$0 element cannot be
- inserted between head and body elements.<$0>
+ is not allowed after the end tag </html>.A start tag occurs after the head element is closed
- but before the body element is opened.
+
The start or end tag of an element appears after the
+ html element has been closed. The document is
+ non-conforming.
Any content of the document other than comments
+ must be put into the html element.
<$0>
+ is not allowed after the end tag </body>.The start or end tag of an element appears after the
+ body element has been closed. The document is
+ non-conforming.
Any content of the document other than head
+ contents and comments must be put into the body
+ element.
& character must
+ introduce a reference.An & (U+0026
+ AMPERSAND) character which
+ is not part of any reference appears in the input stream.
The document is non-conforming.
The & character must
+ be the first character of a reference:
+
&entity-name;&#d;&#xh;To represent & as a data character, use
+ named entity reference:
+
&</ string is not followed
+ by a tag name.There is a < (U+003C
+ LESS-THAN SIGN) character
+ immediately followed by a / (U+005F
+ SOLIDUS) character, which is not part
+ of any end tag, in the input stream. The document
+ is non-conforming.
The </ sequence immediately followed
+ by an EOF is
+ interpreted as a string data of </.
The </ sequence as string data must
+ be escaped as:
+
</< character is not followed
+ by tag name or by a ! character.A < (U+003C
+ LESS-THAN SIGN) character which is not part
+ of any markup appears in the input stream.
The < character as a data character must
+ be escaped as:
+
<&#.An & (U+0026
+ AMPERSAND) character immediately
+ followed by a # (U+0023
+ NUMBER SIGN) character which
+ is not part of any reference appears in the input stream.
+ The document is non-conforming.
The string &# must be the first two characters
+ of a reference:
+
&#d;&#xh;To represent &# as data characters, use
+ a named entity reference for the & character:
+
&#&#x.The string &#x or &#X which
+ is not part of any reference appears in the input stream.
+ The document is non-conforming.
The string &#x or &#X must
+ be the first three characters of a hexadecimal reference:
+
&#xh;To represent &#x as data characters, use
+ a named entity reference for the & character:
+
&#x</ string is not followed
+ by a tag name.There is a < (U+003C
+ LESS-THAN SIGN) character
+ immediately followed by a / (U+005F
+ SOLIDUS) character, which is not part
+ of any end tag, in the input stream. The document
+ is non-conforming.
The </ sequence not followed by a
+ tag name is parsed as an opening of bogus comment.
The </ sequence as string data must
+ be escaped as:
+
</-- sequence
+ in a comment.There is a - (U+002D
+ HYPHEN-MINUS) character
+ at the end of the comment or a -- sequence
+ in the comment. The document is non-conforming.
Comments cannot contain a string --, as in XML.
+ Unlike SGML, there cannot be more than one comments
+ (where comment is an SGML term) in the comment
+ declaration.
$0.Attributes must be unique in an element. Specifying - attributes with same name more than once is non-conforming.
+There are more than one attributes with the same + name in a tag. The document is non-conforming.
The motion attribute is not part of the HTML standard.
Use img element with animation GIF instead.
/>) cannot be
used for this element.The void element syntax /> syntax can only be
+
Void element syntax (/>) must not be used
+ for the element. The document is non-conforming.
The void element syntax can only be
used for base, link, meta,
hr, br, img,
embed, param, area,
- col, and input elements.
- For any other elements, using that syntax is non-conforming.
col, and input elements.
- Unlike XML, the void element syntax (/>) has
+
Note that, unlike in XML, the void element syntax has no effect in HTML.
<?...?>) cannot be used.Processing instructions (<?...?>),
+ including XML declaration (<?xml ...?>)
+ and XML style sheet PI
+ (<xml-stylesheet ...?>), are not allowed
+ in the HTML syntax. The document is non-conforming.
If it is necessary to embed a processing instruction + in the HTML document, you must use the XML syntax instead.
+ +In the HTML syntax, XML declaration is not necessary.
+ +Instead of XML style sheet,
+ PIs, you must
+ use the HTML link element whose rel
+ attribute is set to stylesheet (or
+ alternate stylesheet for an aleternate style sheet).
Web browsers will parse processing instructions as bogus + comments. Some legacy Web browsers, such as IE:mac and + some mobile browsers, will display processing instructions + as string.
+$0 element cannot be
+ inserted between head and body elements.A start tag appears after the head element is closed
+ but before the body element is opened.
+ The document is non-conforming.
DOCTYPE appears after any
+ element or data character has been seen.A DOCTYPE appears after any element or data character
+ has been seen. The document is non-conforming.
The DOCTYPE must be placed before any
+ tag, reference, or data character. Only white space characters
+ and comments can be inserted before the DOCTYPE.
HTML a elements cannot be nested.
+ The document is non-conforming.
