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RE: Conformance Level Clarification

From: John M Slatin <john_slatin@austin.utexas.edu>
Date: Tue, 15 Feb 2005 09:50:32 -0600
Message-ID: <6EED8F7006A883459D4818686BCE3B3B7ADE01@MAIL01.austin.utexas.edu>
To: "Chris Ridpath" <chris.ridpath@utoronto.ca>, <jasonw@ariel.its.unimelb.edu.au>
Cc: "WAI WCAG List" <w3c-wai-gl@w3.org>

Chris wrote:
<blockquote>
Currently, each success criteria does *not* have 3 levels of
conformance. To conform to a success criteria the author must meet the
success criteria. There's no room for going below or above what's
defined in the SC - there's no levels at the technology specific layer.
I'm suggesting that we allow for 3 levels per success criteria.

</blockquote>
It's true that there are no *levels* for individual success criteria.
Rather, each *guideline* is supported by success criteria, and the
success criteria for each guideline are grouped under three possible
conformance levels.

At the top of the hierarchy in the Guidelines document there are four
Principles: Perceivable, Operable, Understandable, and Robust.

Under each of the Principles there are one or more Guidelines.

Under each Guideline there are three Levels.

At each Level there are 0 or more Success Criteria.

So a success criterion doesn't have levels.  The guidelines have levels,
and the success criteria live at those levels.

John


"Good design is accessible design." 
John Slatin, Ph.D.
Director, Accessibility Institute
University of Texas at Austin
FAC 248C
1 University Station G9600
Austin, TX 78712
ph 512-495-4288, f 512-495-4524
email jslatin@mail.utexas.edu
web http://www.utexas.edu/research/accessibility/


 



-----Original Message-----
From: Chris Ridpath [mailto:chris.ridpath@utoronto.ca] 
Sent: Tuesday, February 15, 2005 8:26 am
To: jasonw@ariel.its.unimelb.edu.au
Cc: John M Slatin; WAI WCAG List
Subject: Re: Conformance Level Clarification


>  > Level 1 alt text would only be required to meet the level 1
requirements
>  > while level 2 alt text would be required to meet both level 1 and 
> level
2
>  > requirements.
>
> The same as all other success criteria.
>
Currently, each success criteria does *not* have 3 levels of
conformance. To conform to a success criteria the author must meet the
success criteria. There's no room for going below or above what's
defined in the SC - there's no levels at the technology specific layer.
I'm suggesting that we allow for 3 levels per success criteria.

> It might be argued that in dealing with complicated images, a short 
> label should be provided in the ALT attribute and full detail in a 
> document referred to by LONGDESC, but that's an HTML-specific 
> constraint that can't be expressed in the WCAG success criteria, which

> have to apply across languages and formats.
>
I think there's consensus that a short description is provided by the
ALT attribute and the LONGDESC is used for a longer description. Yes,
this is HTML specific and should not be expressed in the general success
criteria. It goes in the technology specific layer.

> For example, how would you
> apply it to the SVG DESC element?
>
I'm not sure. The people that are working on the SVG technology layer
would have to make that determination.

> I would have thought that the definition of "text alternative" would 
> exclude place-holder values at level 1. A place-holder value doesn't 
> provide the same functionality or information as the non-text content.
>
Perhaps you're right. I could agree but I feel there is pressure to move
this sort of conformance test (placeholder text) up to level 2 so that's
why I suggested it there. This is why we need the 3 levels to work with.
Currently a conformance test is either in or out unless we resort to
other categories such as "optional" or "best practice". If we've got the
3 levels then we can keep the test but move it around to the appropriate
level and there's no need for defining other categories.

Cheers,
Chris
Received on Tuesday, 15 February 2005 15:50:33 GMT

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