" id="URL:empty-path"><h3>The URL does not end with
2012      a <code>/</code> character.</h3></div>
2013    
2014    <div class="section" id="URL:empty-port"><h3>The port component of the URL is empty.</h3></div>
2015    
2016    <div class="section" id="URL-fragment-not-allowed"><h3>The fragment component of the URL is not
2017      allowed.</h3></div>
2018    
2019    <div class="section" id="URL:long-host"><h3>The host component of the URL
2020      is too long.</h3></div>
2021    
2022    <div class="section" id="URL:lowercase-hexadecimal-digit"><h3>A lowercase hexadecimal digit is used
2023      in percent-encoding.</h3>
2024        <p>The hexadecimal digit in percent-encoding string in the IRI
2025        is in lowercase.  Though the IRI <em>is</em> conforming,
2026        it should be in uppercase.</p>
2027      </div>
2028    
2029    <div class="section" id="URL:non-DNS-host"><h3>The host component of the URL
2030      is not a DNS host name.</h3></div>
2031    
2032    <div class="section" id="URL:non-UTF-8-host"><h3>The host component of the URL
2033      is not encoded in UTF-8.</h3></div>
2034    
2035    <div class="section" id="URL:password"><h3>Password should not be included in a URL
2036      for the security.</h3></div>
2037    
2038    <div class="section" id="URL:percent-encoded-unreserved"><h3>An unreserved character is
2039      percent-encoded.</h3>
2040        <p>An unreserved character is percent-encoded in the IRI.
2041        Though it <em>is</em> conforming, it should be in the
2042        decoded (or bare) form.</p>
2043      </div>
2044    
2045    <div class="section" id="URL:uppercase-host"><h3>The host <code><var>{value}</var></code>
2046      should be spelt in lowercase.</h3></div>
2047    
2048    <div class="section" id="URL:uppercase-scheme-name"><h3>URL scheme name is in uppercase.</h3>
2049        <p>The scheme part of the IRI is written in uppercase letter.</p>
2050    
2051        <p>Uppercase scheme names are not required to be processed
2052        correctly.</p>
2053    <!-- @@
2054     RFC 3986 3.1.
2055     > Although schemes are case-
2056       insensitive, the canonical form is lowercase and documents that
2057       specify schemes must do so with lowercase letters.
2058    
2059     > An implementation ... should only produce lowercase scheme names for
2060       consistency.
2061    -->
2062      </div>
2063    
2064    </section>
2065    
2066    <section id="mq-errors">
2067    <h2>Media Query Errors</h2>
2068    
2069    <div class="section" id="mq-syntax-error"><h3>The specified value has a syntax error as a
2070      media query.</h3></div>
2071    
2072    <div class="section" id="unknown-media-type"><h3>Media type <code><var>{value}</var></code> is
2073      not supported by the conformance checker.</h3></div>
2074    
2075    </section>
2076    
2077    <section id="selectors-errors">
2078    <h2>Selectors Errors</h2>
2079    
2080    <div class="section" id="an+b-not-closed"><h3>Argument list of the pseudo-class is
2081      not closed by a <code>)</code> character.</h3></div>
2082    
2083    <div class="section" id="ab+b-not-integer"><h3>Numbers in the argument
2084      <code><var>a</var>n+<var>b</var></code> have to be integers.</h3></div>
2085    
2086    <div class="section" id="an+b-syntax-error"><h3>Argument <code><var>a</var>n+<var>b</var></code> is
2087      syntactically incorrect.</h3></div>
2088    
2089    <div class="section" id="attr-selector-not-closed"><h3>Attribute selector is not closed by
2090      a <code>]</code> character.</h3></div>
2091    
2092    <div class="section" id="lang-selector-not-closed"><h3>Argument list of the <code>:lang</code>
2093      selector is not closed by a <code>)</code> character.</h3></div>
2094    
2095    <div class="section" id="namespace-prefix:not-declared"><h3>Namespace prefix <code><var>{value}</var></code>
2096      is not declared.</h3></div>
2097    
2098    <div class="section" id="no-attr-local-name"><h3>Attribute local name is missing.</h3></div>
2099    
2100    <div class="section" id="no-attr-match"><h3>Attribute matching operator (e.g.