In the HTML syntax, a start tag of the a
+ implies the end tag of any opening a element.
<$0>
+ is not allowed in a body element.The start or end tag of an element, which
+ cannot be a descendant of body element, appears
+ in the input stream while the body element has been opened.
+ The document is non-conforming.
<head>
+ is not allowed in the head element.There is a start tag <head> in the
+ <head> element. The document is non-conforming.
In an HTML document there must not be more than
+ one head element, therefore no more than one
+ start tag <head> can appear in the input stream.
<$0>
+ is not allowed in a table element.The start or end tag of an element, which
+ cannot be a child of table element, appears
+ in the input stream while the table element has been opened
+ but no other element has been opened. The document is non-conforming.
In table, only table related elements
+ are allowed; any other element must be contained in
+ td or th element to form
+ a part of the table, or caption element to create
+ a table caption.
table.A data character appears in table. The document
+ is non-conforming.
In table, only table related elements
+ are allowed; any other element and data character must be contained in
+ td or th element to form
+ a part of the table, or caption element to create
+ a table caption.
tr
+ element is missing.Start tag of a tr element, which is not
+ optional, is missing. The document is non-conforming.
In a table section, a <tr> start tag
+ must occur before any <td> or
+ <th> start tag. Though the HTML5 parser
+ implies the <tr> start tag before
+ these start tags, it must be explicitly specified.
DOCTYPE.The document does not start with a DOCTYPE.
+ The document is non-conforming.
An HTML document must start by a DOCTYPE:
+
<!DOCTYPE HTML>Only white space characters and comments are allowed
+ before the DOCTYPE.
$0 is not
+ closed.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.
+<html> tag is not
+ the first start tag.There is a start tag of the html element
+ that it not the first start tag in the input stream.
+ The document is non-conforming.
In an HTML document, there cannot be more than one
+ html element and therefore there cannot be
+ more than one <html> tag. In addition,
+ nothing can be placed before the <html> tag
+ except a DOCTYPE, white space characters,
+ and comments.
The document contains a DOCTYPE declaration
+ that is different from HTML5 DOCTYPE (i.e.
+ <!DOCTYPE HTML>). The document is non-conforming.
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.
+$0 is not
+ opened.An end tag appears though no element with the same name + has been opened. The document is non-conforming.
+ +For any end tag in HTML document, there must be a + corresponding start tag.
+A data character occurs where it is not allowed in this +
A data character appears where it is not allowed in this context. The document is non-conforming.
Possible causes: -
a or span)A data character cannot be a child
- of certain sectioning elements such as body,
- section, and blockquote.
Any inline-level content must be put
- in e.g. paragraph element such as p.
div or hn)Though some elements such as div,
- li, and td allow
- either one 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 p.
A data character cannot be a child
+ of certain sectioning elements such as body,
+ section, and blockquote.
Any inline-level content must be put
+ in e.g. paragraph element such as p.
Though some elements such as div,
+ li, and td allow
+ either one 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 p.
The content model of the element is so defined that it
must contain a $0 child element.
- Without such an element, the document is non-conforming.
For example:
th element as a child of this element.
The tr element must contain at least one
- td or th child element. Without
- such an element, the document is non-conforming.
td or th child element. The document
+ is non-conforming.
An element occurs where it is not allowed. The document +
An element appears where it is not allowed. The document is non-conforming.
+Note: The conformance checker does + not support form elements yet.
+Possible causes: -
a or span)a, progress, or imgAn inline-level element cannot be a child
of certain sectioning elements such as body,
section, and blockquote.
Any inline-level content must be put
in e.g. paragraph element such as p.
div or hn)div, hn, or
+ sectionThough some elements such as div,
li, and td allow
either one 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 p.
html elementnoscript elementnoscript element is allowed only in the context
+ where a block-level or inline-level content is expected
+ and in the head element.
+ It cannot be used in e.g. ul, table,
+ or select.html element
+ that is the root element of an XHTML documentIn an XHTML document, the root html
element must have an xmlns attribute
whose value is set to
@@ -158,28 +578,380 @@
DOCTYPE declaration.
-not HTML5;parse-error;This document is written in an old version of HTML.
-not closed;parse-error;Element $0 is not closed.
-unmatched end tag;parse-error;Element $0 is not opened.
-
-table:no cell in last row;table-model-error;The table has no cell (td or th) in the last row.
-
-s:IMT:obsolete subtype;should;An obsolete subtype is used.
-s:IMT:private subtype;should;A private (x- or x.) subtype is used.
-s:IMT:unregistered subtype;should;The subtype is not registered to IANA.
+$0
+ element before this element.There must be an element before another element, but there + is not. The document is non-conforming.
+ +For example, there must be a dt element
+ before any dd element.
$0
+ is not specified.A required attribute is not specified. The document + is non-conforming.
+ +Some attribute is defined as required.
