test/html-webhacc/error-description-source.xml

<!DOCTYPE html>
<html xmlns="http://www.w3.org/1999/xhtml"
    xmlns:d="http://suika.fam.cx/~wakaba/archive/2007/wdcc-desc/"
    id="error-description">
<head>
<title xml:lang="en">Description of Errors &#x2014; 
Web Document Conformance Checker (BETA)</title>
<link rel="stylesheet" href="cc-style"/>
<link rel="license" href="#license"/>
</head>
<body>
<h1>Description of Errors</h1>

<section id="html5-tokenize-error">
<h2>HTML5 Parse Errors in Tokenization Stage</h2>

<d:item name="after html"
    class="parse-error">
  <d:message xml:lang="en">Tag <code>&lt;<var>$0</var>&gt;</code>
  is not allowed after the end tag <code>&lt;/html></code>.</d:message>
  <d:desc xml:lang="en">
    <p>The start or end tag of an element appears after the
    <code>html</code> element has been closed.  The document is
    non-conforming.</p>

    <p>Any content of the document other than comments
    must be put into the <code>html</code> element.</p>
  </d:desc>
</d:item>

<d:item name="bare ero"
    class="tokenize-error">
  <d:message xml:lang="en">The <code>&amp;</code> character must
  introduce a reference.</d:message>
  <d:desc xml:lang="en">
    <p>An <code>&amp;</code> (<code>U+0026</code>
    <code class="charname">AMPERSAND</code>) character which
    is not part of any reference appears in the input stream.
    The document is non-conforming.</p>

    <p>The <code>&amp;</code> character must
    be the first character of a reference:
      <dl>
      <dt>Named entity reference</dt>
          <dd><pre class="html example"><code>&amp;<var>entity-name</var>;</code></pre>
          where <var>entity-name</var> is the name of the
          character entity to be referenced.</dd>
      <dt>Numeric character reference</dt>
          <dd><pre class="html example"><code>&amp;#<var>d</var>;</code></pre>
          where <var>d</var> is the decimal representation of
          the code position of the character to be referenced.</dd>
      <dt>Hexadecimal character reference</dt>
          <dd><pre class="html example"><code>&amp;#x<var>h</var>;</code></pre>
          where <var>h</var> is the hexadecimal representation
          of the code position of the character to be referenced.</dd>
      </dl>
    </p>

    <p>To represent <code>&amp;</code> as a data character, use
    named entity reference:
      <pre class="html example"><code>&amp;amp;</code></pre>
    </p>
  </d:desc>
</d:item>

<d:item name="bare stago"
    class="tokenize-error">
  <d:message xml:lang="en">A <code>&lt;</code> character is not followed
  by tag name or by a <code>!</code> character.</d:message>
  <d:desc xml:lang="en">
    <p>A <code>&lt;</code> (<code>U+003C</code> <code class="charname">LESS-THAN
    SIGN</code>) character which is not part of any markup appears
    in the input stream.</p>

    <p>The <code>&lt;</code> character as a data character must
    be escaped as:
    <pre class="html example"><code>&lt;lt;</code></pre>
    </p>
  </d:desc>
</d:item>

<d:item name="bare nero"
    class="tokenize-error">
  <d:message xml:lang="en">The decimal representation of the code position
  of a character must be specified after <code>&amp;#</code>.</d:message>
  <d:desc xml:lang="en">
    <p>An <code>&amp;</code> (<code>U+0026</code>
    <code class="charname">AMPERSAND</code>) character immediately
    followed by a <code>#</code> (<code>U+0023</code>
    <code>NUMBER SIGN</code>) character which
    is not part of any reference appears in the input stream.
    The document is non-conforming.</p>

    <p>The string <code>&amp;#</code> must be the first two characters
    <code>NUMBER SIGN</code>) character must be the first two characters
    of a reference:
      <dl>
      <dt>Numeric character reference</dt>
          <dd><pre class="html example"><code>&amp;#<var>d</var>;</code></pre>
          where <var>d</var> is the decimal representation of
          the code point of the character to be referenced.</dd>
      <dt>Hexadecimal character reference</dt>
          <dd><pre class="html example"><code>&amp;#x<var>h</var>;</code></pre>
          where <var>h</var> is the hexadecimal representation
          of the code point of the character to be referenced.</dd>
      </dl>
    </p>