2101      <code>=</code>) is missing.</h3></div>
2102    
2103    <div class="section" id="no-attr-name"><h3>Attribute name is missing.</h3></div>
2104    
2105    <div class="section" id="no-attr-namespace-separator"><h3>Attribute namespace wildcard <code>*</code>
2106      is not followed by a <code>|</code> character.</h3></div>
2107    
2108    <div class="section" id="no-attr-value"><h3>Attribute value is missing.</h3></div>
2109    
2110    <div class="section" id="no-class-name-selector"><h3>Class name is missing.</h3></div>
2111    
2112    <div class="section" id="no-combinator"><h3>Combinator is missing.</h3></div>
2113    
2114    <div class="section" id="no-contains-string"><h3>No string is specified in the argument
2115      list of the <code>:-manakai-contains</code> pseudo-class
2116      selector.</h3></div>
2117    
2118    <div class="section" id="no-lang-tag"><h3>Language tag argument is missing.</h3></div>
2119    
2120    <div class="section" id="no-local-name-selector"><h3>Local name part of the type selector (or
2121      <code>*</code> for the universal selector) is missing.</h3></div>
2122    
2123    <div class="section" id="no-pseudo-class-name"><h3>Pseudo-class name is missing.</h3></div>
2124    
2125    <div class="section" id="no-pseudo-element-name"><h3>Pseudo-element name is missing.</h3></div>
2126    
2127    <div class="section" id="no-sss"><h3>Sequence of simple selectors is
2128      expected.</h3></div>
2129    
2130    <div class="section" id="not-not-closed"><h3>Argument list of the <code>:not</code> selector
2131      is not closed by a <code>)</code> character.</h3></div>
2132    
2133    <div class="section" id="ss-after-pseudo-element"><h3>Simple selector is not allowed after a
2134      pseudo element.</h3></div>
2135    
2136    <div class="section" id="unknown-pseudo-class"><h3>Pseudo-class <code>:<var>{value}</var></code>
2137      is not supported by the conformance checker.</h3></div>
2138    
2139    <div class="section" id="unknown-pseudo-element"><h3>Pseudo-element <code>::<var>{value}</var></code>
2140      is not supported by the conformance checker.</h3></div>
2141    
2142    </section>
2143    
2144    <section id="css-errors">
2145    <h2>CSS Errors</h2>
2146    
2147    <div class="section" id="at-rule-not-allowed"><h3>An <code>@<var>{text}</var></code> rule is not
2148      allowed here.</h3></div>
2149    
2150    <div class="section" id="at-rule-syntax-error"><h3>The <code>@<var>{text}</var></code> rule is
2151      syntactically incorrect.</h3></div>
2152    
2153    <div class="section" id="block-not-closed"><h3>Block is not closed before the end of
2154      file.</h3></div>
2155    
2156    <div class="section" id="CSS-duplication"><h3>Component <code>&lt;<var>{text}</var>&gt;</code> is
2157      already specified.</h3></div>
2158    
2159    <div class="section" id="CSS-cursor-hand"><h3>Value <code>hand</code> is not valid as
2160      <code>&lt;'cursor'&gt;</code>.</h3></div>
2161    
2162    <div class="section" id="CSS-syntax-error"><h3>Specified value is syntactically not a correct
2163      <code>&lt;<var>{text}</var>&gt;</code>.</h3></div>
2164    
2165    <div class="section" id="no-declaration-block"><h3>No declaration block is found after a group of
2166      selectors.</h3></div>
2167    
2168    <div class="section" id="no-property-colon"><h3>A <code>:</code> character is missing after
2169      a property name.</h3></div>
2170    
2171    <div class="section" id="no-property-name"><h3>Property name is expected.</h3></div>
2172    
2173    <div class="section" id="no-property-semicolon"><h3>A <code>;</code> character is missing at the
2174      end of the property.</h3></div>
2175    
2176    <div class="section" id="priority-syntax-error"><h3>Priority part of the declaration is syntactically
2177      incorrect.</h3></div>
2178    
2179    <div class="section" id="unknown-at-rule"><h3>The <code>@<var>{value}</var></code> rule is
2180      not supported by the conformance checker.</h3></div>
2181    
2182    <div class="section" id="unknown-property"><h3>Property <code><var>{value}</var></code> is
2183      not supported by the conformance checker.</h3></div>
2184    
2185    </section>
2186    
2187    <section id="cache-manifest-errors">
2188    <h2>Cache Manifest Errors</h2>
2189    
2190    <div class="section" id="both-in-entries-and-whitelist"><h3>This URL is found both in the explicit or
2191      fallback entries and in the online whitelist.</h3></div>
2192    
2193    <div class="section" id="different-origin-from-manifest"><h3>The specified URL has different origin from
2194      the manifest.</h3></div>
2195    
2196    <div class="section" id="different-scheme-from-manifest"><h3>The scheme component of the URL is
2197      different from that of the manifest URL.  The URL is ignored.</h3></div>
2198    
2199    <div class="section" id="duplicate-oc-namespace"><h3>This oppotunistic caching namespace is already
2200      specified.</h3></div>
2201    
2202    <div class="section" id="no-fallback-entry-URL"><h3>Fallback entry URL is missing.</h3></div>
2203    
2204    <div class="section" id="not-manifest"><h3>This document is not a cache manifest.</h3>
2205        <p>The specified document is <em>not</em> a cache manifest.
2206        The document is non-conforming.</p>
2207    
2208        <p>An entity labeled as Internet media type
2209        <code>text/cache-manifest</code> must contain a cache manifest.</p>
2210    
2211        <p>A cache manifest must start with a line whose content is
2212        <code class="manifest example">CACHE MANIFEST</code>
2213        (exactly one space character between
2214        <code>CACHE</code> and <code>MANIFEST</code>).</p>
2215      </div>
2216    
2217    <div class="section" id="same-as-manifest-URL"><h3>This URL is same as the manifest URL.</h3></div>
