[techs] d-link Test 9

In our recent straw poll, the group accepted the test for d-link:

test 9 - All IMG elements that have a LONGDESC attribute also have an
associated 'd-link'.
http://www.w3.org/WAI/GL/WCAG20/tests/test9.html

However there were several people that voted for killing it and most people
voted that it be "optional". I thought we should have some discussion on the
list as a result of the close decision.

The "d-link" was a temporary measure to support image long descriptions
until there was user agent support for the LONGDESC attribute. We know that
d-link will eventually be not required so the question is - when?

Is there yet enough user agent support for LONGDESC that we should not
require d-link? How do we judge when there is enough support for LONGDESC
that we can dump d-link. Is there something we can do to increase the
support of LONGDESC so d-link can be quickly removed?

Note that d-link is currently a level 1 requirement because it maps to
guideline 1.1, Level 1, Success Criteria 2. I believe that it should be a
level 2 or level 3 requirement.

Comments appreciated.

Cheers,
Chris