    <p>To represent <code>&amp;#</code> as data characters, use
    named entity reference:
      <pre class="html example"><code>&amp;amp;#</code></pre>
    </p>
  </d:desc>
</d:item>

<d:item name="bare hcro"
    class="tokenize-error">
  <d:message xml:lang="en">The hexadecimal representation of the code position
  of a character must be specified after <code>&amp;#x</code>.</d:message>
  <d:desc xml:lang="en">
   <p>The string <code>&amp;#x</code> or <code>&amp;#X</code> which
   is not part of any reference appears in the input stream.
    The document is non-conforming.</p>

    <p>The string <code>&amp;#x</code> or <code>&amp;#X</code> must
    be the first three characters of a hexadecimal reference:
      <pre class="html example"><code>&amp;#x<var>h</var>;</code></pre>
    where <var>h</var> is the hexadecimal representation
    of the code point of the character to be referenced.</p>

    <p>To represent <code>&amp;#x</code> as data characters, use
    named entity reference:
      <pre class="html example"><code>&amp;amp;#x</code></pre>
    </p>
  </d:desc>
</d:item>

<d:item name="dash in comment"
    class="tokenize-error">
  <d:message xml:lang="en">There is a <code>--</code> sequence
  in a comment.</d:message>
  <d:desc xml:lang="en">
    <p>There is a <code>-</code> (<code>U+002D</code>
    <code class="charname">HYPHEN-MINUS</code>) character 
    at the end of the comment or a <code>--</code> sequence
    in the comment.  The document is non-conforming.</p>

    <p>Comments cannot contain a string <code>--</code>, as in XML.
    Unlike SGML, there cannot be more than one comments
    (where <i>comment</i> is an SGML term) in the comment
    declaration.</p>
  </d:desc>
</d:item>

<d:item name="duplicate attribute"
    class="tokenize-error">
  <d:message xml:lang="en">There are two attributes with same name.</d:message>
  <d:desc xml:lang="en">
    <p>There are more than one attributes with the same
    name in a tag.  The document is non-conforming.</p>

    <p>The <code>motion</code> attribute is not part of the HTML standard.
    Use <code>img</code> element with animation GIF instead.</p>
  </d:desc>
</d:item>

<d:item name="nestc"
    class="tokenize-error">
  <d:message xml:lang="en">Void element syntax (<code>/></code>) cannot be
  used for this element.</d:message>
  <d:desc xml:lang="en">
    <p>Void element syntax (<code>/></code>) must not be used
    for the element.  The document is non-conforming.</p>

    <p>The void element syntax can only be
    used for <code>base</code>, <code>link</code>, <code>meta</code>,
    <code>hr</code>, <code>br</code>, <code>img</code>, 
    <code>embed</code>, <code>param</code>, <code>area</code>,
    <code>col</code>, and <code>input</code> elements.</p>

    <p>Note that, unlike in XML, the void element syntax has
    no effect in HTML.</p>
  </d:desc>
</d:item>

</section>

<section id="html5-parse-errors">
<h2>HTML5 Parse Errors in Tree Construction Stage</h2>

<d:item name="after head"
    class="parse-error">
  <d:message xml:lang="en">The <code><var>$0</var></code> element cannot be
  inserted between <code>head</code> and <code>body</code> elements.</d:message>
  <d:desc xml:lang="en">
    <p>A start tag appears after the <code>head</code> element is closed
    but before the <code>body</code> element is opened.
    The document is non-conforming.</p>
  </d:desc>
</d:item>

<d:item name="DOCTYPE in the middle"
    class="parse-error">
  <d:message xml:lang="en">A <code>DOCTYPE</code> appears after any
  element or data character has been seen.</d:message>
  <d:desc xml:lang="en">
    <p>A <code>DOCTYPE</code> appears after any element or data character
    has been seen.  The document is non-conforming.</p>
    
