Semantic elements and attributes improve communication. For details please consult the semantics document.
The semantics of an
href does not provide a clear,
direct, explicit, and strong semantic for a long
Programmatic determinability aids accessibility.
A normal link below or near an image or in another part of the document is not programmatically determinable. Without programmatically determinability no explicit relationship exists to indicate that a long description has anything to do with an image.
The fact is
a href only works on a limited
subset of use cases as it is impossible for one link to take a user
to two locations. An
href is not programmatically determinable when an image
already has a link, which is mapped to go to another page or a
<img> elements on the web
that need long descriptions not to have a parent
<a> element mapped to a different task
unrelated to a long description is unrealistic, i.e., a thumbnail <img> that links to a larger .jpg as evidenced by sites such as the National Institute of Dental and Craniofacial Research.
For example, if an image already has a link that takes the user to another page (i.e., a logo image that links to a home page, one cartoon in a series of cartoon images that links to the next comic strip page, a thumbnail image that links to a larger version of an image, etc.), it is impractical and most times nonsensical for the destination page to shoehorn in a long description. It would provide a confusing and inferior user experience.
Removing the possibility for direct, dual, programmatic access
to both a long description via
longdesc and a separate
a href on an
<img> element would be
(a) needless authoring impediment, (b) a step backwards for HTML,
and (c) a barrier to providing accessible content. Including
longdesc in HTML5 affords authors a way to provide
a href as well as an accessible
programmatically determinable long description.
href forces a
visual encumbrance on sighted users unless additional code (in
the form of CSS or
hidden) were added in order to hide
the visual indicator. Please refer to the Cascading Style
hidden documents for
details of why using these techniques is a bad idea.
No evidence has been presented that an
produces more accessible content for long descriptions.