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revision 1.3 by wakaba, Mon Jul 16 10:55:11 2007 UTC revision 1.36 by wakaba, Sun Aug 31 13:28:12 2008 UTC
# Line 1  Line 1 
1  <!DOCTYPE html><html id="error-description" lang="en" xmlns:d="http://suika.fam.cx/~wakaba/archive/2007/wdcc-desc/" xmlns="http://www.w3.org/1999/xhtml">  <!DOCTYPE html><html id="error-description" lang="en" xmlns:d="http://suika.fam.cx/~wakaba/archive/2007/wdcc-desc/" xmlns="http://www.w3.org/1999/xhtml">
2  <head>  <head>
3  <title xml:lang="en">Description of Errors —  <base href="cc/">
4  Web Document Conformance Checker (BETA)</title>  
5  <link href="cc-style" rel="stylesheet">  
6    <link href="../cc-style" rel="stylesheet">
7  <link href="#license" rel="license">  <link href="#license" rel="license">
8  </head>  <title xml:lang="en">Description of Errors — WebHACC (β)</title></head>
9  <body>  <body>
10  <h1>Description of Errors</h1>  <header>
11    <h1><a href="../cc-about"><abbr title="Web Hypertext Application Conformance Checker (β)"><img alt="WebHACC" src="../icons/title"></abbr></a></h1>
12    <h2>Description of Errors</h2>
13    </header>
14    
 <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="illegal-octets-error"><h3>An illegal octet in the input stream.</h3></div>
36    </section>
37    
38    <section id="html5-character-encoding">
39    <h2>HTML5 Character Encoding Errors</h2>
40    
41    <div class="section" id="disallowed-character-encoding"><h3>Character encoding <code><var>{text}</var></code>
42      is not allowed for <abbr>HTML</abbr> document.</h3>
43        <p>The character encoding used for the document is not allowed
44        for <abbr>HTML</abbr> document.  The document is non‐conforming.</p>
45      </div>
46    
47    <div class="section" id="bad-character-encoding"><h3>Character encoding <code><var>{text}</var></code>
48      should not be used for <abbr>HTML</abbr> document.</h3>
49        <p>The character encoding used for the document is not recommended
50        for <abbr>HTML</abbr> document.  The document is non‐conforming
51        unless there is any good reason to use that encoding.</p>
52      </div>
53    
54    <div class="section" id="non-utf-8-character-encoding"><h3>Use of UTF-8 is encouraged (this document
55      is encoded in <code><var>{text}</var></code>).</h3>
56        <p>Use of UTF-8 as the character encoding of the document is encouraged,
57        though the use of another character encoding is still conforming.</p>
58      </div>
59    
60    <div class="section" id="character-encoding-unchecked"><h3>Conformance for character encoding requirements
61      cannot be checked, since the input is not a byte stream.</h3>
62        <p>The conformance checker cannot detect whether the input document
63        met the requirements on character encoding, since the document
64        is not inputed as a serialized byte sequence.  The document is
65        not conforming if it is not encoded in an appropriate character
66        encoding with appropriate labeling.</p>
67      </div>
68    
69    <div class="section" id="no-character-encoding-declaration"><h3>There is no character encoding
70      declaration.</h3>
71        <p>The document does not contain a character encoding
72        declaration.  Unless the character encoding is explicitly
73        specified in lower‐level protocol, e.g. in <abbr>HTTP</abbr>,
74        or is implied by <abbr>BOM</abbr>, there must be a character
75        encoding declaration.  The document is non‐conforming.</p>
76    
77        <p>The long character encoding declaration syntax
78        <code class="html bad example">&lt;meta http-equiv="Content-Type" content="text/html; charset=<var>charset-name</var>"&gt;</code>
79        is obsolete.  The new syntax is:</p>
80        <pre class="html example">
81    <code>&lt;meta charset="<var>charset-name</var>"&gt;</code></pre>
82    
83        <p>Note that the <code>encoding</code> declaration in <abbr>XML</abbr>
84        declaration has no effect for <abbr>HTML</abbr> document.</p>
85      </div>
86    
87    <div class="section" id="non-ascii-superset"><h3>No character encoding metadata is found
88      in lower‐level protocol nor is there <abbr>BOM</abbr>, while
89      character encoding <code><var>{text}</var></code>
90      is not a superset of <abbr>ASCII</abbr>.</h3>
91        <p>The document is not labeled with character encoding name
92        in lower‐level protocol, e.g. in <abbr>HTTP</abbr>, and
93        the document is not begin with <abbr>BOM</abbr>.  In addition,
94        the character encoding of the document is not a superset of
95        <abbr>ASCII</abbr>.  The document is non‐conforming.</p>
96    
97        <p>Unless there is a <abbr>BOM</abbr>, the character encoding
98        for the document must be specified in e.g. <abbr>HTTP</abbr>‐level,
99        as:</p>
100        <pre class="http example">
101    <code>Content-Type: text/html; charset=<var>charset-name</var></code></pre>
102    
103        <p>Existence of <abbr>HTML</abbr> character encoding declaration, i.e.
104        <code class="html example">&lt;meta charset="<var>charset-name</var>"&gt;</code>,
105        does not allow to omit <code>charset</code> parameter
106        for <abbr>HTML</abbr> document encoded in non‐<abbr>ASCII</abbr>
107        compatible encoding.</p>
108    
109        <p>Character encodings <code>Shift_JIS</code>, <code>Windows-31J</code>,
110        and <code>ISO-2022-JP</code> are <em>not</em> a superset of
111        <abbr>ASCII</abbr> for the purpose of <abbr>HTML</abbr> conformance.</p>
112      </div>
113    
114    <div class="section" id="sniffing:chardet"><h3>Character encoding of this document is sniffed
115      as <code><var>{text}</var></code> (Sniffed because no explicit specification
116      for the character encoding of this document is found in the transfer
117      procotol headers).</h3></div>
118    
119    <div class="section" id="sniffing:default"><h3>Character encoding of this document is defaulted
120      to <code><var>{text}</var></code> because no explicit specification
121      for the character encoding of this document is found in the transfer
122      procotol headers.</h3></div>
123    
124    <div class="section" id="chardecode:fallback"><h3>Since no decoder for the document character
125      encoding is found, decoder for the character encoding
126      <code><var>{text}</var></code> is used.  Checking results might be
127      <em>wrong</em>.</h3></div>
128    
129    <div class="section" id="chardecode:no-error"><h3>Conformance error checking for the character
130      encoding <code><var>{text}</var></code> is not supported.</h3></div>
131    
132    <div class="section" id="charset-label:matching"><h3>Sniffed character encoding
133      <code><var>{text}</var></code> is same as the character encoding specified
134      in the character encoding declaration.  This is <em>not</em> an
135      error.</h3></div>
136    
137    <div class="section" id="charset-label-detected"><h3>While parsing the document as
138      <code><var>{text}</var></code>, a character encoding declaration specifying
139      a different character encoding is found.  The document
140      is reparsed.</h3>
141        <p>While parsing a document in a character encoding,
142        a character encoding declaration which declares the character
143        encoding of the document as another character encoding is found.
144        The occurence of this warning itself does not make the document
145        non‐conforming.  However, the failure of the first attempt to
146        to detect the character encoding might be a result of non‐conformance
147        of the document.</p>
148    
149        <p>The document will be reparsed from the beginning.  Some error
150        or warning might be reported again.</p>
151    
152        <p>These are suggestions to avoid this warning:</p>
153        <ul>
154        <li>Specify <code>charset</code> parameter in the <code>Content-Type</code>
155        field in the <abbr>HTTP</abbr> header, as:
156        <pre class="HTTP example">
157    <code>Content-Type: text/html; charset="<var>charset-name</var>"</code></pre></li>
158        <li>Put the character encoding declaration
159        (<code class="html example">&lt;meta charset="<var>charset-name</var>"&gt;</code>)
160        just after <code class="html example">&lt;head&gt;</code> start tag.</li>
161        <li>Use <code>UTF-8</code>.</li>
162        </ul>
163      </div>
164    
165    <div class="section" id="NULL"><h3>The <code class="charname">NULL</code> character
166      is not allowed.</h3></div>
167    
168    <div class="section" id="control-char"><h3>Code point <code><var>{text}</var></code> is
169      not allowed.</h3></div>
170    
171    </section>
172    
173    <section id="html5-tokenize-error">
174    <h2>HTML5 Parse Errors in Tokenization Stage</h2>
175    
176    <div class="section" id="bad-attribute-name"><h3>Attribute name cannot contain characters
177      <code>"</code>, <code>'</code>, and <code>=</code>.</h3></div>
178    
179    <div class="section" id="bad-attribute-value"><h3>Attribute value must be quoted by <code>"</code>
180      or <code>'</code> if it contains a <code>"</code>, <code>'</code>, or
181      <code>=</code> character.</h3>
182        <p>In an unquoted attribute value, a character <code>"</code>
183        (<code>U+0022</code> <code class="charname">QUOTATION MARK</code>),
184        <code>'</code> (<code>U+0026</code>
185        <code class="charname">APOSTROPHE</code>), or <code>=</code>
186        (<code>U+003D</code> <code class="charname">EQUAL SIGN</code>)
187        is contained.  These characters are not allowed in unquoted attribute
188        values, since they are used to quote attribute values or to separate
189        attribute name and value.</p>
190    
191        <p>This error is also raised if one try to use empty attribute
192        value like <code class="html bad example">&lt;foo bar= baz=&gt;</code>;
193        in this example, <code class="html bad example">baz=</code> is
194        treated as an invalid attribute value for the attribute
195        <code class="html bad example">bar</code>, not as another attribute.</p>
196      </div>
197    
198    <div class="section" id="bare-ero"><h3>The <code>&amp;</code> character must
199      be escaped as <code class="html example">&amp;amp;</code>.</h3>
200        <p>An <code>&amp;</code> character which
201      is not part of any reference appears in the input stream.      is not part of any reference appears in the input stream.
202      The document is non-conforming.</p>      The document is non‐conforming.</p>
203    
204        <p><em>Any <code>&amp;</code> character in URI (or IRI)
205        must be escaped as <code class="example">&amp;amp;</code>.</em></p>
206    
207      <p>The <code>&amp;</code> character must      <p>The <code>&amp;</code> character must
208      be the first character of a reference:      be the first character of a reference:
209        <dl>        <dl class="switch">
210        <dt>Named entity reference</dt>        <dt>Named entity reference</dt>
211            <dd><pre class="html example">            <dd><pre class="html example">
212  <code>&amp;<var>entity-name</var>;</code></pre>  <code>&amp;<var>entity-name</var>;</code></pre>
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232      </p>      </p>
233    </div>    </div>
234    
235  <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
236      by a tag name.</h3>
237        <p>There is a <code>&lt;</code> (<code>U+003C</code>
238        <code class="charname">LESS-THAN SIGN</code>) character
239        immediately followed by a <code>/</code> (<code>U+005F</code>
240        <code>SOLIDUS</code>) character, which is not part
241        of any end tag, in the input stream.  The document
242        is non-conforming.</p>
243    
244        <p>The <code>&lt;/</code> sequence immediately followed
245        by an <abbr title="End of file pseudo-character">EOF</abbr> is
246        interpreted as a string data of <code>&lt;/</code>.</p>
247    
248        <p>The <code>&lt;/</code> sequence as string data must
249        be escaped as:
250        <pre class="html example">
251    <code>&amp;lt;/</code></pre>
252        </p>
253      </div>
254    
255    <div class="section" id="bare-stago"><h3>A <code>&lt;</code> character is not followed
256      by tag name or by a <code>!</code> character.</h3>
257        <p>A <code>&lt;</code> (<code>U+003C</code>
258        <code class="charname">LESS-THAN SIGN</code>) character which is not part
259        of any markup appears in the input stream.</p>
260    
261        <p>The <code>&lt;</code> character as a data character must
262        be escaped as:
263        <pre class="html example">
264    <code>&amp;lt;</code></pre>
265        </p>
266      </div>
267    
268    <div class="section" id="bare-nero"><h3>The decimal representation of the code position
269    of a character must be specified after <code>&amp;#</code>.</h3>    of a character must be specified after <code>&amp;#</code>.</h3>
270      <p>An <code>&amp;</code> (<code>U+0026</code>      <p>An <code>&amp;</code> (<code>U+0026</code>
271      <code class="charname">AMPERSAND</code>) character immediately      <code class="charname">AMPERSAND</code>) character immediately
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275      The document is non-conforming.</p>      The document is non-conforming.</p>
276    
277      <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  
278      of a reference:      of a reference:
279        <dl>        <dl class="switch">
280        <dt>Numeric character reference</dt>        <dt>Numeric character reference</dt>
281            <dd><pre class="html example">            <dd><pre class="html example">
282  <code>&amp;#<var>d</var>;</code></pre>  <code>&amp;#<var>d</var>;</code></pre>
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291      </p>      </p>
292    
293      <p>To represent <code>&amp;#</code> as data characters, use      <p>To represent <code>&amp;#</code> as data characters, use
294      named entity reference:      a named entity reference for the <code>&amp;</code> character:
295        <pre class="html example">        <pre class="html example">
296  <code>&amp;amp;#</code></pre>  <code>&amp;amp;#</code></pre>
297      </p>      </p>
298    </div>    </div>
299    
300  <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
301    of a character must be specified after <code>&amp;#x</code>.</h3>    of a character must be specified after <code>&amp;#x</code>.</h3>
302     <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
303     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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311      of the code point of the character to be referenced.</p>      of the code point of the character to be referenced.</p>
312    
313      <p>To represent <code>&amp;#x</code> as data characters, use      <p>To represent <code>&amp;#x</code> as data characters, use
314      named entity reference:      a named entity reference for the <code>&amp;</code> character:
315        <pre class="html example">        <pre class="html example">
316  <code>&amp;amp;#x</code></pre>  <code>&amp;amp;#x</code></pre>
317      </p>      </p>
318    </div>    </div>
319    
320  <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
321      by <code>--</code>.</h3>
322        <p>There is a <code>&lt;</code> (<code>U+003C</code>
323        <code class="charname">LESS-THAN SIGN</code>) character
324        followed by a <code>!</code> (<code>U+0021</code>
325        <code class="charname">EXCLAMATION MARK</code>) character,
326        which is not followed by a <code>--</code> or
327        <code>!DOCTYPE</code>.  The document is non-conforming.</p>
328    
329        <dl class="switch">
330        <dt>Comments</dt>
331          <dd>In HTML document, comments must be introduced by
332          <code class="example">&lt;!--</code> (<code>&lt;!</code>
333          <em>immediately</em> followed
334          by <em>two</em> <code>-</code>s) and must be terminated by
335          <code class="example">--&gt;</code>.