    <p>The <code>DOCTYPE</code> must be placed before any
    tag, reference, or data character.  Only white space characters
    and comments can be inserted before the <code>DOCTYPE</code>.</p>
  </d:desc>
</d:item>

<d:item name="in body"
    class="parse-error">
  <d:message xml:lang="en">Tag <code>&lt;<var>$0</var>&gt;</code>
  is not allowed in <code>body</code>.</d:message>
  <d:desc xml:lang="en">
    <p>The start or end tag of an element, which 
    cannot be a descendant of <code>body</code> element, appears
    in the input stream while the <code>body</code> element has been opened.
    The document is non-conforming.</p>
  </d:desc>
</d:item>

<d:item name="in table"
    class="parse-error">
  <d:message xml:lang="en">Tag <code>&lt;<var>$0</var>&gt;</code>
  is not allowed in <code>table</code>.</d:message>
  <d:desc xml:lang="en">
    <p>The start or end tag of an element, which
    cannot be a child of <code>table</code> element, appears
    in the input stream while the <code>table</code> element has been opened
    but no other element has been opened.  The document is non-conforming.</p>

    <p>In <code>table</code>, only table related elements
    are allowed; any other element must be contained in
    <code>td</code> or <code>th</code> element to form 
    a part of the table, or <code>caption</code> element to create
    a table caption.</p>
  </d:desc>
</d:item>

<d:item name="in table:#character"
    class="parse-error">
  <d:message xml:lang="en">Data character is not allowed in 
  <code>table</code>.</d:message>
  <d:desc xml:lang="en">
    <p>A data character appears in <code>table</code>.  The document
    is non-conforming.</p>

    <p>In <code>table</code>, only table related elements
    are allowed; any other element and data character must be contained in
    <code>td</code> or <code>th</code> element to form 
    a part of the table, or <code>caption</code> element to create
    a table caption.</p>
  </d:desc>
</d:item>

<d:item name="missing start tag:tr"
    class="parse-error">
  <d:message xml:lang="en">Start tag of <code>tr</code>
  element is missing.</d:message>
  <d:desc>
    <p>Start tag of a <code>tr</code> element, which is <em>not</em>
    optional, is missing.  The document is non-conforming.</p>

    <p>In a table section, a <code>&lt;tr></code> start tag
    must occur before any <code>&lt;td></code> or
    <code>&lt;th></code> start tag.  Though the HTML5 parser
    implies the <code>&lt;tr></code> start tag before
    these start tags, it must be explicitly specified.</p>
  </d:desc>
</d:item>

<d:item name="no DOCTYPE"
    class="parse-error">
  <d:message xml:lang="en">This document does not start with the
  <code>DOCTYPE</code>.</d:message>
  <d:desc>
    <p>The document does not start with a <code>DOCTYPE</code>.
    The document is non-conforming.</p>

    <p>An HTML document must start by a <code>DOCTYPE</code>:
      <pre class="html example"><code>&lt;!DOCTYPE HTML></code></pre>
    </p>

    <p>Only white space characters and comments are allowed
    before the <code>DOCTYPE</code>.</p>
  </d:desc>
</d:item>

<d:item name="not closed"
    class="parse-error">
  <d:message xml:lang="en">Element <code><var>$0</var></code> is not
  closed.</d:message>
  <d:desc>
    <p>End tag of an element is not found before, for example,
    an end tag of another element appears or
    the end of the document.  The document is non-conforming.</p>
  </d:desc>
</d:item>

<d:item name="not HTML5"
    class="parse-error">
  <d:message xml:lang="en">This document is written in an old version of 
  HTML.</d:message>
  <d:desc xml:lang="en">
    <p>The document contains a <code>DOCTYPE</code> declaration
    that is different from HTML5 <code>DOCTYPE</code> (i.e. <code>&lt;!DOCTYPE 
    HTML&gt;</code>).  The document is non-conforming.</p>