2218    
2219    </section>
2220    
2221    <section id="regexp-errors">
2222    <h2>Regular Expression Errors</h2>
2223    
2224    <!-- Errors in this section are sorted by
2225    Regexp::Parser::Diagnostics's order, then followed by the
2226    Regexp::Parser::JavaScript's extension. -->
2227    
2228    <!-- TODO: mark fatal errors as such -->
2229    
2230    <div class="section" id="Quantifier-unexpected-on-zero-length-expression"><h3>Quantifier unexpected on zero-length
2231      expression.</h3></div>
2232    
2233    <div class="section" id="Sequence-(?%.*s...)-not-implemented"><h3>Sequence
2234      <code>(?<var>{text}</var><var>...</var>)</code> is not implemented
2235      by Perl.</h3></div>
2236    
2237    <div class="section" id="Sequence-(?#...-not-terminated"><h3>Sequence <code>(?#<var>...</var></code> is
2238      not terminated by <code>)</code>.</h3></div>
2239    
2240    <div class="section" id="(?p{})-is-deprecated----use-(??{})"><h3><code>(?p{<var>...</var>})</code> is
2241      obsolete.</h3>
2242        <p><code>(?p{})</code> is obsolete.  It was deprecated in
2243        Perl 5.8 and is <em>no longer supported</em> in Perl 5.10.</p>
2244    
2245        <p>You can use <code>(??{<var>...</var>})</code> instead.</p>
2246      </div>
2247    
2248    <div class="section" id="Sequence-(?{...})-not-terminated-or-not-{}-balanced"><h3>Sequence <code>(?{<var>...</var>})</code>
2249      is not terminated or <code>{<var>...</var>}</code> is not
2250      balanced.</h3></div>
2251    
2252    <div class="section" id="Switch-condition-not-recognized"><h3>Switch condition is not recognized.</h3></div>
2253    
2254    <div class="section" id="Switch-(?(condition)...-contains-too-many-branches"><h3>Switch
2255      <code>(?(<var>condition</var>)<var>...</var>|<var>...</var><mark>|...</mark>)</code>
2256      contains too many branches.</h3></div>
2257    
2258    <div class="section" id="Unknown-switch-condition-(?(%.2s"><h3>An unknown switch condition
2259      <code>(?(<var>{text}</var></code> is used.</h3></div>
2260    
2261    <div class="section" id="Sequence-(?-incomplete"><h3>Sequence <code>(?<var>...</var></code> is
2262      incomplete.</h3></div>
2263    
2264    <div class="section" id="Useless-(?%s%s)----%suse-/%s-modifier"><h3>Modifier <code>(?<var>{text}</var>)</code>
2265      <em>in</em> a regular expression has no effect.</h3></div>
2266    
2267    <div class="section" id="Sequence-(?%.*s...)-not-recognized"><h3>An unknown sequence
2268      <code>(?<var>{text}</var><var>...</var>)</code> is used.</h3></div>
2269    
2270    <div class="section" id="Unmatched-("><h3>A <code>(<var>...</var></code> sequence
2271      is not terminated by <code>)</code>.</h3></div>
2272    
2273    <div class="section" id="Unmatched-)"><h3>An unmatched <code>)</code> is found.</h3></div>
2274    
2275    <div class="section" id="Can't-do-{n,m}-with-n-&gt;-m"><h3>Quantifier <code>{<var>n</var>,<var>m</var>}</code>
2276      cannot be <span class="math"><var>n</var> &gt; <var>m</var></span>.</h3></div>
2277    
2278    <div class="section" id="%s-matches-null-string-many-times"><h3><code><var>{text}</var></code> matches
2279      the empty string too many times.</h3></div>
2280    
2281    <div class="section" id="Nested-quantifiers"><h3>Quantifiers cannot be nested.</h3></div>
2282    
2283    <div class="section" id="Unmatched-["><h3>A character class <code>[<var>...</var></code>
2284      is not terminated by <code>]</code>.</h3></div>
2285    
2286    <div class="section" id="Quantifier-follows-nothing"><h3>Quantifier follows nothing.</h3></div>
2287    
2288    <div class="section" id="Missing-braces-on-\%s{}"><h3>A <code>\<var>{text}</var></code> sequence
2289      is not followed by <code>{<var>...</var>}</code>.</h3></div>
2290    
2291    <div class="section" id="Missing-right-brace-on-\%s{}"><h3>A <code>\<var>{text}</var>{<var>...</var></code>
2292      is not terminated by <code>}</code>.</h3></div>
2293    
2294    <div class="section" id="Reference-to-nonexistent-group"><h3>A nonexistent group is referenced.</h3></div>
2295    
2296    <div class="section" id="Trailing-\"><h3>A <code>\</code> character is not followed by
2297      another character,</h3></div>
2298    
2299    <div class="section" id="Unrecognized-escape-\%s-passed-through"><h3>An unknown escape <code>\<var>{text}</var></code>
2300      is used.</h3></div>
2301    
2302    <div class="section" id="Unrecognized-escape-\%s-in-character-class-passed-through"><h3>An unknown escape <code>\<var>{text}</var></code>
2303      is used in a character class.</h3></div>
2304    
2305    <div class="section" id="POSIX-class-[:%s:]-unknown"><h3>An unknown POSIX character class
2306      <code>[:<var>{text}</var>:]</code> is used.</h3></div>
2307    
2308    <div class="section" id="POSIX-syntax-[%s-%s]-belongs-inside-character-classes"><h3>A POSIX syntax
2309      <code>[<var>{text}</var><var>...</var><var>{text}</var>]</code> is used
2310      outside of character classes.</h3></div>
2311    
2312    <div class="section" id="Empty-\%s{}"><h3>An escape <code>\<var>{text}</var>{}</code>
2313      is empty.</h3></div>
2314    
2315    <div class="section" id="False-[]-range-&quot;%s-%s&quot;"><h3>An escape that represents a character
2316      class cannot be used in range <code><var>{text}</var></code>.</h3></div>
2317    
2318    <div class="section" id="Invalid-[]-range-&quot;%s-%s&quot;"><h3>Character range <code><var>{text}</var></code>
2319      is invalid.</h3></div>
2320    
2321    <div class="section" id="Octal-escape-is-obsolete"><h3>Octal escape is used.</h3></div>
2322    
2323    </section>
2324    
2325    <section id="webidl-errors">
2326    <h2>WebIDL Errors</h2>
2327    
2328    <div class="section" id="after-argument"><h3>An argument name is not followed by a