336          Strings <code>&lt;!</code> not followed
337          by <code>--</code> and <code>&lt;!-</code> not followed by
338          <code>-</code> are not valid open delimiters for comments.</dd>
339        <dt>Marked sections, including <code>CDATA</code> sections</dt>
340          <dd>Marked sections are not allowed in HTML document.</dd>
341        <dt>Markup declarations</dt>
342          <dd>Markup declarations, except for <code>DOCTYPE</code>
343          and comment declarations, are not allowed in HTML document.</dd>
344        <dt>String <code>&lt;!</code></dt>
345          <dd>String <code>&lt;!</code> must be escaped as
346          <code class="example">&amp;lt;!</code>.</dd>
347        </dl>
348      </div>
349    
350    <div class="section" id="bogus-end-tag"><h3>String <code>&lt;/</code> is not followed
351      by tag name.</h3>
352        <p>There is a <code>&lt;</code> (<code>U+003C</code>
353        <code class="charname">LESS-THAN SIGN</code>) character
354        immediately followed by a <code>/</code> (<code>U+005F</code>
355        <code>SOLIDUS</code>) character, which is not part
356        of any end tag, in the input stream.  The document
357        is non-conforming.</p>
358    
359        <p>The <code>&lt;/</code> sequence not followed by a
360        tag name is parsed as an opening of bogus comment.</p>
361    
362        <p>The <code>&lt;/</code> sequence as string data must
363        be escaped as:
364        <pre class="html example">
365    <code>&amp;lt;/</code></pre>
366        </p>
367      </div>
368    
369    <div class="section" id="C1-character-reference"><h3>Character reference to
370      <code><var>{text}</var></code> is not allowed.</h3></div>
371    
372    <div class="section" id="CR-character-reference"><h3>Character reference to
373      <code>U+000D</code> (<code class="charname">CARRIAGE RETURN</code>)
374      is not allowed.</h3></div>
375    
376    <div class="section" id="dash-in-comment"><h3>There is a <code>--</code> sequence
377      in a comment.</h3>
378        <p>There is a <code>-</code> (<code>U+002D</code>
379        <code class="charname">HYPHEN-MINUS</code>) character
380        at the end of the comment or a <code>--</code> sequence
381        in the comment.  The document is non-conforming.</p>
382    
383        <p>Comments cannot contain a string <code>--</code>, as in XML.
384        Unlike SGML, there cannot be more than one comments
385        (where <i>comment</i> is an SGML term) in the comment
386        declaration.</p>
387      </div>
388    
389    <div class="section" id="duplicate-attribute"><h3>There are two attributes with name
390          <code><var>{text}</var></code>.</h3>
391      <p>There are more than one attributes with the same      <p>There are more than one attributes with the same
392      name in a tag.  The document is non-conforming.</p>      name in a tag.  The document is non-conforming.</p>
393    
# Line 117  Web Document Conformance Checker (BETA)< Line 395  Web Document Conformance Checker (BETA)<
395      Use <code>img</code> element with animation GIF instead.</p>      Use <code>img</code> element with animation GIF instead.</p>
396    </div>    </div>
397    
398  <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
399      allowed.</h3></div>
400    
401    <div class="section" id="empty-end-tag"><h3>Empty end tag (<code>&lt;/&gt;</code>) is not
402      allowed.</h3></div>
403    
404    <div class="section" id="end-tag-attribute"><h3>End tag cannot have attributes.</h3></div>
405    
406    <div class="section" id="empty-unquoted-attribute-value"><h3>Attribute value is not specified.</h3>
407        <p>The attribute value is not specified after the <code>=</code>
408        (<code>U+003C</code> <code class="charname">EQUAL SIGN</code>)
409        character.</p>
410    
411        <p>When an attribute value is empty, the <code>=</code> character after
412        the attribute name must be specified as:</p>
413    
414        <p><code class="html example">&lt;foo bar&gt;</code></p>
415    
416        <p>Instead, quotation marks can be used to explicitly represent that
417        the attribute value is empty, as:</p>
418    
419        <p><code class="html example">&lt;foo bar=""&gt;</code></p>
420    
421        <p>... or like:</p>
422    
423        <p><code class="html example">&lt;foo bar=''&gt;</code></p>
424      </div>
425    
426    <div class="section" id="invalid-character-reference"><h3>Character reference to
427      <code><var>{text}</var></code> is not allowed.</h3></div>
428    
429    <div class="section" id="nestc"><h3>Polytheistic slash (<code>/&gt;</code>) cannot be
430    used for this element.</h3>    used for this element.</h3>
431      <p>Void element syntax (<code>/&gt;</code>) must not be used      <p>Polytheistic slash (<code>/&gt;</code>) must not be used
432      for the element.  The document is non-conforming.</p>      for the element.  The document is non-conforming.</p>
433    
434      <p>The void element syntax can only be      <p>The polytheistic slash can only be
435      used for <code>base</code>, <code>link</code>, <code>meta</code>,      used for <code>base</code>, <code>link</code>, <code>meta</code>,
436      <code>hr</code>, <code>br</code>, <code>img</code>,      <code>hr</code>, <code>br</code>, <code>img</code>,
437      <code>embed</code>, <code>param</code>, <code>area</code>,      <code>embed</code>, <code>param</code>, <code>area</code>,
438      <code>col</code>, and <code>input</code> elements.</p>      <code>col</code>, and <code>input</code> elements.</p>
439    
440      <p>Note that, unlike in XML, the void element syntax has      <dl class="switch">
441        <dt><code>&lt;script/&gt;</code></dt>
442            <dd><p>The polytheistic slash cannot be used for <code>script</code>
443            element.  Even for an empty <code>script</code> element,
444            there must be an explicit end tag
445            <code class="html example">&lt;/script&gt;</code>.</p>
446    
447            <p><strong>NOTE</strong>: Though some user agents interpret
448            polytheistic slash for <code>script</code> element as the
449            closing of the element, such usage is not allowed under
450            the current standard.</p></dd>
451        <dt><code>&lt;basefont/&gt;</code>, <code>&lt;bgsound/&gt;</code>,
452        <code>&lt;frame/&gt;</code>, <code>&lt;keygen/&gt;</code>,
453        <code>&lt;spacer/&gt;</code>, <code>&lt;wbr/&gt;</code></dt>
454            <dd>These elements are themselves non-conforming.</dd>
455        <!-- isindex, image -->
456        <dt><code>&lt;command/&gt;</code>, <code>&lt;event-source/&gt;</code>,
457        <code>&lt;nest/&gt;</code>, or <code>&lt;source/&gt;</code></dt>
458            <dd>Future revision of HTML5 parsing algorithm is expected
459            to allow polytheistic slash for these elements.</dd>
460        <dt><code>&lt;a/&gt;</code>, <code>&lt;p/&gt;</code></dt>
461            <dd>These elements are not always empty and therefore
462            polytheistic slash is not allowed.  Use explicit end tag
463            to represent empty element as:
464              <pre class="example html">
465    <code>&lt;p&gt;&lt;/p&gt;</code></pre>
466            </dd>
467        </dl>
468    
469        <p>Note that, unlike in XML, the polytheistic slash has
470      no effect in HTML.</p>      no effect in HTML.</p>
471    </div>    </div>
472    
473    <div class="section" id="no-DOCTYPE-name"><h3>After the string <code>&lt;!DOCTYPE </code>, the
474      document type name must be specified.</h3></div>
475    
476    <div class="section" id="no-PUBLIC-literal"><h3>After the keyword <code>PUBLIC</code>, no
477      oublic identifier is specified.</h3></div>
478    
479    <div class="section" id="no-refc"><h3>Character reference must be closed by a
480      <code>;</code> character.</h3></div>
481    
482    <div class="section" id="no-space-before-DOCTYPE-name"><h3>After the string <code>&lt;!DOCTYPE</code>, there
483      must be at least a white space character before the document type
484      name.</h3></div>
485    
486    <div class="section" id="no-space-between-attributes"><h3>Attributes must be separeted by at least a
487      white space character.</h3></div>
488    
489    <div class="section" id="no-SYSTEM-literal"><h3>After the keyword <code>SYSTEM</code>, no
490      system identifier is specified.</h3></div>
491    
492    <div class="section" id="pio"><h3>Processing instruction
493      (<code>&lt;?<var>...</var>&gt;</code>) is not allowed in HTML
494      document.</h3>
495        <p>Processing instructions (<code>&lt;?<var>...</var>?&gt;</code>),
496        including XML declaration (<code>&lt;?xml <var>...</var>?&gt;</code>)
497        and XML style sheet <abbr title="processing instruction">PI</abbr>
498        (<code>&lt;?xml-stylesheet <var>...</var>?&gt;</code>), are not allowed
499        in the HTML syntax.  The document is non-conforming.</p>
500    
501        <dl class="switch">
502        <dt><code>&lt;?xbl?&gt;</code> (<abbr>XBL</abbr> Association)</dt>
503          <dd>An <abbr>XBL</abbr> binding cannot be associated by
504          <abbr title="processing instruction">PI</abbr> in <abbr>HTML</abbr>
505          document.  Use <code>binding</code> property in <abbr>CSS</abbr>
506          style sheet as:
507            <pre class="html example">
508    <code>&lt;style&gt;
509    p {
510      binding: url(binding.xbl);
511    }
512    &lt;/style&gt;</code></pre>
513          </dd>
514        <dt><code>&lt;?xml?&gt;</code> (XML declaration)</dt>
515            <dd>XML declaration is unnecessary for HTML documents.</dd>
516        <dt><code>&lt;?xml-stylesheet?&gt;</code> (XML style sheet
517        <abbr title="processing instruction">PI</abbr>)</dt>
518            <dd>Use HTML <code>link</code> element with <code>rel</code>
519            attribute set to <code>stylesheet</code> (or,
520            <code>alternate stylesheet</code> for an alternate style
521            sheet).
522              <pre class="example html">
523    <code>&lt;link rel=stylesheet href="path/to/stylesheet.css"&gt;</code></pre>
524            </dd>
525        <dt><code>&lt;?php?&gt;</code> or
526        <code>&lt;? <var>... <abbr>PHP</abbr> code ...</var> ?&gt;</code>
527        (<abbr>PHP</abbr> code)</dt>
528            <dd>The conformance checker does <em>not</em> support
529            checking for PHP source documents.</dd>
530        <dt>Other processing instructions</dt>
531            <dd>Processing instructions cannot be inserted in an HTML
532            document.  Use XML document or insert
533            <code>ProcessingInstruction</code> node by scripting.</dd>
534        </dl>
535    
536        <p>Web browsers will parse processing instructions as bogus
537        comments.  Some legacy Web browsers, such as IE:mac and
538        some mobile Web browsers, will display processing instructions
539        as string.</p>
540      </div>
541    
542    <div class="section" id="string-after-DOCTYPE-name"><h3>There is a bogus string after the document type
543      name.</h3></div>
544    
545    <div class="section" id="string-after-PUBLIC"><h3>There is a bogus string after the keyword
546      <code>PUBLIC</code>.</h3></div>
547    
548    <div class="section" id="string-after-PUBLIC-literal"><h3>There is a bogus string after the public
549      identifier.</h3></div>
550    
551    <div class="section" id="string-after-SYSTEM"><h3>There is a bogus string after the keyword
552      <code>SYSTEM</code>.</h3></div>
553    
554    <div class="section" id="string-after-SYSTEM-literal"><h3>There is a bogus string after the system
555      identifier.</h3></div>
556    
557    <div class="section" id="unclosed-attribute-value"><h3>Attribute value is not closed by a quotation
558      mark.</h3></div>
559    
560    <div class="section" id="unclosed-comment"><h3>Comment is not closed by a string
561      <code>--&gt;</code>.</h3></div>
562    
563    <div class="section" id="unclosed-DOCTYPE"><h3>The <code>DOCTYPE</code> is not closed by a
564      <code>&gt;</code> character.</h3></div>
565    
566    <div class="section" id="unclosed-PUBLIC-literal"><h3>The public identifier literal is not closed by a
567      quotation mark.</h3></div>
568    
569    <div class="section" id="unclosed-SYSTEM-literal"><h3>The system identifier literal is not closed by a
570      quotation mark.</h3></div>
571    
572    <div class="section" id="unclosed-tag"><h3>Tag is not closed by a <code>&gt;</code>
573      character.</h3></div>
574    
575  </section>  </section>
576    
577  <section id="html5-parse-errors">  <section id="html5-parse-errors">
578  <h2>HTML5 Parse Errors in Tree Construction Stage</h2>  <h2>HTML5 Parse Errors in Tree Construction Stage</h2>
579    
580  <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
581    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
582      is closed.</h3></div>
583    
584    <div class="section" id="after-after-frameset:/"><h3>There is an end tag
585      <code>&lt;/<var>{text}</var>&gt;</code> is after the <code>html</code> element
586      is closed.</h3></div>
587    
588    <div class="section" id="after-body"><h3>Start tag <code>&lt;<var>{text}</var>&gt;</code> is
589      not allowed after the <code>body</code> is closed.</h3></div>
590    
591    <div class="section" id="after-body:/"><h3>End tag <code>&lt;/<var>{text}</var>&gt;</code> is
592      not allowed after the <code>body</code> is closed.</h3></div>
593    
594    <div class="section" id="after-body:#text"><h3>Non‐white‐space characters are not allowed
595      after the <code>body</code> is closed.</h3></div>
596    
597    <div class="section" id="after-frameset"><h3>Start tag <code>&lt;<var>{text}</var>&gt;</code> is
598      not allowed after the <code>frameset</code> is closed.</h3></div>
599    
600    <div class="section" id="after-frameset:/"><h3>End tag <code>&lt;/<var>{text}</var>&gt;</code> is
601      not allowed after the <code>frameset</code> is closed.</h3></div>
602    
603    <div class="section" id="after-frameset:#text"><h3>Non‐white‐space characters are not allowed
604      after the <code>frame</code> is closed.</h3></div>
605    
606    <div class="section" id="after-head"><h3>The <code><var>{text}</var></code> element cannot be
607      inserted between <code>head</code> and <code>body</code>
608      elements.</h3>
609      <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
610      but before the <code>body</code> element is opened.      but before the <code>body</code> element is opened.