    <p>The document might or might not be conformant to
    some version of HTML.  However, conformance to any HTML
    specification other than HTML5 provides for no practical
    convenience, since Web borwsers will parse any
    HTML document (roughly) as defined in HTML5.</p>
  </d:desc>
</d:item>

<d:item name="unmatched end tag"
    class="parse-error">
  <d:message xml:lang="en">Element <code><var>$0</var></code> is not
  opened.</d:message>
  <d:desc>
    <p>An end tag appears though no element with the same name
    has been opened.  The document is non-conforming.</p>

    <p>For any end tag in HTML document, there must be a
    corresponding start tag.</p>
  </d:desc>
</d:item>

</section>

<section id="element-content-model-errors">
<h2>Element Content Model Errors</h2>

<d:item name="character not allowed"
    class="content-model-error">
  <d:message xml:lang="en">Data character is not allowed in this
  context.</d:message>
  <d:desc xml:lang="en">
    <p>A data character appears where it is not allowed in this
    context.  The document is non-conforming.</p>

    <p>Possible causes:
      <dl>
      <dt>If the erred element is an inline-level element (such
      as <code>a</code> or <code>span</code>)</dt>
          <dd><p>A data character cannot be a child
          of certain sectioning elements such as <code>body</code>,
          <code>section</code>, and <code>blockquote</code>.</p>

          <p>Any inline-level content must be put
          in e.g. paragraph element such as <code>p</code>.</p></dd>
      <dt>If the erred element is a block-level element (such as
      <code>div</code> or <code>h<var>n</var></code>)</dt>
          <dd><p>Though some elements such as <code>div</code>,
          <code>li</code>, and <code>td</code> allow
          <em>either one</em> of block-level or inline-level content
          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>
    </p>
  </d:desc>
</d:item>

<d:item name="child element missing"
    class="content-model-error">
  <d:message xml:lang="en">There must be a <code><var>$0</var></code>
  element as a child of this element.</d:message>
  <d:desc xml:lang="en">
    <p>The content model of the element is so defined that it
    must contain a <code><var>$0</var></code> child element.
    The document is non-conforming.</p>

    <p>For example:
      <ul>
      <li>The <code>head</code> element must contain exactly one
      <code>title</code> child element.</li>
      <li><a href="#child-element-missing:td%7Cth">The <code>tr</code>
      element must contain one or more <code>td</code> or <code>th</code>
      child element.</a></li>
      </ul>
    </p>
  </d:desc>
</d:item>

<d:item name="child element missing:td|th"
    class="content-model-error">
  <d:message xml:lang="en">There must be a <code>td</code>
  or <code>th</code> element as a child of this element.</d:message>
  <d:desc xml:lang="en">
    <p>The <code>tr</code> element must contain at least one
    <code>td</code> or <code>th</code> child element.  The document
    is non-conforming.</p>
  </d:desc>
</d:item>

<d:item name="element not allowed"
    class="content-model-error">
  <d:message xml:lang="en">This element is not allowed in this 
  context.</d:message>
  <d:desc xml:lang="en">
    <p>An element appears where it is not allowed.  The document
    is non-conforming.</p>

    <p><strong>Note</strong>: The conformance checker does
    <em>not</em> support form elements yet.</p>

    <p>Possible causes:
      <dl>
      <dt>If the erred element is an inline-level element (such
      as <code>a</code> or <code>span</code>)</dt>
          <dd><p>An inline-level element cannot be a child
          of certain sectioning elements such as <code>body</code>,
          <code>section</code>, and <code>blockquote</code>.</p>

          <p>Any inline-level content must be put
          in e.g. paragraph element such as <code>p</code>.</p></dd>
      <dt>If the erred element is a block-level element (such as
      <code>div</code> or <code>h<var>n</var></code>)</dt>
          <dd><p>Though some elements such as <code>div</code>,
          <code>li</code>, and <code>td</code> allow
          <em>either one</em> of block-level or inline-level content
          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>
      <dt>If the erred element is the root <code>html</code> element</dt>
          <dd><p>In an XHTML document, the root <code>html</code>
          element must have an <code>xmlns</code> attribute
          whose value is set to 
          <code>http://www.w3.org/1999/xhtml</code>.</p></dd>
      </dl>
    </p>
  </d:desc>
</d:item>