2329      <code>,</code> character or a <code>)</code> character.</h3></div>
2330    
2331    <div class="section" id="after-exception-name"><h3>An exception name is not followed by a
2332      <code>,</code> character or a <code>)</code> character.</h3></div>
2333    
2334    <div class="section" id="after-unsigned"><h3>キーワード <code>unsigned</code> の後の字句が
2335      <code>short</code> か <code>long</code> ではありません。</h3></div>
2336    
2337    <div class="section" id="after-xattr"><h3>An extended attribute is not followed by
2338      a <code>,</code> character or a <code>]</code> character.</h3></div>
2339    
2340    <div class="section" id="argument-after-variadic"><h3>An argument is specified after an argument
2341      with <code>Variadic</code> extended attribute is seen.</h3></div>
2342    
2343    <div class="section" id="attr-not-readonly"><h3>Extended attribute <code><var>{text}</var></code> is
2344      specified for an attribute that is not read-only.</h3></div>
2345    
2346    <div class="section" id="attr-type-not-interface"><h3>Extended attribute <code><var>{text}</var></code>
2347      is specified for an attribute whose type is not an interface.</h3></div>
2348    
2349    <div class="section" id="before-exception-member"><h3>An unknown construct is found where an exception
2350      member or a <code>}</code> character is expected.</h3></div>
2351    
2352    <div class="section" id="before-interface-member"><h3>An unknown construct is found where an interface
2353      member or a <code>}</code> character is expected.</h3></div>
2354    
2355    <div class="section" id="before-webidl-block"><h3>An identifier for the <code><var>{text}</var></code>
2356      is not followed by a <code>{</code> character.</h3></div>
2357    
2358    <div class="section" id="before-webidl-def"><h3>An unknown construct is found after an
2359      extended attribute list (where a <code>Definition</code> is
2360      expected).</h3></div>
2361    
2362    <div class="section" id="before-webidl-defs"><h3>An unknown construct is found where a
2363      <code>Definition</code> (optionally preceded by an extended attribute list)
2364      is expected.</h3></div>
2365    
2366    <div class="section" id="before-webidl-type"><h3>The type for <code><var>{text}</var></code> is
2367      not specified.</h3></div>
2368    
2369    <div class="section" id="before-webidl-type:argument"><h3>The type for an argument is not
2370      specified.</h3></div>
2371    
2372    <div class="section" id="before-webidl-type:exception-member"><h3>The type for an exception member is not
2373      specified.</h3></div>
2374    
2375    <div class="section" id="before-xattr"><h3>No extended attribute is specified after
2376      a <code>[</code> character.</h3></div>
2377    
2378    <div class="section" id="before-xattrarg"><h3>No identifier is specified in an extended
2379      attribute assignment.</h3></div>
2380    
2381    <div class="section" id="const-value-out-of-range"><h3>The specified value <code><var>{value}</var></code>
2382      is outside of the range of the type for the constant,
2383      <code><var>{text}</var></code>.</h3></div>
2384    
2385    <div class="section" id="const-type-mismatch"><h3>The type of the value,
2386      <code><var>{value}</var></code>, is different from the type of the constant,
2387      <code><var>{text}</var></code>.</h3></div>
2388    
2389    <div class="section" id="duplicate-accessor"><h3>Extended attribute <code><var>{text}</var></code>
2390      is already specified for another operation in the same interface.</h3></div>
2391    
2392    <div class="section" id="duplicate-constructor-name"><h3>Constructor name <code><var>{value}</var></code>
2393      specified by extended attribute <code><var>{text}</var></code> is already
2394      used for an interface.</h3></div>
2395    
2396    <div class="section" id="duplicate-member"><h3>Name <code><var>{text}</var></code> is
2397      already used.</h3></div>
2398    
2399    <div class="section" id="duplicate-qname"><h3>Qualified name <code><var>{text}</var></code> is
2400      already used.</h3></div>
2401    
2402    <div class="section" id="duplicate-xattr"><h3>Extended attribute <code><var>{text}</var></code>
2403      is already specified.</h3></div>
2404    
2405    <div class="section" id="exception-not-defined"><h3>Exception <code><var>{text}</var></code> is
2406      not defined in the fragment.</h3></div>
2407    
2408    <div class="section" id="interface-not-defined"><h3>Interface <code><var>{text}</var></code> is
2409      not defined in the fragment.</h3></div>
2410    
2411    <div class="section" id="no-arguments-in"><h3>No <code>in</code> keyword for an argument is
2412      found.</h3></div>
2413    
2414    <div class="section" id="no-arguments-lparen"><h3>No <code>(</code> character for an argument
2415      list is found.</h3></div>
2416    
2417    <div class="section" id="no-raises-lparen"><h3>A <code>raises</code> (or <code>getraises</code>
2418      or <code>setraises</code>) keyword is not followed by a <code>(</code>
2419      character.</h3></div>
2420    
2421    <div class="section" id="no-sequence-gt"><h3>A <code>sequence&lt;&gt;</code> type is not
2422      terminated by a <code>&gt;</code> character.</h3></div>
2423    
2424    <div class="section" id="no-sequence-lt"><h3>Keyword <code>sequence</code> is not followed
2425      by a <code>&lt;</code> character.</h3></div>
2426    
2427    <div class="section" id="no-sequence-type"><h3>No type is specified in
2428      <code>sequence&lt;&gt;</code>.</h3></div>
2429    
2430    <div class="section" id="no-webidl-identifier"><h3>No identifier is specified for the
2431      <code><var>{text}</var></code>.</h3></div>
2432    
2433    <div class="section" id="no-webidl-identifier:argument"><h3>No identifier is specified for the