611      The document is non-conforming.</p>      The document is non-conforming.</p>
612    </div>    </div>
613    
614  <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
615    is not allowed in <code>table</code>.</h3>    not allowed after the <code>html</code> is closed.</h3>
616      <p>The start or end tag of an element appears in <code>table</code>.      <p>The start tag of an element appears after the
617        <code>body</code> element has been closed.  The document is
618        non-conforming.</p>
619    
620        <p>Any content of the document other than <code>head</code>
621        contents and comments must be put into the <code>body</code>
622        element.</p>
623      </div>
624    
625    <div class="section" id="after-html:/"><h3>End tag <code>&lt;/<var>{text}</var>&gt;</code> is
626      not allowed after the <code>html</code> is closed.</h3>
627        <p>The end tag of an element appears after the
628        <code>body</code> element has been closed.  The document is
629        non-conforming.</p>
630    
631        <p>Any content of the document other than <code>head</code>
632        contents and comments must be put into the <code>body</code>
633        element.</p>
634      </div>
635    
636    <div class="section" id="after-html:#text"><h3>Non‐white‐space characters are not allowed
637      after the <code>html</code> is closed.</h3></div>
638    
639    <div class="section" id="image"><h3>The <code>image</code> element is
640      obsolete.</h3></div>
641    
642    <div class="section" id="in-a:a"><h3>Anchor cannot be nested.</h3>
643        <p>HTML <code>a</code> elements cannot be nested.
644        The document is non-conforming.</p>
645    
646        <p>In the HTML syntax, a start tag of the <code>a</code>
647        implies the end tag of any opening <code>a</code> element.</p>
648      </div>
649    
650    <div class="section" id="in-body"><h3>Start tag <code>&lt;<var>{text}</var>&gt;</code>
651      is not allowed in the <code>body</code> element.</h3>
652        <p>The start or end tag of an element, which
653        cannot be a descendant of <code>body</code> element, appears
654        in the input stream while the <code>body</code> element has been opened.
655      The document is non-conforming.</p>      The document is non-conforming.</p>
656      </div>
657    
658    <div class="section" id="in-body:#eof"><h3>Some element is not closed before the end of
659      file.</h3></div>
660    
661    <div class="section" id="in-button:button"><h3>The <code>button</code> element cannot be
662      nested.</h3></div>
663    
664    <div class="section" id="in-CDATA:#eof"><h3>Element is not closed before the end of
665      file.</h3></div>
666    
667    <div class="section" id="in-form:form"><h3>Start tag <code>&lt;form&gt;</code> is
668      not allowed in a <code>form</code> element.</h3></div>
669    
670    <div class="section" id="in-frameset"><h3>Start tag <code>&lt;<var>{text}</var>&gt;</code> is
671      not allowed in a <code>framset</code> element.</h3></div>
672    
673    <div class="section" id="in-frameset:/"><h3>End tag <code>&lt;/<var>{text}</var>&gt;</code> is
674      not allowed in a <code>frameset</code> element.</h3></div>
675    
676    <div class="section" id="in-frameset:#text"><h3>Non‐white‐space characters are not allowed
677      in a <code>frameset</code> element.</h3></div>
678    
679    <div class="section" id="in-head:head"><h3>Start tag <code>&lt;head&gt;</code>
680      is not allowed in the <code>head</code> element.</h3>
681        <p>There is a start tag <code>&lt;head&gt;</code> in the
682        <code>&lt;head&gt;</code> element.  The document is non-conforming.</p>
683    
684        <p>In an HTML document there must not be more than
685        one <code>head</code> element, therefore no more than one
686        start tag <code>&lt;head&gt;</code> can appear in the input stream.</p>
687      </div>
688    
689    <div class="section" id="in-html:#DOCTYPE"><h3>A <code>DOCTYPE</code> appears after any
690      element or data character has been seen.</h3>
691        <p>A <code>DOCTYPE</code> appears after any element or data character
692        has been seen.  The document is non-conforming.</p>
693        
694        <p>The <code>DOCTYPE</code> must be placed before any
695        tag, reference, or data character.  Only white space characters
696        and comments can be inserted before the <code>DOCTYPE</code>.</p>
697      </div>
698    
699    <div class="section" id="in-nobr:nobr"><h3>The <code>nobr</code> element cannot be
700      nested.</h3></div>
701    
702    <div class="section" id="in-noscript"><h3>The <code><var>{text}</var></code> element is not
703      allowed in a <code>noscript</code> element in the
704      <code>head</code> element.</h3></div>
705    
706    <div class="section" id="in-noscript:/"><h3>An end tag <code>&lt;/<var>{text}</var>&gt;</code>
707      appers before the <code>noscript</code> element is closed.</h3></div>
708    
709    <div class="section" id="in-noscript:#eof"><h3>A <code>noscript</code> element is not closed
710      before the end of file.</h3></div>
711    
712    <div class="section" id="in-noscript:#text"><h3>Non‐white‐space characters are not allowed
713      in a <code>noscript</code> element in the <code>head</code>
714      element.</h3></div>
715    
716    <div class="section" id="in-PCDATA:#eof"><h3>Element is not closed before the end of
717      file.</h3></div>
718    
719    <div class="section" id="in-select"><h3>Start tag <code>&lt;<var>{text}</var>&gt;</code>
720      is not allowed in a <code>select</code> element.</h3></div>
721    
722    <div class="section" id="in-select:/"><h3>End tag <code>&lt;/<var>{text}</var>&gt;</code>
723      is not allowed in a <code>select</code> element.</h3></div>
724    
725    <div class="section" id="in-table"><h3>Start tag <code>&lt;<var>{text}</var>&gt;</code>
726      is not allowed in a <code>table</code> element.</h3>
727        <p>The start or end tag of an element, which
728        cannot be a child of <code>table</code> element, appears
729        in the input stream while the <code>table</code> element has been opened
730        but no other element has been opened.  The document is non-conforming.</p>
731    
732      <p>In <code>table</code>, only table related elements      <p>In <code>table</code>, only table related elements
733      are allowed; any other element must be contained in      are allowed; any other element must be contained in
# Line 156  Web Document Conformance Checker (BETA)< Line 736  Web Document Conformance Checker (BETA)<
736      a table caption.</p>      a table caption.</p>
737    </div>    </div>
738    
739  <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>
740    <code>table</code>.</h3>    is not allowed in a <code>table</code> element.</h3></div>
741      <p>A data character appears in <code>table</code>.  The document  
742      is non-conforming.</p>  <div class="section" id="in-table:#text"><h3>Non‐white‐space character is not allowed within
743      the <code>table</code> element, outside of the caption and cells.</h3>
744        <p>A non‐white‐space character appears in <code>table</code>.
745        The document is non-conforming.</p>
746    
747      <p>In <code>table</code>, only table related elements      <p>In <code>table</code>, only table related elements
748      are allowed; any other element and data character must be contained in      are allowed; any other element and data character must be contained in
# Line 168  Web Document Conformance Checker (BETA)< Line 751  Web Document Conformance Checker (BETA)<
751      a table caption.</p>      a table caption.</p>
752    </div>    </div>
753    
754  <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
755      obsolete.</h3></div>
756    
757    <div class="section" id="missing-start-tag:tr"><h3>Start tag of <code>tr</code>
758    element is missing.</h3>    element is missing.</h3>
759      <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>
760      optional, is missing.  The document is non-conforming.</p>      optional, is missing.  The document is non-conforming.</p>
# Line 180  Web Document Conformance Checker (BETA)< Line 766  Web Document Conformance Checker (BETA)<
766      these start tags, it must be explicitly specified.</p>      these start tags, it must be explicitly specified.</p>
767    </div>    </div>
768    
769  <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
770    <code>DOCTYPE</code>.</h3>    <code>DOCTYPE</code>.</h3>
771      <p>The document does not start with a <code>DOCTYPE</code>.      <p>The document does not start with a <code>DOCTYPE</code>.
772      The document is non-conforming.</p>      The document is non-conforming.</p>
# Line 191  Web Document Conformance Checker (BETA)< Line 777  Web Document Conformance Checker (BETA)<
777      </p>      </p>
778    
779      <p>Only white space characters and comments are allowed      <p>Only white space characters and comments are allowed
780      before the <code>DOCTYPE</code>.</p>      before the <code>DOCTYPE</code>.  XML declaration is <em>not</em>
781        allowed in HTML document.</p>
782    </div>    </div>
783    
784  <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
785    closed.</h3>    closed.</h3>
786      <p>End tag of an element is not found before, for example,      <p>End tag of an element is not found before, for example,
787      an end tag of another element appears or      an end tag of another element appears or
788      the end of the document.  The document is non-conforming.</p>      the end of the document.  The document is non-conforming.</p>
789    
790        <p>Only <code>body</code>, <code>colgroup</code>, <code>dd</code>,
791        <code>dt</code>, <code>head</code>, <code>html</code>, <code>li</code>,
792        <code>ol</code>, <code>option</code>, <code>optgroup</code>,
793        <code>p</code>, <code>rb</code>, <code>rp</code>, <code>rt</code>,
794        <code>tbody</code>, <code>td</code>, <code>tfoot</code>,
795        <code>th</code>, <code>thead</code>, <code>tr</code>,
796        <code>ul</code> end tag can be omitted in HTML documents.
797        For any element except for void element, there must be an explicit
798        end tag.</p>
799    
800        <dl class="switch">
801        <dt>HTML <code>canvas</code> element</dt>
802          <dd>Though the element is void in earlier versions of Safari,
803          the <code>canvas</code> element is <em>no</em> longer
804          defined as empty.  There must be an end tag
805          <code class="html example">&lt;/canvas&gt;</code>.</dd>
806        </dl>
807    
808        <p>Note that misnesting tags, such as
809        <code class="bad example">&lt;a&gt;&lt;b&gt;&lt;/a&gt;&lt;/b&gt;</code>, are not
810        allowed and they also cause this error.</p>
811      </div>
812    
813    <div class="section" id="not-first-start-tag"><h3>This <code>&lt;html&gt;</code> tag is not
814      the first start tag.</h3>
815        <p>There is a start tag of the <code>html</code> element
816        that it not the first start tag in the input stream.
817        The document is non-conforming.</p>
818    
819        <p>In an HTML document, there cannot be more than one
820        <code>html</code> element and therefore there cannot be
821        more than one <code>&lt;html&gt;</code> tag.  In addition,
822        nothing can be placed before the <code>&lt;html&gt;</code> tag
823        except a <code>DOCTYPE</code>, white space characters,
824        and comments.</p>
825    </div>    </div>
826    
827  <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
828    HTML.</h3>    HTML.</h3>
829      <p>The document contains a <code>DOCTYPE</code> declaration      <p>The document contains a <code>DOCTYPE</code> declaration
830      that is different from HTML5 <code>DOCTYPE</code> (i.e. <code>&lt;!DOCTYPE      that is different from HTML5 <code>DOCTYPE</code> (i.e.
831      HTML&gt;</code>).  The document is non-conforming.</p>      <code class="example html">&lt;!DOCTYPE HTML&gt;</code>).
832        The document is non‐conforming.</p>
833    
834      <p>The document might or might not be conformant to      <p>The document might or might not be conformant to
835      some version of HTML.  However, conformance to any HTML      some version of HTML.  However, conformance to any HTML
# Line 214  Web Document Conformance Checker (BETA)< Line 838  Web Document Conformance Checker (BETA)<
838      HTML document (roughly) as defined in HTML5.</p>      HTML document (roughly) as defined in HTML5.</p>
839    </div>    </div>
840    
841  <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
842    opened.</h3></div>    not allowed here.</h3></div>
843    
844    <div class="section" id="unmatched-end-tag"><h3>Element <code><var>{text}</var></code> is not
845      opened.</h3>
846        <p>An end tag appears though no element with the same name
847        has been opened.  The document is non-conforming.</p>
848    
849        <p>For any end tag in HTML document, there must be a
850        corresponding start tag.</p>
851    
852        <dl class="switch">
853        <dt>HTML <code>base</code>, <code>basefont</code>,
854        <code>bgsound</code>, <code>br</code>, <code>col</code>,
855        <code>embed</code>, <code>frame</code>, <code>hr</code>,
856        <code>image</code>, <code>img</code>, <code>input</code>,
857        <code>isindex</code>, <code>link</code>, <code>meta</code>,
858        <code>param</code>, <code>spacer</code>, or <code>wbr</code> element</dt>
859          <dd>End tag is not allowed for these elements, since
860          those content must always be empty.  Remove end tag.</dd>
861        <!-- keygen -->
862        <!-- command, event-source, nest, source -->
863        </dl>
864      </div>
865    
866  </section>  </section>
867    
868  <section id="element-content-model-errors">  <section id="element-content-model-errors">
869  <h2>Element Content Model Errors</h2>  <h2>Element Content Model Errors</h2>
870    
871  <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
872      <code>href</code> attribute specified cannot be placed after
873      any attribute with a URL.</h3></div>
874    
875    <div class="section" id="basetarget-after-hyperlink"><h3>The <code>base</code> element with the
876      <code>target</code> attribute specified cannot be placed after
877      any element that defines a hyperlink.</h3></div>
878    
879    <div class="section" id="character-not-allowed"><h3>Data character is not allowed in this
880    context.</h3>    context.</h3>
881      <p>A data character appears where it is not allowed in this      <p>A data character appears where it is not allowed in this
882      context.  The document is non-conforming.</p>      context.  The document is non-conforming.</p>
883    
884      <p>Possible causes:      <p>Possible causes:
885        <dl>        <ul>
886        <dt>If the erred element is an inline-level element (such        <li><p>A data character cannot be a child
887        as <code>a</code> or <code>span</code>)</dt>        of certain sectioning elements such as <code>body</code>,
888            <dd><p>A data character cannot be a child        <code>section</code>, and <code>blockquote</code>.</p>
889            of certain sectioning elements such as <code>body</code>,  
890            <code>section</code>, and <code>blockquote</code>.</p>        <p>Any inline-level content must be put
891          in e.g. paragraph element such as <code>p</code>.</p></li>
892            <p>Any inline-level content must be put        <li><p>Though some elements such as <code>div</code>,
893            in e.g. paragraph element such as <code>p</code>.</p></dd>        <code>li</code>, and <code>td</code> allow
894        <dt>If the erred element is a block-level element (such as        <em>either one</em> of block-level or inline-level content
895        <code>div</code> or <code>h<var>n</var></code>)</dt>        is allowed.  If there is a block-level content,
896            <dd><p>Though some elements such as <code>div</code>,        any inline-level content must be put
897            <code>li</code>, and <code>td</code> allow        in e.g. paragraph element such as <code>p</code>.</p></li>
898            <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>  
899      </p>      </p>
900    </div>    </div>
901    
902  <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
903    element as a child of this element.</h3>    an empty element.</h3></div>
904    
905    <div class="section" id="character-not-allowed:atom|PersonConstruct"><h3>Non‐white‐space characters are not allowed in
906      Person construct.</h3></div>
907    
908    <div class="section" id="character-not-allowed:atom|TextConstruct"><h3>Non‐white‐space characters are not allowed in
909      Text construct.</h3></div>
910    
911    <div class="section" id="child-element-missing"><h3>There must be an element
912      <code><var>{text}</var></code> as a child of this element.</h3>
913      <p>The content model of the element is so defined that it      <p>The content model of the element is so defined that it
914      must contain a <code><var>$0</var></code> child element.      must contain a <code><var>$0</var></code> child element.