</section>

<section id="attribute-errors">
<h2>Attribute Errors</h2>

<d:item name="attribute missing"
    class="attribute-error">
  <d:message xml:lang="en">Required attribute <code><var>$0</var></code>
  is not specified.</d:message>
  <d:desc>
    <p>A required attribute is not specified.  The document
    is non-conforming.</p>

    <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.
    Without required attributes specified, user agents 
    cannot provide the full functionality of the element
    to the user.</p>
  </d:desc>
</d:item>

<d:item name="in HTML:xml:lang"
    class="attribute-error">
  <d:message xml:lang="en">The <code>xml:lang</code> attribute is not 
  allowed in HTML document.</d:message>
  <d:desc>
    <p>The <code>xml:lang</code> attribute is not allowed in
    HTML document.  The document is non-conforming.</p>

    <p>The <code>lang</code> attribute in the <code>null</code>
    namespace for HTML elements is defined as conforming <em>only</em> for
    XML document.</p>

    <p>To specify natural language information in HTML document,
    use <code>lang</code> attribute instead.</p>
    <!-- @@ ISSUE: xml:lang in non-HTML element in DOM5 HTML created
         from an HTML document? -->
  </d:desc>
</d:item>

<d:item name="in XML:charset"
    class="attribute-error">
  <d:message xml:lang="en">The <code>charset</code> attribute is not 
  allowed in XML document.</d:message>
  <d:desc>
    <p>The <code>charset</code> attribute of a
    <code>meta</code> element is not allowed in XML document.
    The document is non-conforming.</p>

    <p>To specify the character encoding used for serialization,
    if necessary, use XML declaration instead:
      <pre class="xml example"><code>&lt;?xml version="1.0" encoding="<var>encoding-name</var>"?></code></pre>
    </p>
  </d:desc>
</d:item>

<d:item name="in XML:lang"
    class="attribute-error">
  <d:message xml:lang="en">The <code>lang</code> attribute is not 
  allowed in XML document.</d:message>
  <d:desc>
    <p>The HTML <code>lang</code> attribute is not allowed in
    XML document.  The document is non-conforming.</p>

    <p>The <code>lang</code> attribute in <code>null</code>
    namespace for HTML elements is defined as conforming <em>only</em> for
    HTML document.</p>

    <p>To specify natural language information in XML document,
    use <code>xml:lang</code> attribute instead.</p>
  </d:desc>
</d:item>

<d:item name="in XML:xmlns"
    class="attribute-error">
  <d:message xml:lang="en">The <code>xmlns</code> attribute 
  in the <code>null</code> namespace is not allowed in
  XHTML document.  The document is non-conforming.</d:message>
  <d:desc>
    <p>The <code>xmlns</code> attribute in the <code>null</code>
    namespace is not allowed in XHTML document.</p>

    <p>This error should not occur in conformance-checking 
    static documents.</p>
  </d:desc>
</d:item>

</section>

<section id="attribute-value-errors">
<h2>Attribute Value Errors</h2>

<d:item name="enumerated:invalid"
    class="attribute-value-error">
  <d:message xml:lang="en">This attribute only allow a limited set of 
  values and the specified value is not one of them.</d:message>
</d:item>

<d:item name="duplicate ID"
    class="attribute-value-error">
  <d:message xml:lang="en">This identifier has already been
  assigned to another element.</d:message>
  <!-- @@ <id=a xml:id=a>? -->
</d:item>

<d:item name="link type:bad-context"
    class="attribute-value-error">
  <d:message xml:lang="en">The link type <code><var>$0</var></code>
  cannot be specified for this element.</d:message>
  <d:desc xml:lang="en">
    <p>The specified link type cannot be used for the element.
    The document is non-conforming.</p>

    <p>Link types are associated with limited set of elements.
    They cannot be used with other elements.</p>

    <p>For example, link type <code>bookmark</code>
    can be used with <code>a</code> or <code>area</code