W3C home > Mailing lists > Public > w3c-wai-gl@w3.org > April to June 2005

RE: RE: working definition of baseline

From: Gregg Vanderheiden <gv@trace.wisc.edu>
Date: Sun, 8 May 2005 23:25:25 -0500
To: "'Jason White'" <jasonw@ariel.its.unimelb.edu.au>, "'Web Content Guidelines'" <w3c-wai-gl@w3.org>
Message-Id: <20050509042525.A67F31CC37A@m14.spamarrest.com>

Jason wrote (below)
If my baseline is required to be the minimal set of technologies needed 
for the content to be rendered at all, then I have failed the success 
criterion because the metadata format isn't included in the baseline as 
it degrades gracefully with respect to user agents that don't support it 
- they just won't get the text alternatives.
<end Jason>


Thanks Jason - but I'm having trouble. 
 
The only use of baseline I understood us to be using in conjunction with
WCAG conformance was one where the content would meet all guidelines (at the
level(s) claimed) if the baseline technology was there (present and turned
on).  

So how could it fail?  Or were you using baseline another way?   


 
Gregg

 -- ------------------------------ 
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 Jason White
Sent: Sunday, May 08, 2005 10:20 PM
To: Web Content Guidelines
Subject: Re: RE: working definition of baseline
Importance: High


On Sun, May 08, 2005 at 08:49:44PM -0500, John M Slatin wrote:
> 
> I have a feeling that this goes back to something that Wendy (I think) 
> said in an earlier thread about baseline and 4.2-- I'm remembering a 
> distinction drawn between technologies *required* by the content and 
> technologies *used* by the content.
> 
> The idea was that in the absence of a *required* technology content 
> would not be perceivable, operable, understandable, and robust, and 
> would not degrade gracefully-- it would simply break. The content
> *would* degrade gracefully in the absence of technology that was 
> merely "used."

This is the right distinction to be making here.

If the baseline is defined as those technologies which are *required* in
order for the content to be perceived/operated *at all* by any user agent,
then that's very different from defining it as those technologies which the
author thinks desirable to assume in evaluating conformance.

John asked for an example. Suppose there is a metadata format (Lisa has
defined one) in which text alternatives can be associated with non-text
content. Assume for the sake of argument that there are some
UAAG-conformant, or largely UAAG-conformant user agents which support this
format, and I publish a Web site in which all the text alternatives (along
with other information required by WCAG) are provided in this metadata
format.

Now I publish my baseline. My content will function in a user agent that
doesn't support the metadata format, but it will only satisfy guideline
1.1 under the assumption of a user agent that does, due to the technique I
have chosen to implement the success criterion.

If my baseline is required to be the minimal set of technologies needed for
the content to be rendered at all, then I have failed the success criterion
because the metadata format isn't included in the baseline as it degrades
gracefully with respect to user agents that don't support it
- they just won't get the text alternatives. If I can define my baseline
more broadly then I can pass guideline 1.1.

Suppose we opt for the first approach - my baseline is defined in terms of
the absolutely essential technologies needed for the content to be rendered,
which doesn't include my metadata format. Now, I can handle this by using
"browser sniffing" techniques (HTTP user agent headers or
CC/PP) to deny access to my content to user agents that don't support the
metadata format. I've just made it into a "required" technology for my
content by shutting out user agents that don't support it. Having done this,
it appears that I can now claim guideline 1.1 conformance, which presumably
is not the result we want.

Thoughts?
Received on Monday, 9 May 2005 04:25:34 UTC

This archive was generated by hypermail 2.3.1 : Wednesday, 5 February 2014 23:39:37 UTC