915      The document is non-conforming.</p>      The document is non-conforming.</p>
916    
917      <p>For example:      <dl class="switch">
918        <ul>      <dt>HTML <code>head</code> element</dt>
919        <li>The <code>head</code> element must contain exactly one        <dd>There must be a <code>title</code> child element.</dd>
920        <code>title</code> child element.</li>      <dt>HTML <code>html</code> element</dt>
921        <li><a href="#child-element-missing:td%7Cth">The <code>tr</code>        <dd>There must be a <code>head</code> child element followed
922        element must contain one or more <code>td</code> or <code>th</code>        by a <code>body</code> element.</dd>
923        child element.</a></li>      <dt>HTML <code>tr</code> element</dt>
924        </ul>        <dd><a href="#child-element-missing:td%7Cth">There must be
925      </p>        one or more <code>td</code> or <code>th</code> child element.</a></dd>
926        </dl>
927    </div>    </div>
928    
929  <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>
930    or <code>th</code> element as a child of this element.</h3>    or <code>th</code> element as a child of this element.</h3>
931      <p>The <code>tr</code> element must contain at least one      <p>The <code>tr</code> element must contain at least one
932      <code>td</code> or <code>th</code> child element.  The document      <code>td</code> or <code>th</code> child element.  The document
933      is non-conforming.</p>      is non-conforming.</p>
934    </div>    </div>
935    
936  <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
937      <code><var>{text}</var></code> in the Atom namespace as a child of this
938      element.</h3></div>
939    
940    <div class="section" id="child-element-missing:atom:link:alternate"><h3>There must be an Atom <code>link</code> element
941      whose <code>rel</code> attribute is set to <code>alternate</code> as a
942      child of this element.</h3></div>
943    
944    <div class="section" id="child-element-missing:atom:link:self"><h3>There should be an Atom <code>link</code> element
945      whose <code>rel</code> attribute is set to <code>self</code> as a
946      child of this element.</h3></div>
947    
948    <div class="section" id="element-missing:hn"><h3>There must be at least one
949      <code>h<var>n</var></code> element descendant.</h3></div>
950    
951    <div class="section" id="element-not-allowed"><h3>This element is not allowed in this
952    context.</h3>    context.</h3>
953      <p>An element appears where it is not allowed.  The document      <p>An element appears where it is not allowed.  The document
954      is non-conforming.</p>      is non-conforming.</p>
955    
     <p><strong>Note</strong>: The conformance checker does  
     <em>not</em> support form elements yet.</p>  
   
956      <p>Possible causes:      <p>Possible causes:
957        <dl>        <dl class="switch">
958        <dt>If the erred element is an inline-level element (such        <dt>If the element with the error is an inline-level element,
959        as <code>a</code> or <code>span</code>)</dt>        such as <code>a</code>, <code>progress</code>, or <code>img</code></dt>
960            <dd><p>An inline-level element cannot be a child            <dd><p>An inline-level element cannot be a child
961            of certain sectioning elements such as <code>body</code>,            of certain sectioning elements such as <code>body</code>,
962            <code>section</code>, and <code>blockquote</code>.</p>            <code>section</code>, and <code>blockquote</code>.</p>
963    
964            <p>Any inline-level content must be put            <p>Any inline-level content must be put
965            in e.g. paragraph element such as <code>p</code>.</p></dd>            in e.g. paragraph element such as <code>p</code>.</p></dd>
966        <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>,
967        <code>div</code> or <code>h<var>n</var></code>)</dt>        <code>div</code>, <code>h<var>n</var></code>,
968            <dd><p>Though some elements such as <code>div</code>,        <code>p</code>, or <code>section</code></dt>
969            <code>li</code>, and <code>td</code> allow            <dd><dl class="switch">
970            <em>either one</em> of block-level or inline-level content                <dt>If the parent element is <code>div</code>,
971            is allowed.  If there is a block-level content,                <code>li</code>, <code>td</code>, or <code>th</code></dt>
972            any inline-level content must be put                <!-- @@ TODO: more... -->
973            in e.g. paragraph element such as <code>p</code>.</p></dd>                    <!-- @@ TODO: <p><ul><li><p> -->
974        <dt>If the erred element is the root <code>html</code> element</dt>                    <dd><p>The parent element allows <em>either</em>
975            <dd><p>In an XHTML document, the root <code>html</code>                    block-level or inline-level content.  If there is a
976            element must have an <code>xmlns</code> attribute                    block-level content, any inline-level content must be
977            whose value is set to                    put in e.g. paragraph element such as <code>p</code>.</p>
978            <code>http://www.w3.org/1999/xhtml</code>.</p></dd>                    <p>For example, an HTML document fragment
979                      <code class="html bad example">&lt;div&gt;&lt;p&gt;Hello!&lt;/p&gt; World!&lt;/div&gt;</code>
980                      is non-conforming, since a word <q>World!</q> does not belong
981                      to any paragraph.  (If not part of any paragraph, what is
982                      it!?)  A conforming example would be:
983                        <pre class="html example">
984    <code>&lt;div&gt;&lt;p&gt;Hello!&lt;/p&gt; &lt;p&gt;World!&lt;/p&gt;&lt;/div&gt;</code></pre>
985                      </p></dd>
986                  <dt>If the parent element does <em>not</em> allow
987                  block-level elements as content</dt>
988                      <dd>The element is not allowed to be inserted here.
989                      For example, a <code>div</code> element cannot be
990                      a child of an <code>h1</code> element.</dd>
991              </dl></dd>
992          <dt>If the element with the error is a <code>noscript</code> element</dt>
993              <dd>The <code>noscript</code> element is allowed only in the context
994              where a block-level or inline-level content is expected
995              and in the <code>head</code> element.
996              It cannot be used in e.g. <code>ul</code>, <code>table</code>,
997              or <code>select</code>.</dd>
998          <dt>If the element with the error is <code>blink</code>,
999          <code>center</code>, or <code>marquee</code> element</dt>
1000              <dd>These elements are not part of the HTML standard.
1001              Use CSS for styling control.</dd>
1002    
1003          <dt><code>button</code>, <code>datalist</code>,
1004          <code>fieldset</code>, <code>form</code>,
1005          <code>input</code>, <code>label</code>,
1006          <code>optgroup</code>, <code>option</code>, <code>output</code>,
1007          <code>rb</code>, <code>rp</code>, <code>rt</code>, <code>ruby</code>,
1008          <code>textarea</code>, or <code>textarea</code> element</dt>
1009          <!-- rbc, rtc ? -->
1010              <dd>These elements are intentionally not supported by the conformance
1011              checker <em>yet</em>.</dd>
1012        </dl>        </dl>
1013      </p>      </p>
1014    </div>    </div>
1015    
1016    <div class="section" id="element-not-allowed:area"><h3>An <code>area</code> element cannot be used
1017      outside of a <code>map</code> element.</h3></div>
1018    
1019    <div class="section" id="element-not-allowed:base"><h3>There is another <code>base</code>
1020      element.</h3></div>
1021    
1022    <div class="section" id="element-not-allowed:datatemplate"><h3>In a <code>datatemplate</code> element, only
1023      <code>rule</code> elements are allowed.</h3></div>
1024    
1025    <div class="section" id="element-not-allowed:details-legend"><h3>In a <code>details</code> element, only at the
1026      beginning of the element a <code>lengend</code> element
1027      may be used.</h3></div>
1028    
1029    <div class="section" id="element-not-allowed:empty"><h3>Elements are not allowed in an empty
1030      element.</h3></div>
1031    
1032    <div class="section" id="element-not-allowed:figure-legend"><h3>In a <code>figure</code> element, only at the
1033      beginning or only at the end of the element a <code>lengend</code> element
1034      may be used.</h3></div>
1035    
1036    <div class="section" id="element-not-allowed:flow"><h3>This element is not allowed where flow
1037      content is expected.</h3></div>
1038    
1039    <div class="section" id="element-not-allowed:flow-style"><h3>A <code>style</code> element without
1040      <code>scoped</code> attribute is not allowed in this context.</h3></div>
1041    
1042    <div class="section" id="element-not-allowed:head-noscript"><h3>This element is not allowed in a
1043      <code>noscript</code> element in the <code>head</code> element.</h3></div>
1044    
1045    <div class="section" id="element-not-allowed:head-style"><h3>A <code>style</code> element with
1046      <code>scoped</code> attribute is not allowed in the <code>head</code>
1047      element.</h3></div>
1048    
1049    <div class="section" id="element-not-allowed:head-title"><h3>There is another <code>title</code>
1050      element.</h3></div>
1051    
1052    <div class="section" id="element-not-allowed:minus"><h3>This element is not allowed in this
1053      context.</h3></div>
1054    
1055    <div class="section" id="element-not-allowed:meta-charset"><h3>The character encoding declaration is not the
1056      first child element in the <code>head</code> element.</h3>
1057        <p>The character encoding declaration
1058        (<code class="html example">&lt;meta charset="<var>...</var>"&gt;</code> or
1059        <code class="html example">&lt;meta http-equiv=Content-Type content="text/html; charset=<var>...</var>"&gt;</code>
1060        must be the first child element in the <code>head</code> element.</p>
1061    
1062        <p>The character encoding declaration have to occur near the beginning
1063        of the document to ensure that Web browsers can be determine the
1064        character encoding of the document.</p>
1065    
1066        <p>The <code>title</code> element and other metadata elements must
1067        appear after any character encoding declaration is processed.</p>
1068      </div>
1069    
1070    <div class="section" id="element-not-allowed:metadata"><h3>This element is not allowed where metadata
1071      content is expected.</h3></div>
1072    
1073    <div class="section" id="element-not-allowed:phrasing"><h3>This element is not allowed where phrasing
1074      content is expected.</h3></div>
1075    
1076    <div class="section" id="element-not-allowed:root"><h3>This element is not allowed as the root
1077      element of a document.</h3>
1078        <p>An element that is not allowed as the root element
1079        is used as the root element of the document.  The document is
1080        non-conforming, as far as the conformance checker can tell.</p>
1081    
1082        <dl class="switch">
1083        <dt><code>html</code> element in an XHTML document</dt>
1084            <dd><p>In <abbr>XHTML</abbr> document, the root <code>html</code>
1085            element must have an <code>xmlns</code> attribute as:
1086              <pre class="xml example">
1087    <code>&lt;html xmlns="http://www.w3.org/1999/xhtml"&gt;</code></pre></p></dd>
1088        <dt><code>rss</code> element</dt>
1089            <dd><p>The document is written in some version of RSS.</p>
1090            <p>The conformance checker does not support any version
1091            of RSS.  Use Atom 1.0 for feed documents.</p></dd>
1092        <dt><code>feed</code> element</dt>
1093            <dd><p>The Atom <code>feed</code> element must be
1094            in the <code>http://www.w3.org/2005/Atom</code>
1095            namespace as:
1096              <pre class="xml example">
1097    <code>&lt;feed xmlns="http://www.w3.org/2005/Atom"&gt;</code></pre>
1098            </p>
1099            <p>The conformance checker does not support Atom 0.3.
1100            Use Atom 1.0 for feed documents.</p></dd>
1101        </dl>
1102      </div>
1103    
1104    <div class="section" id="element-not-allowed:root:xml"><h3>This element is not allowed as the root element
1105      of an XML document.</h3></div>
1106    
1107    <div class="section" id="element-not-allowed:ruby-base"><h3>This element is not allowed in the <code>ruby</code>
1108      element.</h3></div>
1109    
1110    <div class="section" id="element-not-allowed:text"><h3>This element is not allowed in this
1111      context.</h3></div>
1112    
1113    <div class="section" id="element-not-allowed:atom|content"><h3>This element is not allowed in an Atom
1114      <code>content</code> element.</h3></div>
1115    
1116    <div class="section" id="element-not-allowed:atom|PersonConstruct"><h3>This element is not allowed in Person
1117      construct.</h3></div>
1118    
1119    <div class="section" id="element-not-allowed:atom|TextConstruct"><h3>This element is not allowed in Text
1120      construct.</h3></div>
1121    
1122    <div class="section" id="element-not-defined"><h3>This element is not defined.</h3>
1123        <p>The element is not one of elements allowed
1124        in the latest version of relevant specifications.</p>
1125    
1126        <p>The element cannot be used.</p>
1127    
1128        <dl class="switch">
1129        <dt><code>event-source</code> element</dt>
1130            <dd>The element was renamed as <em><code>eventsource</code>
1131            element</em> (no hyphen).</dd>
1132        <dt><code>m</code> element</dt>
1133            <dd>The element was renamed as <em><code>mark</code>
1134            element</em>.</dd>
1135        </dl>
1136      </div>
1137    
1138    <div class="section" id="no-significant-content"><h3>No significant content is contained
1139      in this element.</h3></div>
1140    
1141    <div class="section" id="no-significant-content-before"><h3>There is no significant content
1142      before this element.</h3></div>
1143    
1144    <div class="section" id="no-significant-content-at-the-end"><h3>No significant content is contained
1145      at the end of this element.</h3></div>
1146    
1147    <div class="section" id="ps-element-missing"><h3>There is no <code><var>{text}</var></code>
1148      element before this element.</h3>
1149        <p>There must be an element before another element, but there
1150        is not.  The document is non-conforming.</p>
1151    
1152        <p>For example, there must be a <code>dt</code> element
1153        before any <code>dd</code> element.</p>
1154      </div>
1155    
1156    <div class="section" id="rp:syntax-error"><h3>The content of a <code>rp</code> element must
1157      be a parenthesis.</h3></div>
1158    
1159  </section>  </section>
1160    
1161  <section id="attribute-errors">  <section id="attribute-errors">
1162  <h2>Attribute Errors</h2>  <h2>Attribute Errors</h2>
1163    
1164  <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>
1165    is not specified.</h3>    is not specified.</h3>
1166      <p>A required attribute is not specified.  The document      <p>A required attribute is not specified.  The document
1167      is non-conforming.</p>      is non-conforming.</p>
1168    
1169      <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.  
