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RE: baseline_overview_draft.htm

From: Gregg Vanderheiden <gv@trace.wisc.edu>
Date: Sun, 20 Nov 2005 15:35:13 -0600
To: "'Gez Lemon'" <gez.lemon@gmail.com>
Cc: <w3c-wai-gl@w3.org>
Message-ID: <005f01c5ee1a$4ebdd030$ee8cfea9@NC6000BAK>

Hi Gez,

Let me see if I can answer your questions and capture the ideas that led to
this baseline approach.  

The baseline is what is required in a Conformance statement.
The "relied on" is optional

You have the correct understanding of baseline and of 'relied on'. 

So why have 'relied upon'  AND a baseline? 

Since the baseline MAY be required or dictated from above (e.g. company
policy or other policy) it may be useful for the author to state what they
actually relied upon. 

Also - you may have a baseline for an entire site -- but may want to specify
what is "relied upon" for a page or section of the site where that is much
less than the baseline for the whole site.  

In either case the author may, optionally,  make a 'relied upon' statement
which is a subset of the technologies in the baseline. 

Even when not mandated, having common baseline groups of technologies that
are generally supported is useful to both authors and user agent
manufacturers since they can design toward that (those) baselines.  Users
can also assemble or buy user agent environments that can handle these
common baseline sets of technologies. 



 -- ------------------------------ 
Gregg C Vanderheiden Ph.D. 
Professor - Ind. Engr. & BioMed Engr.
Director - Trace R & D Center 
University of Wisconsin-Madison 

-----Original Message-----
From: w3c-wai-gl-request@w3.org [mailto:w3c-wai-gl-request@w3.org] On Behalf
Of Gez Lemon
Sent: Sunday, November 20, 2005 2:39 PM
To: Gregg Vanderheiden
Cc: w3c-wai-gl@w3.org
Subject: Re: baseline_overview_draft.htm

I'm confused about the words "relied upon" and "used, but not relied upon"
in the document that defines the baseline. I thought the baseline was for
the author (or higher authority) to state the minimum set of technologies
that should be supported by the a user agent in order to make a conformance
claim. Particularly as the document states that other technologies may be
used providing they do not impact the accessibility of the content. This
seems to be a contradiction in terms, but will be important to understand in
terms of evaluating the accessibility of a website.

If a conformance claim states that CSS is used in the baseline, but doesn't
mention that it is relied upon, then it's reasonable to assume that the
content will adhere to WCAG 2.0 when style sheets are not supported or
disabled in the user agent. In which case, why mention CSS in the baseline?
The definition of baseline states that the technologies listed are the
minimum required to receive the content by a user agent, but other
technologies may be used providing they do not affect the accessibility of
the content. The same applies to other technologies, such as scripting. If
scripting is used without having an impact on the accessibility of the
document, why mention it in the baseline?

It might make sense to mention something that is absolutely necessary for
the baseline, like HTML, and then just use CSS, scripting, and other
technologies in a way that does not affect the accessibility of the
document. If these other technologies do not affect the accessibility, I
don't understand the rationale of declaring them in the baseline, as they
are not the minimum set of technologies required to meet the conformance
claim. It only makes sense to me to mention those items that are assumed to
be supported in order to make the conformance claim.

Best regards,


Supplement your vitamins
Received on Sunday, 20 November 2005 21:35:36 UTC

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