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WCAG and user agent support

From: Jason White <jasonw@ariel.its.unimelb.edu.au>
Date: Mon, 14 Mar 2005 20:41:59 +1100
Message-ID: <16949.23655.473426.283516@jdc.local>
To: Web Content Guidelines <w3c-wai-gl@w3.org>

Some time ago I wrote the following proposal which was never sent to
the list. Here it is, in slightly edited form. I am not advocating
this proposal but rather contributing it to the ongoing idscussion.

Option 1: require that every WCAG 2.0 conformance claim be linked to a
 profile specifying the formats/languages assumed to be implemented by
 UAAG-conformant user agents accessing the content. The profile would
 also include a UAAG conformance level and other information needed
 according to the UAAG conformance section.

Option 2: Same as option 1, except that the WCAG conformance claim
need not be linked to a UAAG profile, and a default profile is assumed
if the conformance claim does not refer to one. This default profile
would be specified in the guidelines and would amount to a default
user agent baseline which the person claiming conformance can override by linking
to an alternative UAAG conformance profile.

Option 3 (compatible with options 1 and 2): require that if no user
agents exist which conform to UAAG 1.0 according to the relevant UAAG conformance
profile, the WCAG-conformant content implements repair strategies that
duplicate or render unnecessary the functionality which at least one
user agent lacks, and which, if implemented by that user agent, would
bring it into conformance with UAAG 1.0 according to the specified

Note that the WCAG 2.0 techniques would have to be "parameterized"
according to the UAAG conformance that the content developer decides
to presuppose, in particular the technologies which are assumed to
have been implemented in a UAAG-conformant fashion. Thus, techniques
would need to be provided covering both the case in which a technology
is assumed, and that in which it is not.

Obviously, the "repair strategies" proposal exists to remove
shortfalls, and the "default UAAG conformance profile idea is there
for the convenience of authors and to allow WCAG to specify a default
user agent baseline without preventing content developers from
overriding it.

Advisory documentation could then be provided regarding choice and
construction of profiles.
Received on Monday, 14 March 2005 09:42:10 UTC

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