1170      Without required attributes specified, user agents      Without required attributes specified, user agents
1171      cannot provide the full functionality of the element      cannot provide full functionality of the element to the user.</p>
     to the user.</p>  
   </div>  
1172    
1173  <div class="section attribute-error" id="in-HTML:xml:lang"><h3>The <code>xml:lang</code> attribute is not      <dl class="switch">
1174    allowed in HTML document.</h3>      <dt>HTML <code>img</code> element</dt>
1175      <p>The <code>xml:lang</code> attribute is not allowed in          <dd>The <code>src</code> attribute must be specified.
1176      HTML document.  The document is non-conforming.</p>          Additionally, the <code>alt</code> attribute must be specified
1177            in many cases.</dd>
1178      <p>The <code>xml:lang</code> attribute in <code>null</code>      <dt>HTML <code>link</code> element</dt>
1179      namespace for HTML elements is defined as conforming only for          <dd>The <code>rel</code> attribute must be specified.
1180      XML document.</p>          Note that the <code>rev</code> attribute is obsolete.</dd>
1181        </dl>
1182      </div>
1183    
1184    <div class="section" id="attribute-missing:data|type"><h3>For an <code>object</code> at least one of
1185      <code>data</code> and <code>type</code> attributes must be
1186      specified.</h3></div>
1187    
1188    <div class="section" id="attribute-missing:href|target"><h3>For a <code>base</code> element, at least one of
1189      <code>href</code> and <code>target</code> attributes must be
1190      specified.</h3></div>
1191    
1192    <div class="section" id="attribute-missing:name|http-equiv"><h3>For a <code>meta</code> element with the
1193      <code>content</code> attribute specified, exactly one of
1194      <code>name</code> and <code>http-equiv</code> attributes must be
1195      specified.</h3></div>
1196    
1197    <div class="section" id="attribute-missing:name|http-equiv|charset"><h3>For a <code>meta</code> element, exactly one of
1198      <code>name</code>, <code>http-equiv</code>, and <code>charset</code>
1199      attributes must be specified.</h3></div>
1200    
1201    <div class="section" id="attribute-not-allowed"><h3>Attribute
1202      <code><var>{local-name}</var></code> is not allowed for
1203      <code><var>{element-local-name}</var></code> element.</h3>
1204        <p>An attribute is specified where it is not allowed.
1205        The document is non-conforming.</p>
1206    
1207        <dl>
1208        <dt>HTML <code>meta</code> element</dt>
1209            <dd>For HTML <code>meta</code> element, <em>only one</em> of
1210            <code>name</code>, <code>http-equiv</code>, or <code>charset</code>
1211            attribute is allowed.</dd>
1212        </dl>
1213      </div>
1214    
1215    <div class="section" id="attribute-not-allowed:ismap"><h3>The <code>ismap</code> attribute may only be
1216      used for the image contained in an <code>a</code> element.</h3></div>
1217    
1218    <div class="section" id="attribute-not-defined"><h3>This attribute is not defined.</h3>
1219        <p>The attribute is not one of attributes allowed for the element
1220        in the latest version of relevant specifications.</p>
1221    
1222        <p>The attribute cannot be used.</p>
1223    
1224        <dl class="switch">
1225        <dt><code>align</code> attribute (various HTML elements)</dt>
1226        <dt><code>border</code> attribute (various HTML elements)</dt>
1227          <dd>These attributes are no longer part of HTML.  You can use CSS
1228          properties to control the presentation of the element.</dd>
1229        <dt><code>autosubmit</code> attribute (<code>menu</code> element)</dt>
1230          <dd>The attribute was part of HTML5 draft but then dropped.
1231          Similar functionality can be implemented by scripts.</dd>
1232        <dt><code>language</code> attribute (<code>script</code> element)</dt>
1233          <dd>The attribute is no longer the standard way to specify the
1234          scripting language.  If you are using JavaScript, then no explicit
1235          specification of the scripting language is necessary, so you can
1236          write the element like:
1237            <p><code class="html example code">&lt;script&gt;<br><!--
1238            --> /* JavaScript code */<br><!--
1239            -->&lt;/script&gt;</code></p>
1240          If you are using different scripting language from JavaScript, or
1241          you want to declare the scripting language explicitly, you should
1242          use the <code>type</code> attribute, as follows:
1243            <dl class="switch">
1244            <dt>JavaScript</dt>
1245              <dd>Use
1246              <code class="html example">&lt;script type="text/javascript"&gt;</code>.</dd>
1247            <dt>VBScript</dt>
1248              <dd>Use
1249              <code class="html example">&lt;script type="text/vbscript"&gt;</code>.</dd>
1250            </dl>
1251          </dd>
1252        </dl>
1253      </div>
1254    
1255    <div class="section" id="in-HTML:xml:lang"><h3>The <code>xml:lang</code> attribute in HTML
1256      document is ignored.</h3>
1257        <p>The <code>xml:lang</code> attribute does not have an effect in
1258        HTML document.</p>
1259    
1260        <p>The <code>xml:lang</code> attribute is only applicable to XML
1261        documents.  In HTML document, it is only allowed to ease migration
1262        from XML.</p>
1263    
1264      <p>To specify natural language information in HTML document,      <p>To specify natural language information in HTML document,
1265      use <code>lang</code> attribute instead.</p>      use <code>lang</code> attribute instead.</p>
1266    
1267        <p>XHTML 1.0 Appendix C was encouraged to specify both
1268        <code>lang</code> and <code>xml:lang</code> attributes with
1269        the same value.  Such a duplication has <em>no effect</em> in practice.
1270        Use only one of <code>lang</code> (in HTML) or <code>xml:lang</code> (in
1271        XML).</p>
1272    
1273      <!-- @@ ISSUE: xml:lang in non-HTML element in DOM5 HTML created      <!-- @@ ISSUE: xml:lang in non-HTML element in DOM5 HTML created
1274           from an HTML document? -->           from an HTML document? -->
1275    </div>    </div>
1276    
1277  <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
1278    allowed in XML document.</h3>    allowed in XML document.</h3>
1279      <p>The <code>charset</code> attribute of a      <p>The <code>charset</code> attribute of a
1280      <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 1283  Web Document Conformance Checker (BETA)<
1283      <p>To specify the character encoding used for serialization,      <p>To specify the character encoding used for serialization,
1284      if necessary, use XML declaration instead:      if necessary, use XML declaration instead:
1285        <pre class="xml example">        <pre class="xml example">
1286  <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>
1287      </p>      </p>
1288    </div>    </div>
1289    
1290  <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
1291    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>  
1292    
1293      <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
1294      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>  
1295    
1296  <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
1297    in the <code>null</code> namespace is not allowed in    in the <code>null</code> namespace is not allowed in
1298    XHTML document.  The document is non-conforming.</h3>    XHTML document.  The document is non-conforming.</h3>
1299      <p>The <code>xmlns</code> attribute in the <code>null</code>      <p>The <code>xmlns</code> attribute in the <code>null</code>
1300      namespace is not allowed in XHTML document.</p>      namespace is not allowed in XHTML document.</p>
1301    
1302      <p>This error should not occur in conformance-checking      <p>This error should not occur in conformance-checking of
1303      static documents.</p>      static documents.</p>
1304    </div>    </div>
1305    
1306    <div class="section" id="xml:lang-not-allowed"><h3>The <code>xml:lang</code> attribute is only allowed
1307      when the <code>lang</code> attribute is specified.</h3></div>
1308    
1309  </section>  </section>
1310    
1311  <section id="attribute-value-errors">  <section id="attribute-value-errors">
1312  <h2>Attribute Value Errors</h2>  <h2>Attribute Value Errors</h2>
1313    
1314  <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>
1315    values and the specified value is not one of them.</h3></div>    is not allowed.  It must be an empty string or a string
1316      <code><var>{local-name}</var></code>.</h3></div>
1317    
1318    <div class="section" id="char:syntax-error"><h3>The attribute value must be exactly one
1319      character.</h3></div>
1320    
1321    <div class="section" id="charref-in-charset"><h3>A character reference cannot be used to
1322      represent a character encoding name.</h3></div>
1323    
1324    <div class="section" id="charset:not-preferred"><h3>Character encoding name
1325      <code><var>{value}</var></code> is not the preferred name of that
1326      character encoding.</h3></div>
1327    
1328    <div class="section" id="charset:not-registered"><h3>Character encoding name
1329      <code><var>{value}</var></code> is not a registered name.</h3>
1330        <p>The specified character encoding name is not registered to
1331        <abbr>IANA</abbr>.  Use of registered character encoding name
1332        is a good practice to facilitate interoperability.</p>
1333    
1334        <dl class="switch">
1335        <dt><code>EUC-TW</code></dt>
1336          <dd><code>EUC-TW</code> is not registered.  Unfortunately, there
1337          is no registered name for that character encoding.  Use
1338          Big5 encoding with character encoding name <code>Big5</code>
1339          if it is enough to represent the document.</dd>
1340        <dt><code>ISO-2022-JP-1</code></dt>
1341          <dd><code>ISO-2022-JP-1</code> is not registered, nevertheless
1342          this character encoding name is documented in
1343          <a href="urn:ietf:rfc:2237"><abbr>RFC</abbr> 2237</a>.  Use
1344          <code>ISO-2022-JP-2</code> instead, since that character encoding
1345          is a superset of ISO-2022-JP-1.</dd>
1346        <dt><code>ISO-2022-JP-3</code>, <code>ISO-2022-JP-3-plane1</code></dt>
1347          <dd>These names are not registered and obsoleted in favor of
1348          <code>ISO-2022-JP-2004</code> and
1349          <code>ISO-2022-JP-2004-plane1</code>.</dd>
1350        <dt><code>ISO-2022-JP-2003</code>,
1351        <code>ISO-2022-JP-2003-plane1</code></dt>
1352          <dd>These names are not registered and corrected to
1353          <code>ISO-2022-JP-2004</code> and
1354          <code>ISO-2022-JP-2004-plane1</code>.</dd>
1355        <dt><code>ISO-2022-JP-2004</code>,
1356        <code>ISO-2022-JP-2004-plane1</code></dt>
1357          <dd>These names are not registered.  Unfortunately, there is
1358          no registered name for these character encodings.</dd>
1359        <dt><code>UTF-8N</code></dt>
1360          <dd><code>UTF-8N</code> is not registered.  Character encoding
1361          name <code>UTF-8</code> represents UTF-8 encoding with or
1362          without <abbr>BOM</abbr>.</dd>
1363        </dl>
1364    
1365        <p><strong>WARNING</strong>: This error might be raised for
1366        a registered character encoding name, since the character encoding
1367        name database of the conformance checker is not complete yet.</p>
1368      </div>
1369    
1370    <div class="section" id="charset:private"><h3>Character encoding name
1371      <code><var>{value}</var></code> is a private name.</h3>
1372        <p>The specified character encoding name is a private name and
1373        not registered to <abbr>IANA</abbr>.  Use of registered character
1374        encoding name is a good practice to facilitate interoperability.</p>
1375    
1376        <dl class="switch">
1377        <dt><code>x-euc-jp</code></dt>
1378          <dd>Use <code>EUC-JP</code> for the Japanese <abbr>EUC</abbr>
1379          character encoding.</dd>
1380        <dt><code>x-sjis</code></dt>
1381          <dd>Use <code>Shift_JIS</code> for standard Shift encoding scheme of
1382          <abbr>JIS</abbr> coded character set, or <code>Windows-31J</code>
1383          for Microsoft standard character set as implemented by
1384          Microsoft Windows.</dd>
1385        </dl>
1386      </div>
1387    
1388    <div class="section" id="charset:syntax-error"><h3>The specified value <code><var>{value}</var></code>
1389      is syntactically not a character encoding name.</h3>
1390        <p>The attribute value must be a character encoding name.  However,
1391        the specified value is not a character encoding name syntactically.
1392        The document is non‐conforming.</p>
1393        <p>Character encoding name is a string of <abbr>ASCII</abbr>
1394        printable characters, up to 40 characters.</p>
1395      </div>
1396    
1397    <div class="section" id="color:syntax-error"><h3>The specified value is not a color
1398      name or hexadecimal color number.</h3></div>
1399    
1400    <div class="section" id="coords:number-not-3"><h3>The <code>coords</code> attribute have to
1401      contain three (3) numbers (specified:
1402      <code><var>{text}</var></code>).</h3></div>
1403    
1404    <div class="section" id="coords:number-not-4"><h3>The <code>coords</code> attribute have to
1405      contain four (4) numbers (specified:
1406      <code><var>{text}</var></code>).</h3></div>
1407    
1408    <div class="section" id="coords:number-lt-6"><h3>The <code>coords</code> attribute have to
1409      contain more than or equal to six (6) numbers (specified:
1410      <code><var>{text}</var></code>).</h3></div>
1411    
1412    <div class="section" id="coords:number-not-even"><h3>The <code>coords</code> attribute have to
1413      contain even number of numbers (specified:
1414      <code><var>{text}</var></code>).</h3></div>
1415    
1416    <div class="section" id="coords:out-of-range"><h3>The specified value <code><var>{value}</var></code>
1417      is out of range.</h3></div>
1418    
1419    <div class="section" id="coords:syntax-error"><h3>The specified value is not valid.</h3></div>
1420    
1421    <div class="section" id="datetime:bad-year"><h3>Year number is out of range.</h3></div>
1422    
1423    <div class="section" id="datetime:bad-month"><h3>Month number is out of range.</h3></div>
1424    
1425    <div class="section" id="datetime:bad-day"><h3>Day number is out of range.</h3></div>
1426    
1427    <div class="section" id="datetime:bad-hour"><h3>Hour number is out of range.</h3></div>
1428    
1429    <div class="section" id="datetime:bad-minute"><h3>Minute number is out of range.</h3></div>
1430    
1431    <div class="section" id="datetime:bad-second"><h3>Second number is out of range.</h3></div>
1432    
1433    <div class="section" id="datetime:bad-timezone-hour"><h3>Hour number of the timezone component is out of
1434      range.</h3></div>
1435    
1436    <div class="section" id="datetime:bad-timezone-minute"><h3>Minute number of the timezone component is out of
1437      range.</h3></div>
1438    
1439    <div class="section" id="datetime:syntax-error"><h3>The attribute value is not a datetime.</h3></div>
1440    
1441    <div class="section" id="dateortime:syntax-error"><h3>The value is not a date or time.</h3></div>
1442    
1443    <div class="section" id="enumerated:invalid"><h3>This attribute only allow a limited set of
1444      values and the specified value <code><var>{@}</var></code> is not one
1445      of them.</h3>
1446        <p>For this attribute only several values are allowed and the
1447        value of the attribute is not one of them.  The document
1448        is non-conforming.</p>
1449    
1450        <dl>
1451        <dt>HTML <code>meta</code> element, <code>http-equiv</code> attribute</dt>
1452            <dd><p>Only values <code>Default-Style</code> and <code>Refresh</code>
1453            are allowed.</p>
1454            <p>Value <code>Content-Type</code> is obsolete; for charset
1455            declaration, the <code>charset</code> attribute can be used as:
1456            <pre class="html example">
1457    <code>&lt;meta charset="<var>charset-name</var>"&gt;</code></pre>
1458            ... where <var>charset-name</var> is a name of the character encoding
1459            of the document, such as <code>utf-8</code>.</p>
1460            <p>Values <code>Content-Style-Type</code> and
1461            <code>Content-Script-Type</code> are currently not allowed.</p>
1462            <p>Value <code>Keywords</code> is not allowed.  Use
1463            <code>name</code> attribute instead of <code>http-equiv</code>
1464            attribute.</p>
1465            <p>Values <code>Expires</code>, <code>Pragma</code>,
1466            and <code>Cache-Control</code> are not allowed;
1467            use <em>real</em> HTTP header fields for cache control.</p></dd>
1468        </dl>
1469      </div>
1470    
1471    <div class="section" id="enumerated:invalid:http-equiv:content-type"><h3>Character encoding declaration syntax
1472      <code class="html bad example">&lt;meta http-equiv="Content-Type" content="text/html; charset=<var>charset-name</var>"&gt;</code>
1473      is obsolete.</h3>
1474        <p>Old long character encoding declaration syntax
1475        <code class="html bad example">&lt;meta http-equiv="Content-Type" content="text/html; charset=<var>charset-name</var>"&gt;</code>
1476        is in use.  The document is non‐conforming.</p>
1477    
1478        <p>The new character encoding declaration syntax is:
1479          <pre class="html example">
1480    <code>&lt;meta charset="<var>charset-name</var>"&gt;</code></pre>
1481        </p>
1482      </div>
1483    
1484    <div class="section" id="enumerated:non-conforming"><h3>Attribute value <code><var>{@}</var></code>
1485      is not allowed.</h3></div>
1486    
1487    <div class="section" id="duplicate-http-equiv"><h3>There is another pragma
1488      <code><var>{value}</var></code>.</h3></div>
1489    
1490  <div class="section attribute-value-error" id="duplicate-ID"><h3>This identifier has already been  <div class="section" id="duplicate-ID"><h3>This identifier has already been
1491    assigned to another element.</h3></div>    assigned to another element.</h3></div>
1492    
1493  <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>
1494      appears in the attribute value twice.</h3></div>
1495    
1496    <div class="section" id="empty-attribute-value"><h3>The attribute value is empty.</h3></div>
1497    
1498    <div class="section" id="empty-style-sheet-title"><h3>The value of the <code>title</code> attribute
1499      is empty.</h3>
1500        <p>The <code>title</code> attribute value of the <code>link</code>
1501        element that defines an alternate style sheet is an empty value.</p>
1502    
1503        <p>A <code>link</code> element whose <code>rel</code> attribute
1504        is <code>alternate stylesheet</code> defines an alternate style sheet.
