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HTML5 Lacks a Way to Programmatically-Determine Missing Text Alternatives

Bug Number


Bug Title

HTML5 Lacks a Way to Programmatically-Determine Missing Text Alternatives

Spec Section

Bug Description

Tools need a way to programmatically determine [3] where images whose contents are not known to be detected and labeled as such.

Outcomes of Fixing the Bug

  • A "missing" attribute would provide a practical method of detection, handling, and future improvement.
  • Possibilities for crowdsourcing exist with the addition of a "missing" attribute It should be reasonably easy to maintain a hash of images with @missing and the obtain value(s) submitted for them. We would need a canonical URI (or in HTML5, an 'origin') for the document and an ID for the image, but if we had a service (either local or remote) that accepted the URI and its @alt value, then users of AT could associate the values as needed. The worst case is that nothing is returned. (The second-worst case is that it's a bogus value, but the owner of the document could manage submitted @alt content.) The pointer to where to send this information could be in a <link> element, and it could be a standard HTTP request, or a transaction using the HTML5 Database object. It could be hosted locally, or by a third party. This idea would get around one of the biggest problems with around images: that we can see something is wrong with someone else's content, but can't do anything about it. With this method people who know what they're doing could directly impact the accessibility of another organization's content. It also helps image gallery sites since the image creator or anyone who views the image could propose usable @alt with an extremely low-bandwidth solution. If this method is used then we'd have to specify @missing, and that any image with that attribute also needs an ID, or they wouldn't be associable by the UA/AT. Then we'd need to specify the @rel attribute for the <link> to the mechanism for associating the @alt.
  • Would be valid and in accord with Accessibility Coordination Group's "Consensus Resolutions on Text alternatives in HTML 5". [4]

Attribute name

If it is not too long, "notextalternative" could be a suitable name instead of "missing" for this attribute. The image could be missing any one of text alternatives in the set of valid options for conformance checkers.


HTML5 Issue and Change Proposal

This is associated with HTML TRACKER ISSUE-31:

Change Proposal - Replace img Guidance for Conformance Checkers: