Delete H45 (Using longdesc)

[fstrr]

The longdesc attribute is obsolete in the HTML spec. Although there is a W3C HTML5 Image Description Extension (longdesc) document from 2015, this 2019 Memorandum Of Understanding Between W3C and WHATWG states:

"HTML and DOM shall be developed principally in the WHATWG, following WHATWG Living Standard (LS) specification process. W3C intends to give input to and endorse WHATWG Review Drafts to become W3C Recommendations, through the W3C Process from Candidate Recommendation (CR) through Proposed Recommendation (PR) to Recommendation (REC). Our Design Goal is that the W3C CR, PR, and REC, and the WHATWG Review Draft are the same document."

I have recently run new tests for longdesc support. There are some browser and screen reader combinations that support it. The longdesc attribute has never had robust support and now that it is obsolete, I believe that we should delete it as a technique.

See Issue 950 for an earlier discussion on this issue.

[lauracarlson]

cc: @chaals

[momdo]

I think that we need to retire HTML longdesc spec according to W3C Process Document to match the real world.

[momdo]

FYI: w3c/html-aam#23

[fstrr]

Note: the longdesc attribute is used as an example in Understanding Requirement 2 in WCAG 2.0's Understanding Conformance document, which is linked to from WCAG 2.1's Conformance section.

Sometimes, supplemental information may be available from another page for information on a page. The longdesc attribute in HTML is an example. With longdesc, a long description of a graphic might be on a separate page that the user can jump to from the page with the graphic. This makes it clear that such content is considered part of the Web page, so that requirement #2 is satisfied for the combined set of Web pages considered as a single Web page.