1505        An alternate style sheet must be associated with a name using the
1506        <code>title</code> attribute.  The name cannot be empty.</p>
1507      </div>
1508    
1509    <div class="section" id="float:out-of-range"><h3>The specified value is out of range.</h3></div>
1510    
1511    <div class="section" id="float:syntax-error"><h3>The attribute value is not a real
1512      number.</h3></div>
1513    
1514    <div class="section" id="fragment-points-itself"><h3>A fragment identifier references the element
1515      itself.</h3></div>
1516    
1517    <div class="section" id="fragment-points-nothing"><h3>A fragment identifier references no
1518      node.</h3></div>
1519    
1520    <div class="section" id="hashref:syntax-error"><h3>A hash−name reference must start with a
1521      <code>#</code> character.</h3></div>
1522    
1523    <div class="section" id="id-ne-name"><h3>The <code>id</code> attribute value is
1524      different from the <code>name</code> attribute value.</h3></div>
1525    
1526    <div class="section" id="integer:syntax-error"><h3>The attribute value is not an integer.</h3></div>
1527    
1528    <div class="section" id="link-type:bad-context"><h3>The link type <code><var>{value}</var></code>
1529      cannot be specified for this element.</h3>
1530        <p>The specified link type cannot be used for the element.
1531        The document is non-conforming.</p>
1532    
1533        <p>Link types are associated with limited set of elements.
1534        They cannot be used with other elements.</p>
1535    
1536        <p>For example, link type <code>bookmark</code>
1537        can be used with <code>a</code> or <code>area</code> element,
1538        while it cannot be used with <code>link</code> element.</p>
1539      </div>
1540    
1541    <div class="section" id="invalid-attribute-value"><h3>Attribute value <code><var>{@}</var></code>
1542      is not an allowed value.</h3></div>
1543    
1544    <div class="section" id="length:syntax-error"><h3>The attribute value is not a length
1545      value.</h3></div>
1546    
1547    <div class="section" id="link-type:non-conforming"><h3>The link type <code><var>{value}</var></code>
1548      is non-conforming.</h3>
1549        <p>The specified link type is non-conforming, and therefore
1550        the document is non-conforming.</p>
1551    
1552        <dl class="switch">
1553        <dt>Link type <code>contents</code></dt>
1554          <dd>Use link type <code>index</code>.</dd>
1555        <dt>Link type <code>copyright</code></dt>
1556          <dd>Use link type <code>license</code>.</dd>
1557        <dt>Link type <code>home</code></dt>
1558          <dd>Use link type <code>index</code>.</dd>
1559        <dt>Link type <code>previous</code></dt>
1560          <dd>Use link type <code>prev</code>.</dd>
1561        <dt>Link type <code>start</code></dt>
1562          <dd>Use link type <code>first</code>.</dd>
1563        <dt>Link type <code>toc</code> or <code>top</code></dt>
1564          <dd>Use link type <code>index</code>.</dd>
1565        </dl>
1566      </div>
1567    
1568    <div class="section" id="meta-content-type-syntax-error"><h3>The specified value is not a valid as a long
1569      character encoding declaration.</h3></div>
1570    
1571    <div class="section" id="mismatched-charset-name"><h3>The specified character encoding name
1572      <code><var>{value}</var></code> is different from the actual document
1573      character encoding <code><var>{text}</var></code>.</h3>
1574        <p>The specified character encoding name is different from
1575        the character encoding of the document.  The document
1576        is non‐conforming.</p>
1577      </div>
1578    
1579    <div class="section" id="mismatched-charset-name-not-checked"><h3>Whether the specified character encoding name
1580      <code><var>{value}</var></code> matches to the actual character encoding
1581      name cannot be checked since the input is not a byte stream.</h3></div>
1582    
1583    <div class="section" id="mode:syntax-error"><h3>The attribute value is not a valid mode
1584      name.</h3></div>
1585    
1586    <div class="section" id="nninteger:out-of-range"><h3>The specified value is out of range.</h3></div>
1587    
1588    <div class="section" id="nninteger:syntax-error"><h3>The attribute value is not a non‐negative
1589      integer.</h3></div>
1590    
1591    <div class="section" id="no-referenced-map"><h3>The <code>usemap</code> attribute references
1592      no image map.</h3></div>
1593    
1594    <div class="section" id="no-referenced-menu"><h3>The <code>contextmenu</code> attribute references
1595      no menu.</h3></div>
1596    
1597    <div class="section" id="no-referenced-header-cell"><h3>There is no table header cell whose <code>id</code>
1598      is <code><var>{value}</var></code> in the same table.</h3></div>
1599    
1600    <div class="section" id="refresh:syntax-error"><h3>the specified value is not a valid as part
1601      of a <code>Refresh</code> pragma.</h3></div>
1602    
1603    <div class="section" id="repeat:syntax-error"><h3>The attribute value is not an integer or
1604      a string <code>template</code>.</h3></div>
1605    
1606    <div class="section" id="reserved-browsing-context-name"><h3>Browsing context name
1607      <code><var>{@}</var></code> is reserved.</h3>
1608        <p>The specified browsing context name is reserved.
1609        The document is non-conforming.</p>
1610    
1611        <p>Names of browsing contexts starting with <code>_</code>
1612        (<code>U+005F</code> <code class="charname">LOW LINE</code>)
1613        are reserved so that it must not be used.</p>
1614    
1615        <p>Old version of HTML, non-HTML markup languages, and
1616        Web browsers define or implements special reserved
1617        browsing context names <code>_blank</code>,
1618        <code>_main</code>, and <code>_replace</code>.
1619        However, they are <em>not</em> conforming attribute values.</p>
1620      </div>
1621    
1622    <div class="section" id="Reserved-Prefixes-and-Namespace-Names:Name"><h3>Namespace name <code><var>{text}</var></code>
1623      is reserved and cannot be used for an arbitrary prefix.</h3></div>
1624    
1625    <div class="section" id="Reserved-Prefixes-and-Namespace-Names:Prefix"><h3>Namespace prefix <code><var>{text}</var></code>
1626      is reserved and cannot be used for an arbitrary namespace name.</h3></div>
1627    
1628    <div class="section" id="link-type:proposed"><h3>Link type <code><var>{value}</var></code>
1629      is proposed but not accepted yet; it <em>should not</em> be
1630      used until it has been accepted.</h3>
1631        <p>The link type is in the <i>proposed</i> status; it
1632        <em>should not</em> be used until it has been
1633        accepted.</p>
1634    
1635        <p><strong>Warning</strong>: The data served to the
1636        conforming checker might be out of date; it might have already
1637        been accepted or rejected.  The document might or might not be
1638        conforming depending on the status.  See WHATWG Wiki
1639        for the latest information.</p>
1640      </div>
1641    
1642    <div class="section" id="sizes:syntax-error"><h3>The specified value <code><var>{value}</var></code>
1643      is not a valid value.</h3></div>
1644    
1645    <div class="section" id="space-in-ID"><h3>White space characters are not allowed
1646      in the <code>id</code> attribute.</h3></div>
1647    
1648    <div class="section" id="template:not-template"><h3>The node referenced by the <code>template</code>
1649      attribute is not a template.</h3></div>
1650    
1651    <div class="section" id="window-name:empty"><h3>Browsing context name must not be empty.</h3></div>
1652    
1653    <div class="section" id="window-name:reserved"><h3>Browsing context name
1654      <code><var>{value}</var></code> is reserved.</h3></div>
1655    
1656    <div class="section" id="word-not-allowed"><h3>The word <code><var>{value}</var></code> is not
1657      allowed in this attribute.</h3></div>
1658    
1659    <div class="section" id="XML-1.0-NCName:syntax-error"><h3>The specified value is not a legal XML Namespaces
1660      1.0 <code>NCName</code>.</h3></div>
1661    
1662    <div class="section" id="xml:lang-ne-lang"><h3>The value of the <code>xml:lang</code> attribute
1663      is different from the value of the <code>lang</code> attribute.</h3>
1664        <p>The value of the <code>xml:lang</code> attribute (either the
1665        <code>lang</code> attribute in the <code>xml</code> (i.e.
1666        <code>http://www.w3.org/XML/1998/namespace</code>) namespace, or
1667        the <code>xml:lang</code> attribute in no namespace) for the element has
1668        different value than that of the <code>lang</code> attribute in no
1669        namespace.</p>
1670    
1671        <p>For historical reason, there are two attributes applicable to HTML
1672        elements to specify language information of an element: <code>lang</code>
1673        and <code>xml:lang</code>.  In HTML documents, only <code>lang</code>
1674        attribute in no namespace is allowed and take effect; the
1675        <code>xml:lang</code> attribute in no namespace is ignored in HTML
1676        documents.  In XHTML documents, both <code>lang</code> and
1677        <code>xml:lang</code> attributes are allowed.</p>
1678    
1679        <p>In general, <em>only the <code>lang</code> attribute</em> need to be
1680        specified for an element.</p>
1681    
1682        <p>If both <code>lang</code> and <code>xml:lang</code> attributes are
1683        specified on the same element, their values must be the same value.</p>
1684      </div>
1685    
1686  </section>  </section>
1687    
1688  <section id="table-model-errors">  <section id="table-model-errors">
1689  <h2>Table Model Errors</h2>  <h2>Table Model Errors</h2>
1690    
1691  <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
1692      multiple cells.</h3></div>
1693    
1694    <div class="section" id="colspan-creates-column-with-no-anchored-cell"><h3>This <code>colspan</code> attribute
1695    results in creating a table column that does not contain    results in creating a table column that does not contain
1696    any cell anchored to it.</h3></div>    any cell anchored to it.</h3></div>
1697    
1698  <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>
1699    
1700    <div class="section" id="table:no-cell-in-last-row"><h3>The table has no cell (<code>td</code> or
1701    <code>th</code>) in the last row.</h3></div>    <code>th</code>) in the last row.</h3></div>
1702    
1703    <div class="section" id="table:rowspan-extends-table"><h3>This <code>rowspan</code> attribute
1704      results in creating a table row that does not contain
1705      any cell anchored to it.</h3>
1706        <p>The <code>rowspan</code> attribute value of the cell
1707        is so specified that it extends a table in the row axis.
1708        However, the extended row does not contain any cell by itself.
1709        The document is non-conforming.</p>
1710    
1711        <p>For example, the table below is non-conforming:
1712          <pre class="html bad example">
1713    <code>&lt;table&gt;
1714    &lt;tbody&gt;
1715    &lt;tr&gt;&lt;td rowspan=2&gt;&lt;/td&gt;&lt;/tr&gt;
1716    &lt;/tbody&gt;
1717    &lt;/table&gt;</code></pre>
1718        ... since the second row contains only
1719        a cell that spans between first and second rows.</p>
1720      </div>
1721    
1722    <div class="section" id="row-with-no-anchored-cell"><h3>This row has no anchored cell.</h3></div>
1723    
1724    <div class="section" id="rowspan-creates-row-with-no-anchored-cell"><h3>This <code>rowspan</code> attribute
1725      results in creating a table row that does not contain
1726      any cell anchored to it.</h3></div>
1727    
1728    
1729  </section>  </section>
1730    
1731  <section id="imt-warnings">  <section id="imt-warnings">
1732  <h2>Internet Media Type Warnings</h2>  <h2>Internet Media Type Errors</h2>
1733    
1734    <div class="section" id="boundary:syntax-error"><h3>The specified value is not a valid value
1735      as a multipart boundary.</h3></div>
1736    
1737  <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
1738      for the attribute <code>e4x</code>.</h3></div>
1739    
1740  <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,
1741    subtype is used.</h3></div>    <code><var>{value}</var></code>, is syntactically not a valid
1742      attribute name.</h3></div>
1743    
1744    <div class="section" id="IMT:composite"><h3>The specified media type is a composite
1745      type, which is not allowed in this context.</h3></div>
1746    
1747    <div class="section" id="IMT:limited-use-subtype"><h3>An Internet Media Type whose intended usage
1748      is limited use, <code><var>{value}</var></code> is used.</h3></div>
1749    
1750    <div class="section" id="IMT:syntax-error"><h3>The specified value is not an Internet Media
1751      Type.</h3></div>
1752    
1753    <div class="section" id="IMT:obsolete-parameter"><h3>An obsolete parameter
1754      <code><var>{value}</var></code> is used.</h3></div>
1755    
1756    <div class="section" id="IMT:obsolete-subtype"><h3>An obsolete Internet Media Type
1757      <code><var>{value}</var></code> is used.</h3>
1758        <p>The specified Internet Media Type is registered with its intended
1759        usage as <i>OBSOLETE</i>.</p>
1760        
1761        <dl class="swtich">
1762        <dt>Media type <code>text/ecmascript</code></dt>
1763          <dd>Media type <code>text/ecmascript</code> is obsoleted in
1764          favor of <code>application/ecmascript</code>.  Note that
1765          <em><code>text/javascript</code></em> would be the better alternative
1766          in many cases.</dd>
1767        <dt>Media type <code>text/javascript</code></dt>
1768          <dd>Media type <code>text/javascript</code> is obsoleted by
1769          <abbr>IETF</abbr> with backward incompatible alternate
1770          <code>application/javascript</code> for architectural
1771          purity.<!-- @@ ref? -->  Those who prefer reality to academic
1772          purity <em>may ignore</em> this warning.</dd>
1773        </dl>
1774      </div>
1775    
1776    <div class="section" id="IMT:parameter-missing"><h3>Parameter <code><var>{text}</var></code> have to
1777      be specified for the Internet Media Type
1778      <code><var>{value}</var></code>.</h3></div>
1779    
1780    <div class="section" id="IMT:parameter-not-allowed"><h3>Parameter <code><var>{value}</var></code> is not
1781      allowed for this Internet Media Type.</h3></div>
1782    
1783    <div class="section" id="IMT:private-subtype"><h3>Use of a private Internet Media Type
1784      <code><var>{value}</var></code> is not encouraged.</h3></div>
1785    
1786    <div class="section" id="IMT:private-type"><h3>Use of a private type
1787      <code><var>{value}</var></code> is not encouraged.</h3></div>
1788    
1789    <div class="section" id="IMT:subtype-syntax-error"><h3>Value <code><var>{value}</var></code> is
1790      syntactically not a valid subtype value of an Internet Media Type.</h3></div>
1791    
1792    <div class="section" id="IMT:type-syntax-error"><h3>Value <code><var>{value}</var></code> is
1793      syntactically not a valid type.</h3></div>
1794    
1795    <div class="section" id="IMT:unknown-parameter"><h3>An unknown parameter <code><var>{value}</var></code>
1796      is used.  The conformance checker cannot determine whether use of this
1797      parameter is valid or not.</h3></div>
1798    
1799    <div class="section" id="IMT:unknown-subtype"><h3>An unknown Internet Media Type
1800      <code><var>{value}</var></code> is used.  At the time of the update of
1801      the conformance checker's Internet Media Type database, the subtype is
1802      not reigstered to the IANA registry.  The subtype, however, might be
1803      registerd to the IANA registry thereafter.  Please consult the IANA
1804      registry.</h3></div>
1805    
1806    <div class="section" id="IMT:unregistered-subtype"><h3>Use of an Internet Media Type
1807      <code><var>{value}</var></code> is not encouraged since it is not
1808      part of the IANA registry.</h3></div>
1809    
1810    <div class="section" id="IMT:unregistered-type"><h3>Use of a type
1811      <code><var>{value}</var></code> is not encouraged since it is not
1812      a standardized type.</h3></div>
1813    
1814  <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
1815      is not allowed here.</h3></div>
1816    
1817  </section>  </section>
1818    
1819  <section id="uri-errors">  <section id="uri-errors">
1820  <h2>URI (or IRI) Errors</h2>  <h2>URL Errors</h2>
1821    
1822  <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
1823      IRI.</h3></div>
1824    
1825  </section>  <div class="section" id="syntax-error:iriref3987"><h3>The specified value is syntactically not an IRI
1826      reference.</h3>
1827        <p>The specified value does not satisfy the syntactical requirements
1828        for IRI references.  The document is non-conforming.</p>
1829    
1830        <p>Possible causes:
1831          <ul>
1832          <li>The string might contain one or more white space characters.
1833          Especially, the <code> </code> (<code>U+0020</code>
1834          <code class="charname">SPACE</code>) character cannot be
1835          used in IRI references.</li>
1836          </ul>
1837        </p>
1838      </div>
1839    
1840    <div class="section" id="syntax-error:rdfuriref"><h3>The specified value is syntactically not an RDF
1841      URI reference.</h3></div>
1842    
1843    <div class="section" id="syntax-error:uri2396"><h3>The specified value is syntactically not a
1844      URI according to RFC 2396.</h3></div>
1845    
1846  <section id="uri-warnings">  <div class="section" id="syntax-error:uri3986"><h3>The specified value is syntactically not a
1847  <h2>URI (or IRI) Warnings</h2>    URI.</h3></div>
1848    
1849  <div class="section should" id="s:URI::dot-segment"><h3>Dot-segment (<code>.</code> or  <div class="section" id="URL:address-format"><h3>URL host address format
1850    <code>..</code>) should not occur in an absolute reference.</h3>    <code><var>{text}</var></code> is not defined.</h3></div>
1851    
1852    <div class="section" id="URL:default-port"><h3>Default port number should be omitted.</h3></div>
1853    
1854    <div class="section" id="URL:dot-segment"><h3>A dot-segment (<code>.</code> or
1855      <code>..</code>) occurs in an absolute reference.</h3>
1856      <p>Dot-segment (<code>.</code> or <code>..</code>) should      <p>Dot-segment (<code>.</code> or <code>..</code>) should
1857      not occur in an absolute reference.</p>      not occur in an absolute reference.</p>
1858    
# Line 438  Web Document Conformance Checker (BETA)< Line 1863  Web Document Conformance Checker (BETA)<
1863      canonical form before it has been published.</p>      canonical form before it has been published.</p>
1864    </div>    </div>
1865    
1866  <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>
1867    <code>/</code>.</h3></div>  
1868    <div class="section" id="URL:empty-path"><h3>The URL does not end with
1869      a <code>/</code> character.</h3></div>
1870    
1871    <div class="section" id="URL:empty-port"><h3>The port component of the URL is empty.</h3></div>
1872    
1873    <div class="section" id="URL-fragment-not-allowed"><h3>The fragment component of the URL is not
1874      allowed.</h3></div>
1875    
1876    <div class="section" id="URL:long-host"><h3>The host component of the URL
1877      is too long.</h3></div>
1878    
1879    <div class="section" id="URL:lowercase-hexadecimal-digit"><h3>A lowercase hexadecimal digit is used
1880      in percent-encoding.</h3>
1881        <p>The hexadecimal digit in percent-encoding string in the IRI
1882        is in lowercase.  Though the IRI <em>is</em> conforming,
1883        it should be in uppercase.</p>
1884      </div>
1885    
1886    <div class="section" id="URL:non-DNS-host"><h3>The host component of the URL
1887      is not a DNS host name.</h3></div>
1888    
1889    <div class="section" id="URL:non-UTF-8-host"><h3>The host component of the URL
1890      is not encoded in UTF-8.</h3></div>
1891    
1892    <div class="section" id="URL:password"><h3>Password should not be included in a URL
1893      for the security.</h3></div>
1894    
1895    <div class="section" id="URL:percent-encoded-unreserved"><h3>An unreserved character is
1896      percent-encoded.</h3>
1897        <p>An unreserved character is percent-encoded in the IRI.
1898        Though it <em>is</em> conforming, it should be in the
1899        decoded (or bare) form.</p>
1900      </div>
1901    
1902    <div class="section" id="URL:uppercase-host"><h3>The host <code><var>{value}</var></code>
1903      should be spelt in lowercase.</h3></div>
1904    
1905    <div class="section" id="URL:uppercase-scheme-name"><h3>URL scheme name is in uppercase.</h3>
1906        <p>The scheme part of the IRI is written in uppercase letter.</p>
1907    
1908        <p>Uppercase scheme names are not required to be processed
1909        correctly.</p>
1910    <!-- @@
1911     RFC 3986 3.1.
1912     > Although schemes are case-
1913       insensitive, the canonical form is lowercase and documents that
1914       specify schemes must do so with lowercase letters.
1915    
1916     > An implementation ... should only produce lowercase scheme names for
1917       consistency.
1918    -->
1919      </div>
1920    
1921    </section>
1922    
1923    <section id="mq-errors">
1924    <h2>Media Query Errors</h2>
1925    
1926    <div class="section" id="mq-syntax-error"><h3>The specified value has a syntax error as a
1927      media query.</h3></div>
1928    
1929    <div class="section" id="unknown-media-type"><h3>Media type <code><var>{value}</var></code> is
1930      not supported by the conformance checker.</h3></div>
1931    
1932    </section>
1933    
1934    <section id="selectors-errors">
1935    <h2>Selectors Errors</h2>
1936    
1937    <div class="section" id="an+b-not-closed"><h3>Argument list of the pseudo-class is
1938      not closed by a <code>)</code> character.</h3></div>
1939    
1940    <div class="section" id="ab+b-not-integer"><h3>Numbers in the argument
1941      <code><var>a</var>n+<var>b</var></code> have to be integers.</h3></div>
1942    
1943    <div class="section" id="an+b-syntax-error"><h3>Argument <code><var>a</var>n+<var>b</var></code> is
1944      syntactically incorrect.</h3></div>
1945    
1946    <div class="section" id="attr-selector-not-closed"><h3>Attribute selector is not closed by
1947      a <code>]</code> character.</h3></div>
1948    
1949    <div class="section" id="lang-selector-not-closed"><h3>Argument list of the <code>:lang</code>
1950      selector is not closed by a <code>)</code> character.</h3></div>
1951    
1952    <div class="section" id="namespace-prefix:not-declared"><h3>Namespace prefix <code><var>{value}</var></code>
1953      is not declared.</h3></div>
1954    
1955    <div class="section" id="no-attr-local-name"><h3>Attribute local name is missing.</h3></div>
1956    
1957    <div class="section" id="no-attr-match"><h3>Attribute matching operator (e.g.
1958      <code>=</code>) is missing.</h3></div>
1959    
1960    <div class="section" id="no-attr-name"><h3>Attribute name is missing.</h3></div>
1961    
1962    <div class="section" id="no-attr-namespace-separator"><h3>Attribute namespace wildcard <code>*</code>
1963      is not followed by a <code>|</code> character.</h3></div>
1964    
1965    <div class="section" id="no-attr-value"><h3>Attribute value is missing.</h3></div>
1966    
1967    <div class="section" id="no-class-name-selector"><h3>Class name is missing.</h3></div>
1968    
1969    <div class="section" id="no-combinator"><h3>Combinator is missing.</h3></div>
1970    
1971    <div class="section" id="no-contains-string"><h3>No string is specified in the argument
1972      list of the <code>:-manakai-contains</code> pseudo-class
1973      selector.</h3></div>
1974    
1975    <div class="section" id="no-lang-tag"><h3>Language tag argument is missing.</h3></div>
1976    
1977    <div class="section" id="no-local-name-selector"><h3>Local name part of the type selector (or
1978      <code>*</code> for the universal selector) is missing.</h3></div>
1979    
1980    <div class="section" id="no-pseudo-class-name"><h3>Pseudo-class name is missing.</h3></div>
1981    
1982    <div class="section" id="no-pseudo-element-name"><h3>Pseudo-element name is missing.</h3></div>
1983    
1984    <div class="section" id="no-sss"><h3>Sequence of simple selectors is
1985      expected.</h3></div>
1986    
1987    <div class="section" id="not-not-closed"><h3>Argument list of the <code>:not</code> selector
1988      is not closed by a <code>)</code> character.</h3></div>
1989    
1990    <div class="section" id="ss-after-pseudo-element"><h3>Simple selector is not allowed after a
1991      pseudo element.</h3></div>
1992    
1993    <div class="section" id="unknown-pseudo-class"><h3>Pseudo-class <code>:<var>{value}</var></code>
1994      is not supported by the conformance checker.</h3></div>
1995    
1996    <div class="section" id="unknown-pseudo-element"><h3>Pseudo-element <code>::<var>{value}</var></code>
1997      is not supported by the conformance checker.</h3></div>
1998    
1999    </section>
2000    
2001    <section id="css-errors">
2002    <h2>CSS Errors</h2>
2003    
2004    <div class="section" id="at-rule-not-allowed"><h3>An <code>@<var>{text}</var></code> rule is not
2005      allowed here.</h3></div>
2006    
2007    <div class="section" id="at-rule-syntax-error"><h3>The <code>@<var>{text}</var></code> rule is
2008      syntactically incorrect.</h3></div>
2009    
2010    <div class="section" id="block-not-closed"><h3>Block is not closed before the end of
2011      file.</h3></div>
2012    
2013    <div class="section" id="CSS-duplication"><h3>Component <code>&lt;<var>{text}</var>&gt;</code> is
2014      already specified.</h3></div>
2015    
2016    <div class="section" id="CSS-cursor-hand"><h3>Value <code>hand</code> is not valid as
2017      <code>&lt;'cursor'&gt;</code>.</h3></div>
2018    
2019    <div class="section" id="CSS-syntax-error"><h3>Specified value is syntactically not a correct
2020      <code>&lt;<var>{text}</var>&gt;</code>.</h3></div>
2021    
2022    <div class="section" id="no-declaration-block"><h3>No declaration block is found after a group of
2023      selectors.</h3></div>
2024    
2025    <div class="section" id="no-property-colon"><h3>A <code>:</code> character is missing after
2026      a property name.</h3></div>
2027    
2028    <div class="section" id="no-property-name"><h3>Property name is expected.</h3></div>
2029    
2030    <div class="section" id="no-property-semicolon"><h3>A <code>;</code> character is missing at the
2031      end of the property.</h3></div>
2032    
2033    <div class="section" id="priority-syntax-error"><h3>Priority part of the declaration is syntactically
2034      incorrect.</h3></div>
2035    
2036    <div class="section" id="unknown-at-rule"><h3>The <code>@<var>{value}</var></code> rule is
2037      not supported by the conformance checker.</h3></div>
2038    
2039    <div class="section" id="unknown-property"><h3>Property <code><var>{value}</var></code> is
2040      not supported by the conformance checker.</h3></div>
2041    
2042    </section>
2043    
2044    <section id="cache-manifest-errors">
2045    <h2>Cache Manifest Errors</h2>
2046    
2047    <div class="section" id="both-in-entries-and-whitelist"><h3>This URL is found both in the explicit or
2048      fallback entries and in the online whitelist.</h3></div>
2049    
2050    <div class="section" id="different-origin-from-manifest"><h3>The specified URL has different origin from
2051      the manifest.</h3></div>
2052    
2053    <div class="section" id="different-scheme-from-manifest"><h3>The scheme component of the URL is
2054      different from that of the manifest URL.  The URL is ignored.</h3></div>
2055    
2056    <div class="section" id="duplicate-oc-namespace"><h3>This oppotunistic caching namespace is already
2057      specified.</h3></div>
2058    
2059    <div class="section" id="no-fallback-entry-URL"><h3>Fallback entry URL is missing.</h3></div>
2060    
2061    <div class="section" id="not-manifest"><h3>This document is not a cache manifest.</h3>
2062        <p>The specified document is <em>not</em> a cache manifest.
