Features listed in this section will trigger warnings in conformance checkers.
Authors should not specify an http-equiv attribute in the
Content
Language state on a meta element. The lang attribute should be used instead.
Authors should not specify a border attribute on an
img element. If the attribute is present, its value
must be the string "0". CSS should be used
instead.
Authors should not specify a language attribute on a
script element. If the attribute is present, its value
must be an ASCII case-insensitive match for the string
"JavaScript" and either the type attribute must be omitted or
its value must be an ASCII case-insensitive match for
the string "text/javascript". The attribute
should be entirely omitted instead (with the value "JavaScript", it has no effect), or replaced with use
of the type attribute.
Authors should not specify the name attribute on a
elements. If the attribute is present, its value must not be the
empty string and must neither be equal to the value of any of the
IDs in the element's home
subtree other than the element's own ID, if any, nor be equal to the value of
any of the other name attributes on
a elements in the element's home
subtree. If this attribute is present and the element has an
ID, then the attribute's value must
be equal to the element's ID. In
earlier versions of the language, this attribute was intended as a
way to specify possible targets for fragment identifiers in URLs. The id
attribute should be used instead.
In the HTML syntax, specifying a DOCTYPE that is an obsolete permitted DOCTYPE will also trigger a warning.
The summary
attribute, defined in the table section, will also
trigger a warning.
Elements in the following list are entirely obsolete, and must not be used by authors:
appletacronymUse abbr instead.
bgsoundUse audio instead.
dirUse ul instead.
frameframesetnoframesEither use iframe and CSS instead, or use server-side includes to generate complete pages with the various invariant parts merged in.
isindexUse an explicit form and text field combination instead.
listingxmpnextidUse GUIDs instead.
noembedplaintextUse the "text/plain" MIME type instead.
rbProviding the ruby base directly inside the ruby element is sufficient; the rb element is unnecessary. Omit it altogether.
strikeUse del instead if the element is marking an edit, otherwise use s instead.
basefontbigblinkcenterfontmarqueemulticolnobrspacerttuUse appropriate elements and/or CSS instead.
Where the tt element would have been used for
marking up keyboard input, consider the kbd element;
for variables, consider the var element; for computer
code, consider the code element; and for computer
output, consider the samp element.
Similarly, if the u element is being used to
indicate emphasis, consider using the em element; if
it is being used for marking up keywords, consider the
b element; and if it is being used for highlighting
text for reference purposes, consider the mark
element.
See also the text-level semantics usage summary for more suggestions with examples.
The following attributes are obsolete (though the elements are still part of the language), and must not be used by authors:
charset on a elementscharset on link elementsUse an HTTP Content-Type header on the linked resource instead.
coords on a elementsshape on a elementsmethods on a elementsmethods on link elementsUse the HTTP OPTIONS feature instead.
name on a elements (except as noted in the previous section)name on embed elementsname on img elementsname on option elementsUse the id attribute instead.
rev on a elementsrev on link elementsUse the rel
attribute instead, with an opposite term. (For example, instead of
rev="made", use rel="author".)
urn on a elementsurn on link elementsSpecify the preferred persistent identifier using the href attribute instead.
nohref on area elementsOmitting the href
attribute is sufficient; the nohref attribute is
unnecessary. Omit it altogether.
profile on head elementsWhen used for declaring which meta terms are
used in the document, unnecessary; omit it altogether, and register the names.
When used for triggering specific user agent behaviors: use
a link element instead.
version on html elementsUnnecessary. Omit it altogether.
usemap on input elementslongdesc on iframe elementslongdesc on img elementsUse a regular a element to link to the
description, or (in the case of images) use an image
map to provide a link from the image to the image's
description.
lowsrc on img elementsUse a progressive JPEG image (given in the src attribute),
instead of using two separate images.
target on link elementsUnnecessary. Omit it altogether.
scheme on meta elementsUse only one scheme per field, or make the scheme declaration part of the value.
archive on object elementsclassid on object elementscode on object elementscodebase on object elementscodetype on object elementsUse the data and type attributes to invoke plugins. To set parameters with these names
in particular, the param element can be used.
declare on object elementsRepeat the object element completely each time the resource is to be reused.
standby on object elementsOptimize the linked resource so that it loads quickly or, at least, incrementally.
type on param elementsvaluetype on param elementsUse the name and value attributes without declaring
value types.
language on script elements (except as noted in the previous section)Use the type attribute
instead.
event on script elementsfor on script elementsUse DOM Events mechanisms to register event listeners. [DOMEVENTS]
datapagesize on table elementsUnnecessary. Omit it altogether.
abbr on td and th elementsUse text that begins in an unambiguous and terse manner, and include any more elaborate text after that. The title attribute can also be useful in including more detailed text, so that the cell's contents can be made terse.
axis on td and th elementsdatasrc on a, applet, button, div, frame, iframe, img, input, label, legend, marquee, object, option, select, span, table, and textarea elementsdatafld on a, applet, button, div, fieldset, frame, iframe, img, input, label, legend, marquee, object, param, select, span, and textarea elementsdataformatas on button, div, input, label, legend, marquee, object, option, select, span, and table elementsUse script and a mechanism such as XMLHttpRequest to populate the page dynamically. [XHR]
alink on body elementsbgcolor on body elementslink on body elementsmarginbottom on body elementsmarginheight on body elementsmarginleft on body elementsmarginright on body elementsmargintop on body elementsmarginwidth on body elementstext on body elementsvlink on body elementsclear on br elementsalign on caption elementsalign on col elementschar on col elementscharoff on col elementsvalign on col elementswidth on col elementsalign on div elementscompact on dl elementsalign on embed elementshspace on embed elementsvspace on embed elementsalign on hr elementscolor on hr elementsnoshade on hr elementssize on hr elementswidth on hr elementsalign on h1—h6 elementsalign on iframe elementsallowtransparency on iframe elementsframeborder on iframe elementshspace on iframe elementsmarginheight on iframe elementsmarginwidth on iframe elementsscrolling on iframe elementsvspace on iframe elementsalign on input elementshspace on input elementsvspace on input elementsalign on img elementsborder on img elements (except as noted in the previous section)hspace on img elementsvspace on img elementsalign on legend elementstype on li elementscompact on menu elementsalign on object elementsborder on object elementshspace on object elementsvspace on object elementscompact on ol elementsalign on p elementswidth on pre elementsalign on table elementsbgcolor on table elementsborder on table elementscellpadding on table elementscellspacing on table elementsframe on table elementsrules on table elementswidth on table elementsalign on tbody, thead, and tfoot elementschar on tbody, thead, and tfoot elementscharoff on tbody, thead, and tfoot elementsvalign on tbody, thead, and tfoot elementsalign on td and th elementsbgcolor on td and th elementschar on td and th elementscharoff on td and th elementsheight on td and th elementsnowrap on td and th elementsvalign on td and th elementswidth on td and th elementsalign on tr elementsbgcolor on tr elementschar on tr elementscharoff on tr elementsvalign on tr elementscompact on ul elementstype on ul elementsbackground on body, table, thead, tbody, tfoot, tr, td, and th elementsUse CSS instead.