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Re: Evaluating success criteria to false

From: Chaals Nevile <chaals@yandex.ru>
Date: Wed, 06 Jun 2018 01:26:35 +0200
To: w3c-wai-ig@w3.org
Message-ID: <op.zj5sqljmnd6f5a@ordhord>
On Wed, 06 Jun 2018 00:18:10 +0200, Mark Weiler <mweiler@alumni.sfu.ca>  
wrote:

>> According to WCAG 2.X, "satisfies a success criterion" means "the  
>> success criterion does not evaluate to 'false' >when applied to the  
>> page"
>
> Beyond using a WCAG Working Group published common failure, what is  
> necessary and sufficient for a success >criterion to evaluate to false?

Basically, a sound argument that the content failed to achieve the stated  
requirements.

The failure techniques are merely cases that are common enough that they  
were recognised by the guidelines working group and the argument was  
agreed to be sound enough and repeatable enough that they wrote it down so  
you don't have to do as much work.

For example, looking at 1.1.1, if you find an "ascii art" flowchart, that  
is not otherwise described in text, and is important to understanding the  
content, you could argue that the content fails to provide a text  
alternative of that "non text" content, on the basis that ASCII art isn't  
actually readable text.

As it happens, this is of course F72, but there is no formal requirement  
that you reference that in claiming that content failed to meet the  
success criterion. Do of course note that exceptions are part of the  
criterion, so if the ASCII art was purely decorative, your argument would  
be considered weak by your peers...

And that's the crux of this. The spec is written with the goal that an  
intelligent person testing some content can work out which ciretira are  
applicable, and whether they are met. The further material is meant to  
make that easier, in part through showing examples, and how a number of  
independent experts apply the principle in each example case.

The WAI ACT work is trying to codify some examples more formally, but I  
believe the assumption above that someone should be able to work it out  
without examples still holds for the general case.

If you find a case that is not covered, but you think it is an example  
likely to be repeated and so useful to others, I strongly encourage you to  
describe it to the guidelines Working Group, and ask them to consider it  
as a contribution to the techniques.

cheers

Chaals

-- 
Chaals: Charles (McCathie) Nevile find more at https://yandex.com
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Received on Tuesday, 5 June 2018 23:27:10 UTC

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