2434      argument.</h3></div>
2435    
2436    <div class="section" id="no-webidl-identifier:exception-member"><h3>No identifier is specified for the
2437      exception member.</h3></div>
2438    
2439    <div class="section" id="no-webidl-identifier:operation"><h3>No identifier is specified for the
2440      operation.</h3></div>
2441    
2442    <div class="section" id="no-webidl-semicolon"><h3>No semicolon is found at the end of the
2443      definition or member.</h3></div>
2444    
2445    <div class="section" id="non-module-definition"><h3>This definition is not part of any
2446      module.</h3></div>
2447    
2448    <div class="section" id="not-boxable-type"><h3>Type <code><var>{text}</var></code> cannot be
2449      used in <code>valuetype</code>.</h3></div>
2450    
2451    <div class="section" id="premature-end-of-webidl"><h3>The WebIDL fragment ends before all the blocks
2452      are closed by <code>};</code> sequences.</h3></div>
2453    
2454    <div class="section" id="referenced-attr-not-defined"><h3>Attribute <code><var>{value}</var></code> is
2455      not defined in the interface specified for the attribute to which
2456      extended attribute <code><var>{text}</var></code> is set.</h3></div>
2457    
2458    <div class="section" id="scoped-name"><h3>A scoped name is expected here.</h3></div>
2459    
2460    <div class="section" id="scoped-name:dcolon"><h3>A <code>::</code> token is not followed by
2461      an identifier or a <code>DOMString</code> keyword.</h3></div>
2462    
2463    <div class="section" id="type-not-defined"><h3>Type <code><var>{text}</var></code> is not
2464      defined.</h3></div>
2465    
2466    <div class="section" id="typedef-ignored"><h3><code>typedef</code> of name <code>DOMString</code>
2467      is ignored.</h3></div>
2468    
2469    <div class="section" id="unknown-xattr"><h3>An unknown extended attribute
2470      <code><var>{text}</var></code> is used.</h3></div>
2471    
2472    <div class="section" id="valuetype-DOMString"><h3>The <code>valuetype</code> definition does
2473      not define <code>DOMString</code> as
2474      <code>sequence&lt;unsigned short&gt;</code>.</h3></div>
2475    
2476    <div class="section" id="valuetype-ignored"><h3><code>valuetype</code> of name
2477      <code>DOMString</code> is ignored.</h3></div>
2478    
2479    <div class="section" id="wrong-signature-accessor"><h3>The operation cannot be used as accessor operation
2480      of <code><var>{text}</var></code>, since its signature different from
2481      the expected one.</h3></div>
2482    
2483    <div class="section" id="xattr-arglist-not-allowed"><h3>Use of an argument list for extended attribute
2484      <code><var>{text}</var></code> is not allowed.</h3></div>
2485    
2486    <div class="section" id="xattr-for-wrong-type"><h3>Extended attribute <code><var>{text}</var></code>
2487      is not applicable for an attribute whose type is not
2488      <code>DOMString</code>.</h3></div>
2489    
2490    <div class="section" id="xattr-id-missing"><h3>The identifier for extended attribute
2491      <code><var>{text}</var></code> is not specified.</h3></div>
2492    
2493    <div class="section" id="xattr-id-not-allowed"><h3>Use of an identifier for extended attribute
2494      <code><var>{text}</var></code> is not allowed.</h3></div>
2495    
2496    <div class="section" id="xattr-id-value-not-allowed"><h3>The identifier <code><var>{value}</var></code> is
2497      not an allowed value for extended attribute
2498      <code><var>{text}</var></code>.</h3></div>
2499    
2500    <div class="section" id="xattr-not-applicable"><h3>Extended attribute <code><var>{text}</var></code>
2501      is not applicable to this kind of object.</h3></div>
2502    
2503    </section>
2504    
2505    <section id="information">
2506    <h2>Stability Information</h2>
2507    
2508    <div class="section" id="deprecated:attr"><h3>This attribute is deprecated.</h3></div>
2509    
2510    <div class="section" id="deprecated:element"><h3>This element is deprecated.</h3></div>
2511    
2512    <div class="section" id="status:cr:element"><h3>This element is in the
2513      <strong>call for implementation</strong> stage.</h3>
2514        <p>The element is in the call for implementation stage.</p>
2515        
2516        <p>Usually, using the element is safe.  However, it is a new feature
2517        so that it might not be implemented correctly.  If it is found that
2518        the feature is hard or impossible to implement, the feature
2519        might be revised, or in some case it might be dropped.</p>
2520    
2521        <p>Elements defined by Atom 1.0 (IETF Proposed Standard), and XBL 2.0
2522        (W3C Candidate Recommendation) belong to this class.</p>
2523      </div>
2524    
2525    <div class="section" id="status:lc:element"><h3>This element is in the <strong>last
2526      call for comments</strong> stage.</h3>
2527        <p>The element is in the last call for comments stage.</p>
2528        
2529        <p>The element is relatively mature, though the standardization
2530        is not done yet.  It may be used for experiments.  Since it is a new
2531        feature, it might not be implemented correctly or at all.  If it is
2532        found that the feature is hard or impossible to implement, the feature
2533        might be revised or might be dropped.</p>
2534    
2535        <p>Elements defined by Web Forms 2.0 as well as some elements
2536        defined by HTML5 belong to this class.</p>
2537      </div>
2538    
2539    <div class="section" id="status:wd:element"><h3>This element is documented in a <strong>working
2540      draft</strong>.</h3>
2541        <p>The element is documented in a working or editor's draft
2542        and not yet completed.</p>
2543        
2544        <p>The element should not be used for any practical purpose.
