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Formalizing WCAG 2.0 test procedures

From: Vicente Luque Centeno <vlc@it.uc3m.es>
Date: Wed, 6 Dec 2006 14:33:35 +0100 (CET)
To: Shadi Abou-Zahra <shadi@w3.org>
cc: public-wai-ert@w3.org
Message-ID: <Pine.LNX.4.61.0612061349540.17007@violin.it.uc3m.es>


Hi Shadi (nice to read from you :-),

> Please find information about the work of the WCAG 2.0 Test Samples 
> Development Task Force (TSD TF), and how this relates to the "Test Procedure" 
> sections of the WCAG 2.0 Techniques:
>
> TSD TF Home Page:
> * <http://www.w3.org/WAI/ER/2006/tests/>
>
> WCAG 2.0 Test Samples:
> * <http://www.w3.org/WAI/ER/tests/>

As far as I can see from 
http://www.w3.org/WAI/ER/2006/tests/tests-tf#objectives:

<blockquote 
cite="http://www.w3.org/WAI/ER/2006/tests/tests-tf#objectives"> "The 
objective of TSD TF is to develop test samples for WCAG 2.0 Techniques 
(content examples that demonstrate correct or incorrect implementation of 
WCAG 2.0 Techniques). TSD TF will not develop test procedures for WCAG 2.0 
Techniques or definitive interpretations thereof but will review the test 
procedures to be unambiguous and send feedback to WCAG WG."
</blockquote>

I think providing tests samples (of what is good and what is bad) is 
clearly OK, but I am farther concerned on the test procedures, the rules, 
ie, the conditions that actually say what is good and what is bad. I am 
still waiting for that from W3C. Maybe I got missed and it's being 
targeted somewhere else? Did I loose the proper link?

For instance, at 
http://www.w3.org/TR/2006/WD-WCAG20-TECHS-20060427/Overview.html#H37

it's said that images must have an "alt" attribute. "Description", 
"resources" and "examples" are provided, but the "Tests" section says just 
the word "Procedure" (only one simple word open to interpretation with no 
formalization). It would be better to say that the "alt" attribute is 
required on every image, and you can formalize that using 
XSLT/XQuery/Schematron/Clix/LRAE (I'd suggest XSLT or XQuery because all 
the other ones only add syntactic sugar). For instance, with XSLT:

<xsl:template match="//img[not(@alt)]">
     <xsl:message>Images with no alt attribute</xsl:message>
</xsl:template>

or (for generating reports in HTML):

<xsl:for-each select="//img[not(@alt)]">
   <li>Image with no alt attribute:
 	<xsl:apply-templates select="." mode="print" />
   </li>
</xsl:for-each>

By the way, XSLT could be used to generate EARL reports as well. ;-)

> Note that this group is currently still forming but we expect to publish 
> first results fairly soon. Let me know if you have questions or comments 
> regarding this work.

Maybe I didn't search well, ... is there any attempt to provide evaluation 
tests procedures (beyond sample tests)? Or is it still a "for-the-future" 
work? Maybe I didn't look at the appropriate pages? As you already know, I 
would really be happy to collaborate with that. :-)

P.S.: It's OK to have a big & complete test sample repository, with 
examples of what is good and what is bad, but I think it would have much 
more value if every/most/as many as possible/some of these test samples 
would come with a declarative rule/condition that formalizes such 
conditions is a machine testable way. It is OK. to say that:

<img src="companylogo.gif">			BAD PRACTICE
<img src="companylogo.gif" alt="Company Name">  GOOD PRACTICE

but it's better if comes with a rule saying that the following template 
will never instanciate.

<xsl:template match="//img[not(@alt)]">
     <xsl:message>Images with no alt attribute</xsl:message>
</xsl:template>

>
> Best,
>  Shadi
>
>
> -- 
> Shadi Abou-Zahra     Web Accessibility Specialist for Europe |
> Chair & Staff Contact for the Evaluation and Repair Tools WG |
> World Wide Web Consortium (W3C)           http://www.w3.org/ |
> Web Accessibility Initiative (WAI),   http://www.w3.org/WAI/ |
> WAI-TIES Project,                http://www.w3.org/WAI/TIES/ |
> Evaluation and Repair Tools WG,    http://www.w3.org/WAI/ER/ |
> 2004, Route des Lucioles - 06560,  Sophia-Antipolis - France |
> Voice: +33(0)4 92 38 50 64          Fax: +33(0)4 92 38 78 22 |
>
Received on Wednesday, 6 December 2006 13:33:55 GMT

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