+ For example, any img element must have
+ alt and src attributes specified.
+ Without required attributes specified, user agents
+ cannot provide the full functionality of the element
+ to the user.
xml:lang attribute is not
+ allowed in HTML document.The xml:lang attribute is not allowed in
+ HTML document. The document is non-conforming.
The lang attribute in the null
+ namespace for HTML elements is defined as conforming only for
+ XML document.
To specify natural language information in HTML document,
+ use lang attribute instead.
XHTML 1.0 Appendix C was encouraged to specify both
+ lang and xml:lang attributes with
+ the same value. Such a duplication has no effect in practice.
+ Use only one of lang (in HTML) or xml:lang (in
+ XML).
charset attribute is not
+ allowed in XML document.The charset attribute of a
+ meta element is not allowed in XML document.
+ The document is non-conforming.
To specify the character encoding used for serialization, + if necessary, use XML declaration instead: +
<?xml version="1.0" encoding="encoding-name"?>lang attribute is not
+ allowed in XML document.The HTML lang attribute is not allowed in
+ XML document. The document is non-conforming.
The lang attribute in null
+ namespace for HTML elements is defined as conforming only for
+ HTML document.
To specify natural language information in XML document,
+ use xml:lang attribute instead.
xmlns attribute
+ in the null namespace is not allowed in
+ XHTML document. The document is non-conforming.The xmlns attribute in the null
+ namespace is not allowed in XHTML document.
This error should not occur in conformance-checking + static documents.
+{@} is not one
+ of them.$0
+ cannot be specified for this element.The specified link type cannot be used for the element. + The document is non-conforming.
+ +Link types are associated with limited set of elements. + They cannot be used with other elements.
+ +For example, link type bookmark
+ can be used with a or area element,
+ while it cannot be used with link element.
$0
+ is non-conforming.The specified link type is non-conforming, and therefore + the document is non-conforming.
+ +contentsindex.copyrightlicense.homeindex.startfirst.tocindex.{@} is reserved.The specified browsing context name is reserved. + The document is non-conforming.
+ +Names of browsing contexts starting with _
+ (U+005F LOW LINE)
+ are reserved so that it must not be used.
Old version of HTML, non-HTML markup languages, and
+ Web browsers define or implements special reserved
+ browsing context names _blank,
+ _main, and _replace.
+ However, they are not conforming attribute values.
$0
+ is proposed but not accepted yet; it should not be
+ used until it has been accepted.The link type is in the proposed status; it + should not be used until it has been + accepted.
+ +Warning: The data served to the + conforming checker might be out of date; it might have already + been accepted or rejected, depending on which the document + might be conforming or non-conforming. See WHATWG Wiki + for the latest information.
+colspan attribute
+ results in creating a table column that does not contain
+ any cell anchored to it.td or
+ th) in the last row.rowspan attribute
+ results in creating a table row that does not contain
+ any cell anchored to it.The rowspan attribute value of the cell
+ is so specified that it extends a table in the row axis.
+ However, the extended row does not contain any cell by itself.
+ The document is non-conforming.
For example, the table below is non-conforming: +
<table>
+<tbody>
+<tr><td rowspan=2></td></tr>
+</tbody>
+</table>{@}: An obsolete
+ subtype is used.{@}: A private
+ (x- or x.) subtype is used.{@}: The subtype is
+ not registered to IANA.The specified value does not satisfy the syntactical requirements + for IRI references. The document is non-conforming.
+ +Possible causes: +
(U+0020
+ SPACE) character cannot be
+ used in IRI references.. or
+ ..) should not occur in an absolute reference.Dot-segment (. or ..) should
+ not occur in an absolute reference.
In relative references, dot-segments are used to represent
+ the current (.) or the parent (..)
+ hierarchy of the path. Though they are also allowed
+ in absolute references, it should be resolved to the
+ canonical form before it has been published.
/.The hexadecimal digit in percent-encoding string in the IRI + is in lowercase. Though the IRI is conforming, + it should be in uppercase.
+An unreserved character is percent-encoded in the IRI. + Though it is conforming, it should be in the + decoded (or bare) form.
+The scheme part of the IRI is written in uppercase letter.
-s:URI::empty path;should;This IRI should explicitly end with/.
-m:URI::syntax error;must;This IRI is not syntactically valid.
+ Uppercase scheme names are not required to be processed + correctly.
+ +$0 is not standardized
- or registered at the time of the release of the conformance checker;
- it is non-conforming unless it has now been registered.$0 is not
+ standardized or registered at the time of the release of the conformance
+ checker; it is non-conforming unless it has now been
+ registered.The rel attribute is defined as a list of link types.
Some common link types are defined in the HTML5 specification.
@@ -217,8 +990,49 @@
$0 is not supported;
+ it might or might not be conforming.$0 is not supported;
+ it might or might not be conforming.