2545        The feature might be drastically changed later or might be
2546        entirely removed.</p>
2547    
2548        <p>Most of new elements defined by HTML5 belong to this class.</p>
2549      </div>
2550    
2551    <div class="section" id="status:non-standard:element"><h3>This element is <strong>not part of any
2552      standard</strong> the conformance checker knows.</h3>
2553        <p>The element is not part of any standard or draft the conformance
2554        checker is aware of.</p>
2555        
2556        <p>The element should not be used for any practical purpose unless
2557        there is really a standard that defines the element.</p>
2558      </div>
2559    
2560    <div class="section" id="status:cr:attr"><h3>This attribute is in the
2561      <strong>call for implementation</strong> stage.</h3>
2562        <p>The attribute is in the call for implementation stage.</p>
2563        
2564        <p>Usually, using the attribute is safe.  However, it is a new feature
2565        so that it might not be implemented correctly.  If it is found that
2566        the feature is hard or impossible to implement, the feature
2567        might be revised, or in some case it might be dropped.</p>
2568      </div>
2569    
2570    <div class="section" id="status:lc:attr"><h3>This attribute is in the <strong>last
2571      call for comments</strong> stage.</h3>
2572        <p>The attribute is in the last call for comments stage.</p>
2573        
2574        <p>The attribute is relatively mature, though the standardization
2575        is not done yet.  It may be used for experiments.  Since it is a new
2576        feature, it might not be implemented correctly or at all.  If it is
2577        found that the feature is hard or impossible to implement, the feature
2578        might be revised or might be dropped.</p>
2579      </div>
2580    
2581    <div class="section" id="status:wd:attr"><h3>This attribute is documented in a <strong>working
2582      draft</strong>.</h3>
2583        <p>The attribute is documented in a working or editor's draft
2584        and not yet completed.</p>
2585        
2586        <p>The attribute should not be used for any practical purpose.
2587        The feature might be drastically changed later or might be
2588        entirely removed.</p>
2589      </div>
2590    
2591    <div class="section" id="status:non-standard:attr"><h3>This attribute is <strong>not part of any
2592      standard</strong> the conformance checker knows.</h3>
2593        <p>The attribute is not part of any standard or draft the conformance
2594        checker is aware of.</p>
2595        
2596        <p>The attribute should not be used for any practical purpose unless
2597        there is really a standard that defines the attribute.</p>
2598      </div>
2599    </section>
2600    
2601    <section id="langtag-errors">
2602    <h2>Language Tag Errors</h2>
2603    
2604    <div class="section" id="langtag:extension:duplication"><h3>There is another extension subtag
2605      <code><var>{value}</var></code>.</h3></div>
2606    
2607    <div class="section" id="langtag:extension:order"><h3>Extension subtag <code><var>{value}</var></code>
2608      is placed after subtag <code><var>{text}</var></code>.</h3></div>
2609    
2610    <div class="section" id="langtag:extension:unknown"><h3>Extension <code><var>{value}</var></code> is not
2611      defined when the conformance checker is written.</h3></div>
2612    
2613    <div class="section" id="langtag:extlang:case"><h3>Extended language subtag
2614      <code><var>{value}</var></code> is not in the preferred form, i.e. in
2615      lowercase.</h3></div>
2616    
2617    <div class="section" id="langtag:extlang:deprecated"><h3>Use of extended language subtag
2618      <code><var>{value}</var></code> is deprecated<!-- in favor of {text} (might
2619      be undef) -->.</h3></div>
2620    
2621    <div class="section" id="langtag:extlang:prefix"><h3>Extended language subtag
2622      <code><var>{text}</var></code> is not allowed in the combination with this
2623      language (and extended language) subtag(s).</h3></div>
2624    
2625    <div class="section" id="langtag:extlang:invalid"><h3>Extended language subtag
2626      <code><var>{text}</var></code> is not registered.</h3></div>
2627    
2628    <div class="section" id="langtag:grandfathered:case"><h3>Language tag <code><var>{value}</var></code> is
2629      not in the preferred case combination.</h3></div>
2630    
2631    <div class="section" id="langtag:grandfathered:deprecated"><h3>Use of language tag
2632      <code><var>{value}</var></code> is deprecated<!-- in favor of {text} (might
2633      be undef) -->.</h3></div>
2634    
2635    <div class="section" id="langtag:grandfathered:invalid"><h3>Language tag <code><var>{value}</var></code> is
2636      not a combination of RFC 4646 subtags and is not a registered grandfathered
2637      tag.</h3></div>
2638    
2639    <div class="section" id="langtag:illegal"><h3>Subtag <code><var>{value}</var></code> is
2640      syntactically invalid.</h3></div>
2641    
2642    <div class="section" id="langtag:language:case"><h3>It is a good practice to represent ISO 639-1
2643      language code <code><var>{value}</var></code> in lowercase.</h3></div>
2644    
2645    <div class="section" id="langtag:language:deprecated"><h3>Use of language subtag
2646      <code><var>{value}</var></code> is deprecated<!-- in favor of {text} (might
2647      be undef) -->.</h3></div>
2648    
2649    <div class="section" id="langtag:language:invalid"><h3>Language subtag <code><var>{value}</var></code>
2650      is not registered.</h3></div>
2651    
2652    <div class="section" id="langtag:language:mul"><h3>Langauge tag <code>mul</code> should not be
2653      used.</h3></div>
2654    
2655    <div class="section" id="langtag:language:nosemantics"><h3>No semantics is defined for language subtag
2656      <code><var>{value}</var></code>.</h3></div>
2657    
2658    <div class="section" id="langtag:language:private"><h3>Language subtag <code><var>{value}</var></code>
2659      is a private use code.</h3></div>
2660    
2661    <div class="section" id="langtag:language:syntax"><h3>The language subtag <code><var>{value}</var></code>
2662      is syntactically invalid.</h3></div>
2663    
2664    <div class="section" id="langtag:language:und"><h3>Langauge tag <code>und</code> should not be
2665      used.</h3></div>
2666    
2667    <div class="section" id="langtag:private"><h3>It would be better if a private use language
2668      tag (<code><var>{value}</var></code>) is not used.</h3></div>