2063        The document is non-conforming.</p>
2064    
2065        <p>An entity labeled as Internet media type
2066        <code>text/cache-manifest</code> must contain a cache manifest.</p>
2067    
2068        <p>A cache manifest must start with a line whose content is
2069        <code class="manifest example">CACHE MANIFEST</code>
2070        (exactly one space character between
2071        <code>CACHE</code> and <code>MANIFEST</code>).</p>
2072      </div>
2073    
2074    <div class="section" id="same-as-manifest-URL"><h3>This URL is same as the manifest URL.</h3></div>
2075    
2076    </section>
2077    
2078    <section id="information">
2079    <h2>Stability Information</h2>
2080    
2081    <div class="section" id="deprecated:attr"><h3>This attribute is deprecated.</h3></div>
2082    
2083    <div class="section" id="deprecated:element"><h3>This element is deprecated.</h3></div>
2084    
2085    <div class="section" id="status:cr:element"><h3>This element is in the
2086      <strong>call for implementation</strong> stage.</h3>
2087        <p>The element is in the call for implementation stage.</p>
2088        
2089        <p>Usually, using the element is safe.  However, it is a new feature
2090        so that it might not be implemented correctly.  If it is found that
2091        the feature is hard or impossible to implement, the feature
2092        might be revised, or in some case it might be dropped.</p>
2093    
2094        <p>Elements defined by Atom 1.0 (IETF Proposed Standard), and XBL 2.0
2095        (W3C Candidate Recommendation) belong to this class.</p>
2096      </div>
2097    
2098    <div class="section" id="status:lc:element"><h3>This element is in the <strong>last
2099      call for comments</strong> stage.</h3>
2100        <p>The element is in the last call for comments stage.</p>
2101        
2102        <p>The element is relatively mature, though the standardization
2103        is not done yet.  It may be used for experiments.  Since it is a new
2104        feature, it might not be implemented correctly or at all.  If it is
2105        found that the feature is hard or impossible to implement, the feature
2106        might be revised or might be dropped.</p>
2107    
2108        <p>Elements defined by Web Forms 2.0 as well as some elements
2109        defined by HTML5 belong to this class.</p>
2110      </div>
2111    
2112    <div class="section" id="status:wd:element"><h3>This element is documented in a <strong>working
2113      draft</strong>.</h3>
2114        <p>The element is documented in a working or editor's draft
2115        and not yet completed.</p>
2116        
2117        <p>The element should not be used for any practical purpose.
2118        The feature might be drastically changed later or might be
2119        entirely removed.</p>
2120    
2121        <p>Most of new elements defined by HTML5 belong to this class.</p>
2122      </div>
2123    
2124    <div class="section" id="status:non-standard:element"><h3>This element is <strong>not part of any
2125      standard</strong> the conformance checker knows.</h3>
2126        <p>The element is not part of any standard or draft the conformance
2127        checker is aware of.</p>
2128        
2129        <p>The element should not be used for any practical purpose unless
2130        there is really a standard that defines the element.</p>
2131      </div>
2132    
2133    <div class="section" id="status:cr:attr"><h3>This attribute is in the
2134      <strong>call for implementation</strong> stage.</h3>
2135        <p>The attribute is in the call for implementation stage.</p>
2136        
2137        <p>Usually, using the attribute is safe.  However, it is a new feature
2138        so that it might not be implemented correctly.  If it is found that
2139        the feature is hard or impossible to implement, the feature
2140        might be revised, or in some case it might be dropped.</p>
2141      </div>
2142    
2143    <div class="section" id="status:lc:attr"><h3>This attribute is in the <strong>last
2144      call for comments</strong> stage.</h3>
2145        <p>The attribute is in the last call for comments stage.</p>
2146        
2147        <p>The attribute is relatively mature, though the standardization
2148        is not done yet.  It may be used for experiments.  Since it is a new
2149        feature, it might not be implemented correctly or at all.  If it is
2150        found that the feature is hard or impossible to implement, the feature
2151        might be revised or might be dropped.</p>
2152      </div>
2153    
2154    <div class="section" id="status:wd:attr"><h3>This attribute is documented in a <strong>working
2155      draft</strong>.</h3>
2156        <p>The attribute is documented in a working or editor's draft
2157        and not yet completed.</p>
2158        
2159        <p>The attribute should not be used for any practical purpose.
2160        The feature might be drastically changed later or might be
2161        entirely removed.</p>
2162      </div>
2163    
2164    <div class="section" id="status:non-standard:attr"><h3>This attribute is <strong>not part of any
2165      standard</strong> the conformance checker knows.</h3>
2166        <p>The attribute is not part of any standard or draft the conformance
2167        checker is aware of.</p>
2168        
2169        <p>The attribute should not be used for any practical purpose unless
2170        there is really a standard that defines the attribute.</p>
2171      </div>
2172    </section>
2173    
2174    <section id="langtag-errors">
2175    <h2>Language Tag Errors</h2>
2176    
2177    <div class="section" id="langtag:extension:duplication"><h3>There is another extension subtag
2178      <code><var>{value}</var></code>.</h3></div>
2179    
2180    <div class="section" id="langtag:illegal"><h3>Subtag <code><var>{value}</var></code> is
2181      syntactically invalid.</h3></div>
2182    
2183    <div class="section" id="langtag:language:case"><h3>It is a good practice to represent ISO 639-1
2184      language code <code><var>{value}</var></code> in lowercase.</h3></div>
2185    
2186    <div class="section" id="langtag:language:mul"><h3>Langauge tag <code>mul</code> should not be
2187      used.</h3></div>
2188    
2189    <div class="section" id="langtag:language:nosemantics"><h3>No semantics is defined for language subtag
2190      <code><var>{value}</var></code>.</h3></div>
2191    
2192    <div class="section" id="langtag:language:syntax"><h3>The language subtag <code><var>{value}</var></code>
2193      is syntactically invalid.</h3></div>
2194    
2195    <div class="section" id="langtag:language:und"><h3>Langauge tag <code>und</code> should not be
2196      used.</h3></div>
2197    
2198    <div class="section" id="langtag:private"><h3>It would be better if a private use language
2199      tag (<code><var>{value}</var></code>) is not used.</h3></div>
2200    
2201    <div class="section" id="langtag:privateuse:syntax"><h3>Private use subtag <code><var>{value}</var></code>
2202      is syntactically invalid.</h3></div>
2203    
2204    <div class="section" id="langtag:region:case"><h3>It is a good practice to represent ISO 3166
2205      country code <code><var>{value}</var></code> in uppercase.</h3></div>
2206    
2207    <div class="section" id="langtag:region:nosemantics"><h3>No semantics is defined for region subtag
2208      <code><var>{value}</var></code>.</h3></div>
2209    
2210    <div class="section" id="langtag:region:private"><h3>Use of private use country code
2211      <code><var>{value}</var></code> is not allowed.</h3></div>
2212    
2213    </section>
2214    
2215    <section id="rdfxml-errors">
2216    <h2>RDF/XML Errors</h2>
2217    
2218    <div class="section" id="bad-rdf-namespace"><h3>The namespace URI of an element that
2219      represents an RDF concept must be
2220      <code>http://www.w3.org/1999/02/22-rdf-syntax-ns#</code>.</h3></div>
2221    
2222    <div class="section" id="duplicate-rdf-id"><h3>The specified value is already used as an
2223      ID.</h3></div>
2224    
2225    <div class="section" id="duplicate-unqualified-attr"><h3>Both unqualified attribute and namespace‐qualified
2226      RDF attribute are specified, which is not allowed.</h3></div>
2227    
2228    <div class="section" id="parse-type-other"><h3>An invalid value is specified to
2229      the <code>parseType</code> attribute.</h3></div>
2230    
2231    <div class="section" id="second-node-element"><h3>There is another element, such that
2232      this element is not allowed.</h3></div>
2233    
2234    <div class="section" id="unqualified-attr"><h3>Unqualified attribute is not allowed.</h3></div>
2235    
2236    <div class="section" id="unqualified-rdf-attr"><h3>RDF attribute should be
2237      namespace‐qualified.</h3></div>
2238    
2239  </section>  </section>
2240    
2241  <section id="unsupported-messages">  <section id="unsupported-messages">
2242  <h2><i>Unsupported</i> Messages</h2>  <h2><i>Unsupported</i> Messages</h2>
2243    
2244  <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
2245    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
2246      <p>The conformant checker does not support the attribute.    might not be conforming</em>.</h3>
2247        <p>The conformant checker does not support the element.
2248      It cannot determine whether the document is conforming or not.</p>      It cannot determine whether the document is conforming or not.</p>
2249    </div>    </div>
2250    
2251  <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
2252    conformance checker; <em>it might or might not be conforming</em>.</h3>    <code><var>{local-name}</var></code> of element
2253      <p>The conformant checker does not support the element.    <code><var>{element-local-name}</var></code> is not supported;
2254      <em>it might or might not be conforming</em>.</h3>
2255        <p>The conformant checker does not support the attribute.
2256      It cannot determine whether the document is conforming or not.</p>      It cannot determine whether the document is conforming or not.</p>
2257    </div>    </div>
2258    
2259  <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
2260    or registered at the time of the release of the conformance checker;    standardized or registered at the time of the release of the conformance
2261    <em>it is non-conforming unless it has now been registered</em>.</h3>    checker; <em>it is non-conforming unless it now has been
2262      registered</em>.</h3>
2263      <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.
2264      Some common link types are defined in the HTML5 specification.      Some common link types are defined in the HTML5 specification.
2265      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 2270  Web Document Conformance Checker (BETA)<
2270      The link type might have been added to the registry since then.      The link type might have been added to the registry since then.
2271      In such case it might be conforming.  Otherwise, the      In such case it might be conforming.  Otherwise, the
2272      document is non-conforming.</p>      document is non-conforming.</p>
2273    
2274        <dl>
2275        <dt>Link types <code>shortcut icon</code></dt>
2276            <dd>Link type <code>shortcut</code> is not registered.
2277            Use only <code>icon</code> for linking to so-called favicon.</dd>
2278        </dl>
2279      </div>
2280    
2281    <div class="section" id="event-handler"><h3>Conformance checking for event handler attribute
2282      is not supported; <em>it might or might not be conforming.</em></h3></div>
2283    
2284    <div class="section" id="media-query"><h3>Conformance checking for media query
2285      is not supported; <em>it might or might not be conforming.</em></h3></div>
2286    
2287    <div class="section" id="addr-spec-not-supported"><h3>Conformance checking for an <code>addr-spec</code>
2288      is not supported; <em>it might or might not be conforming.</em></h3></div>
2289    
2290    <div class="section" id="XML-script-lang"><h3>Conformance checking for script
2291      language <code><var>{text}</var></code> is not supported;
2292      <em>it might or might not be conforming.</em></h3></div>
2293    
2294    <div class="section" id="XML-style-lang"><h3>Conformance checking for style
2295      language <code><var>{text}</var></code> is not supported;
2296      <em>it might or might not be conforming.</em></h3></div>
2297    
2298    <div class="section" id="atom|content-not-supported"><h3>Conformance checking for an Atom
2299      <code>content</code> element with <code>type</code>
2300      <code><var>{text}</var></code> is not supported.</h3></div>
2301    
2302    <div class="section" id="help-not-available"><h3>No more information is available.</h3>
2303        <p>No more information is available for this topic.</p>
2304    </div>    </div>
2305    
2306  </section>  </section>
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2514    
2515    
2516    <div class="section" id="Error-level-m"><h3><a href="../error-description#Error-level-m" rel="help"><em class="rfc2119">MUST</em>‐level
2517            error</a></h3>
2518        <p>A violation to a hard requirement of the specification.
2519        The document is non‐conforming.</p>
2520      </div>
2521    
2522    <div class="section" id="Error-level-s"><h3><a href="../error-description#Error-level-s" rel="help"><em class="rfc2119">SHOULD</em>‐level
2523            error</a></h3>
2524        <p>A violation to a requirement of the specification.
2525        The violation might be legitimize in some case.  Otherwise,
2526        the document is non‐conforming.</p>
2527      </div>
2528    
2529    <div class="section" id="Error-level-w"><h3><a href="../error-description#Error-level-w" rel="help">Warning</a></h3>
2530        <p>A warning is an advice from the conformance checker
2531        to avoid solving a problem in a confusing or possibly wrong way.
2532        It does not affect to the conformance of the document, and
2533        may sometimes be inappropriate.</p>
2534      </div>
2535    
2536    <div class="section" id="Error-level-i"><h3><a href="../error-description#Error-level-i" rel="help">Information</a></h3>
2537        <p>An informational message just provides an additional information
2538        on the feature used in the document or the status of the retrieval
2539        or so on.
2540        It does not affect to the conformance of the document.</p>
2541      </div>
2542    
2543    <div class="section" id="Error-level-u"><h3><a href="../error-description#Error-level-u" rel="help">Not
2544          supported</a></h3>
2545        <p>Some feature that is not supported by the conformance checker
2546        is used in the document.</p>
2547      </div>
2548    
2549  <section id="license">  <section id="license">
2550  <h2>License of This Document</h2>  <h2>License of This Document</h2>
2551    
2552  <p>Copyright 2007 <a href="http://suika.fam.cx/~wakaba/who?">Wakaba</a></p>  <p>Copyright <time>2007</time>‐<time>2008</time>
2553  <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>
2554    <code class="mail">&lt;<a href="mailto:[email protected]">[email protected]</a>&gt;</code>.</p>
2555    
2556    <p>This document is free software; you can redistribute it
2557  and/or modify it under the same terms as Perl itself.</p>  and/or modify it under the same terms as Perl itself.</p>
2558  </section>  </section>
2559    

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