<$0>
is not allowed after the end tag </html>.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.
& 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;
where entity-name is the name of the
character entity to be referenced.
&#d;
where d is the decimal representation of
the code position of the character to be referenced.
&#xh;
where h is the hexadecimal representation
of the code position of the character to be referenced.To represent & as a data character, use
named entity reference:
&
< 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;
where d is the decimal representation of
the code point of the character to be referenced.
&#xh;
where h is the hexadecimal representation
of the code point of the character to be referenced.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;
where h is the hexadecimal representation
of the code point of the character to be referenced.
To represent &#x as data characters, use
a named entity reference for the & character:
&#x
-- 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.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.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.
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 appears where it is not allowed in this context. The document is non-conforming.
Possible causes:
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.
$0
element as a child of this element.The content model of the element is so defined that it
must contain a $0 child element.
The document is non-conforming.
For example:
head element must contain exactly one
title child element.tr
element must contain one or more td or th
child element.td
or th element as a child of this element.The tr element must contain at least one
td or th child element. The document
is non-conforming.
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, 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, 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.
noscript 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
http://www.w3.org/1999/xhtml.
$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>
... is non-conforming, since the second row contains only
a cell that spans the first and the second rows.
{@}: 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.
Uppercase scheme names are not required to be processed correctly.
The conformant checker does not support the attribute. It cannot determine whether the document is conforming or not.
The conformant checker does not support the element. It cannot determine whether the document is conforming or not.
$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.
Additional link types can be registered to the WHATWG Wiki.
use of any other link type is non-conforming.
The specified link type is not part of the standard or registry when the database used by the conformance cheker is created. The link type might have been added to the registry since then. In such case it might be conforming. Otherwise, the document is non-conforming.
$0 is not supported;
it might or might not be conforming.$0 is not supported;
it might or might not be conforming.Copyright 2007 Wakaba
This library is free software; you can redistribute it and/or modify it under the same terms as Perl itself.