2669    
2670    <div class="section" id="langtag:privateuse"><h3>Private use subtag <code><var>{value}</var></code>
2671      is used.</h3></div>
2672    
2673    <div class="section" id="langtag:privateuse:case"><h3>Subtag <code><var>{value}</var></code> is not
2674      represented in the preferred case format.</h3></div>
2675    
2676    <div class="section" id="langtag:privateuse:syntax"><h3>Private use subtag <code><var>{value}</var></code>
2677      is syntactically invalid.</h3></div>
2678    
2679    <div class="section" id="langtag:redundant:case"><h3>Language tag <code><var>{value}</var></code> is
2680      not in the preferred case combination.</h3></div>
2681    
2682    <div class="section" id="langtag:redundant:deprecated"><h3>Use of language tag
2683      <code><var>{value}</var></code> is deprecated<!-- in favor of {text} (might
2684      be undef) -->.</h3></div>
2685    
2686    <div class="section" id="langtag:region:case"><h3>It is a good practice to represent ISO 3166
2687      country code <code><var>{value}</var></code> in uppercase.</h3></div>
2688    
2689    <div class="section" id="langtag:region:deprecated"><h3>Use of region subtag
2690      <code><var>{value}</var></code> is deprecated<!-- in favor of {text} (might
2691      be undef) -->.</h3></div>
2692    
2693    <div class="section" id="langtag:region:nosemantics"><h3>No semantics is defined for region subtag
2694      <code><var>{value}</var></code>.</h3></div>
2695    
2696    <div class="section" id="langtag:region:invalid"><h3>Region subtag <code><var>{value}</var></code>
2697      is not registered.</h3></div>
2698    
2699    <div class="section" id="langtag:region:private"><h3>Use of private use country code
2700      <code><var>{value}</var></code> is not allowed.</h3></div>
2701    
2702    <div class="section" id="langtag:script:case"><h3>Script subtag <code><var>{value}</var></code> is
2703      not in the preferred form, i.e. titlecase.</h3></div>
2704    
2705    <div class="section" id="langtag:script:deprecated"><h3>Use of script subtag
2706      <code><var>{value}</var></code> is deprecated<!-- in favor of {text} (might
2707      be undef) -->.</h3></div>
2708    
2709    <div class="section" id="langtag:script:invalid"><h3>Script subtag <code><var>{value}</var></code>
2710      is not registered.</h3></div>
2711    
2712    <div class="section" id="langtag:script:private"><h3>Script subtag <code><var>{value}</var></code>
2713      is a private use code.</h3></div>
2714    
2715    <div class="section" id="langtag:script:suppress"><h3>Script subtag <code><var>{value}</var></code>
2716      should be suppressed when the language subtag is
2717      <code><var>{text}</var></code>.</h3></div>
2718    
2719    <div class="section" id="langtag:variant:case"><h3>Variant subtag <code><var>{value}</var></code> is
2720      not in the preferred form, i.e. lowercase.</h3></div>
2721    
2722    <div class="section" id="langtag:variant:combination"><h3>Variant subtag <code><var>{text}</var></code> might
2723      not be meaningful when it is used in combination with
2724      <code><var>{value}</var></code>.</h3></div>
2725    
2726    <div class="section" id="langtag:variant:deprecated"><h3>Use of variant subtag
2727      <code><var>{value}</var></code> is deprecated<!-- in favor of {text} (might
2728      be undef) -->.</h3></div>
2729    
2730    <div class="section" id="langtag:variant:duplication"><h3>Variant subtag <code><var>{value}</var></code>
2731      is specified twice.</h3></div>
2732    
2733    <div class="section" id="langtag:variant:invalid"><h3>Variant subtag <code><var>{value}</var></code>
2734      is not registered.</h3></div>
2735    
2736    <div class="section" id="langtag:variant:prefix"><h3>Variant subtag <code><var>{value}</var></code>
2737      cannot be used in this context.</h3></div>
2738    
2739    </section>
2740    
2741    <section id="rdfxml-errors">
2742    <h2>RDF/XML Errors</h2>
2743    
2744    <div class="section" id="bad-rdf-namespace"><h3>The namespace URI of an element that
2745      represents an RDF concept must be
2746      <code>http://www.w3.org/1999/02/22-rdf-syntax-ns#</code>.</h3></div>
2747    
2748    <div class="section" id="duplicate-rdf-id"><h3>The specified value is already used as an
2749      ID.</h3></div>
2750    
2751    <div class="section" id="duplicate-unqualified-attr"><h3>Both unqualified attribute and namespace‐qualified
2752      RDF attribute are specified, which is not allowed.</h3></div>
2753    
2754    <div class="section" id="parse-type-other"><h3>An invalid value is specified to
2755      the <code>parseType</code> attribute.</h3></div>
2756    
2757    <div class="section" id="second-node-element"><h3>There is another element, such that
2758      this element is not allowed.</h3></div>
2759    
2760    <div class="section" id="unqualified-attr"><h3>Unqualified attribute is not allowed.</h3></div>
2761    
2762    <div class="section" id="unqualified-rdf-attr"><h3>RDF attribute should be
2763      namespace‐qualified.</h3></div>
2764    
2765  </section>  </section>
2766    
2767  <section id="unsupported-messages">  <section id="unsupported-messages">
2768  <h2><i>Unsupported</i> Messages</h2>  <h2><i>Unsupported</i> Messages</h2>
2769    
2770  <div class="section unsupported" id="unsupported:attribute"><h3>This attribute is not supported by the  <div class="section" id="unknown-element"><h3>Conformance checking for element
2771    conformance checker; <em>it might or might not be conforming</em>.</h3>    <code><var>{local-name}</var></code> is not supported; <em>it might or
2772      <p>The conformant checker does not support the attribute.    might not be conforming</em>.</h3>
2773        <p>The conformant checker does not support the element.
2774      It cannot determine whether the document is conforming or not.</p>      It cannot determine whether the document is conforming or not.</p>
2775    </div>    </div>
2776    
2777  <div class="section unsupported" id="unsupported:element"><h3>This element is not supported by the  <div class="section" id="unknown-attribute"><h3>Conformance checking for attribute
2778    conformance checker; <em>it might or might not be conforming</em>.</h3>    <code><var>{local-name}</var></code> of element
2779      <p>The conformant checker does not support the element.    <code><var>{element-local-name}</var></code> is not supported;
2780      <em>it might or might not be conforming</em>.</h3>
2781        <p>The conformant checker does not support the attribute.
