Re: The test for the correct use of longdesc should be conditional on its application

On Tue, Jan 4, 2011 at 5:18 AM, <noreply@w3.org> wrote:

>
> Name: Detlev Fischer
> Email: fischer@dias.de
> Affiliation: DIAS GmbH
> Document: TD
> Item Number: H45
> Part of Item: Applicability
> Comment Type: general comment
> Summary of Issue: The test for the correct use of  longdesc should be
> conditional on its application
> Comment (Including rationale for any proposed change):
> The test for the correct use of  longdesc should be conditional on its
> application in the first place. The first check
>
> 1. Check that the img element has a longdesc
> attribute.
>  is not meaningful for any img and redundant for those that actually carry
> the longdesc attribute.
>
> (The descripton may also mention the drawback that alternative text via
> longdesc is not usually accessible to sighted users and might therefore be
> supplied redundantly.)
>
>
>
> Proposed Change:
> So the test in my opinion should start with a conditional:
>
> "If longdesc is used on images to supply alternative text:"
>
> ...then test #2 and #3 (as #1 and #2)
>
>
>
> ================================
Response from the Working Group
================================
Techniques are all optional by nature. You do not have to use this
technique. If you are not using this technique to meet SC 1.1.1 for an
image, it doesn't matter that the image will fail the test procedure, that
is, that it will not have a longdesc attribute.

If you want to use something other than longdesc, then you wouldn't use this
technique and you wouldn't encounter the test.

We are clarifying this issue by adding a section "Testing techniques" in the
introduction to techniques: "Test procedures for techniques apply only to
verify proper application of that technique. They do not test the success
criteria. Tests of the success criteria require first determining which
techniques are applicable, and then following the test procedures for those
techniques."

Loretta Guarino Reid, WCAG WG Co-Chair
Gregg Vanderheiden, WCAG WG Co-Chair
Michael Cooper, WCAG WG Staff Contact


On behalf of the WCAG Working Group