2782      It cannot determine whether the document is conforming or not.</p>      It cannot determine whether the document is conforming or not.</p>
2783    </div>    </div>
2784    
2785  <div class="section unsupported" id="unsupported:link-type"><h3>The link type <code>$0</code> is not standardized  <div class="section" id="unknown-link-type"><h3>Link type <code><var>{value}</var></code> is not
2786    or registered at the time of the release of the conformance checker;    standardized or registered at the time of the release of the conformance
2787    <em>it is non-conforming unless it has now been registered</em>.</h3>    checker; <em>it is non-conforming unless it now has been
2788      registered</em>.</h3>
2789      <p>The <code>rel</code> attribute is defined as a list of link types.      <p>The <code>rel</code> attribute is defined as a list of link types.
2790      Some common link types are defined in the HTML5 specification.      Some common link types are defined in the HTML5 specification.
2791      Additional link types can be registered to the WHATWG Wiki.      Additional link types can be registered to the WHATWG Wiki.
# Line 471  Web Document Conformance Checker (BETA)< Line 2796  Web Document Conformance Checker (BETA)<
2796      The link type might have been added to the registry since then.      The link type might have been added to the registry since then.
2797      In such case it might be conforming.  Otherwise, the      In such case it might be conforming.  Otherwise, the
2798      document is non-conforming.</p>      document is non-conforming.</p>
2799    
2800        <dl>
2801        <dt>Link types <code>shortcut icon</code></dt>
2802            <dd>Link type <code>shortcut</code> is not registered.
2803            Use only <code>icon</code> for linking to so-called favicon.</dd>
2804        </dl>
2805      </div>
2806    
2807    <div class="section" id="event-handler"><h3>Conformance checking for event handler attribute
2808      is not supported; <em>it might or might not be conforming.</em></h3></div>
2809    
2810    <div class="section" id="media-query"><h3>Conformance checking for media query
2811      is not supported; <em>it might or might not be conforming.</em></h3></div>
2812    
2813    <div class="section" id="addr-spec-not-supported"><h3>Conformance checking for an <code>addr-spec</code>
2814      is not supported; <em>it might or might not be conforming.</em></h3></div>
2815    
2816    <div class="section" id="XML-script-lang"><h3>Conformance checking for script
2817      language <code><var>{text}</var></code> is not supported;
2818      <em>it might or might not be conforming.</em></h3></div>
2819    
2820    <div class="section" id="XML-style-lang"><h3>Conformance checking for style
2821      language <code><var>{text}</var></code> is not supported;
2822      <em>it might or might not be conforming.</em></h3></div>
2823    
2824    <div class="section" id="atom|content-not-supported"><h3>Conformance checking for an Atom
2825      <code>content</code> element with <code>type</code>
2826      <code><var>{text}</var></code> is not supported.</h3></div>
2827    
2828    <div class="section" id="help-not-available"><h3>No more information is available.</h3>
2829        <p>No more information is available for this topic.</p>
2830    </div>    </div>
2831    
2832  </section>  </section>
2833    
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3040    
3041    
3042    <div class="section" id="Error-level-m"><h3><a href="../error-description#Error-level-m" rel="help"><em class="rfc2119">MUST</em>‐level
3043            error</a></h3>
3044        <p>A violation to a hard requirement of the specification.
3045        The document is non‐conforming.</p>
3046      </div>
3047    
3048    <div class="section" id="Error-level-s"><h3><a href="../error-description#Error-level-s" rel="help"><em class="rfc2119">SHOULD</em>‐level
3049            error</a></h3>
3050        <p>A violation to a requirement of the specification.
3051        The violation might be legitimize in some case.  Otherwise,
3052        the document is non‐conforming.</p>
3053      </div>
3054    
3055    <div class="section" id="Error-level-w"><h3><a href="../error-description#Error-level-w" rel="help">Warning</a></h3>
3056        <p>A warning is an advice from the conformance checker
3057        to avoid solving a problem in a confusing or possibly wrong way.
3058        It does not affect to the conformance of the document, and
3059        may sometimes be inappropriate.</p>
3060      </div>
3061    
3062    <div class="section" id="Error-level-i"><h3><a href="../error-description#Error-level-i" rel="help">Information</a></h3>
3063        <p>An informational message just provides an additional information
3064        on the feature used in the document or the status of the retrieval
3065        or so on.
3066        It does not affect to the conformance of the document.</p>
3067      </div>
3068    
3069    <div class="section" id="Error-level-u"><h3><a href="../error-description#Error-level-u" rel="help">Not
3070          supported</a></h3>
3071        <p>Some feature that is not supported by the conformance checker
3072        is used in the document.</p>
3073      </div>
3074    
3075  <section id="license">  <section id="license">
3076  <h2>License of This Document</h2>  <h2>License of This Document</h2>
3077    
3078  <p>Copyright 2007 <a href="http://suika.fam.cx/~wakaba/who?">Wakaba</a></p>  <p>Copyright <time>2007</time>‐<time>2008</time>
3079  <p>This library is free software; you can redistribute it  <a href="http://suika.fam.cx/~wakaba/who?" rel="author" xml:lang="ja">Wakaba</a>
3080    <code class="mail">&lt;<a href="mailto:[email protected]">[email protected]</a>&gt;</code>.</p>
3081    
3082    <p>This document is free software; you can redistribute it
3083  and/or modify it under the same terms as Perl itself.</p>  and/or modify it under the same terms as Perl itself.</p>
3084  </section>  </section>
3085    

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Removed from v.1.3  
changed lines
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