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Re: Technique H45 procedure description incomplete

From: Loretta Guarino Reid <lorettaguarino@google.com>
Date: Mon, 1 Dec 2008 15:55:54 -0800
Message-ID: <824e742c0812011555g469bc5dbmfba87fc59d8410cf@mail.gmail.com>
To: Dylan Nicholson <d.nicholson@hisoftware.com>
Cc: "public-comments-wcag20@w3.org" <public-comments-wcag20@w3.org>
Hi, Dylan,

It feels like there is some confusion about the sufficient techniques. They
are consistently written to apply to a single instance of content covered by
the corresponding success criterion. It may turn out that the author always
uses the same technique, but we have been careful not to make that
assumption when describing the technique.

For instance, some images on an HTML page may need long descriptions and
some may not. So some images may be using G94: Providing short text
alternative for non-text content that serves the same purpose and presents
the same information as the non-text
content<http://www.w3.org/WAI/GL/WCAG20/WD-WCAG20-TECHS-20081105/G94>,
using H36: Using alt attributes on images used as submit
buttons<http://www.w3.org/WAI/GL/WCAG20/WD-WCAG20-TECHS-20081105/H36>
for the short text alternative. Other images on the same page may be using G95:
Providing short text alternatives that provide a brief description of the
non-text content<http://www.w3.org/WAI/GL/WCAG20/WD-WCAG20-TECHS-20081105/G95>,
using H36: Using alt attributes on images used as submit
buttons<http://www.w3.org/WAI/GL/WCAG20/WD-WCAG20-TECHS-20081105/H36>
for the short text alternative, and G92: Providing long description for
non-text content that serves the same purpose and presents the same
information <http://www.w3.org/WAI/GL/WCAG20/WD-WCAG20-TECHS-20081105/G92> ,
using H45: Using
longdesc<http://www.w3.org/WAI/GL/WCAG20/WD-WCAG20-TECHS-20081105/H45>for
the long description.

As  you noted, all the images are using H36, but they are using it in
different ways, and the test procedure for the value of the alt attribute
would be different in these two cases.

Success criterion 1.1.1 is a particularly complicated case, with a variety
of different situations described in the Sufficient Techniques section. And,
as we see, the ways of satisfying the success criterion may share
techniques.

On Mon, Dec 1, 2008 at 3:30 PM, Dylan Nicholson
<d.nicholson@hisoftware.com>wrote:

>  But that's tautologous - the technique IS the use of the LONGDESC
> element!
>

Correct. This technique describes the proper way to use LONGDESC for one
image to satisfy Success Criterion 1.1.1.

>
> The description of the procedure current strongly implies that every IMG
> requires a LONGDESC attribute, which is not correct.
>

The procedure describes the steps to apply to an image that is using this
technique, i.e., check that the img element has a longdesc attribute. The
procedure does not say to check that this is true for every image on the
page.

>
> This should to be contrasted with the ALT attribute, which *is *required
> for every IMG element, as per HTML/4.0 and XHTML/1.0 standards.  But oddly
> enough, the description of the procedure for technique H37 only says "Check
> that each img element which conveys meaning contains an altattribute", which is also incorrect - it should say
>
> "Check that every img element contains an alt attribute.  For img elements
> which convey mening, check that the attribute value is not blank".
>

As with H45, this is describing the check to be made for an image that is
using this technique. The technique does not imply that it must be used for
every image on the page. In the case of the alt attribute, validity would
lead the author to use it for every image, but that is a separate
consideration from the use the technique for a particular image.

This may be clearer when looking at techniques for other success criteria
where the techniques may use attributes that are not required for validity.
For instance, an author may mix a variety of techniques for abbreviations
when satisfying SC 3.1.4.

>
>
>  ------------------------------
>  *From:* Loretta Guarino Reid [lorettaguarino@google.com]
> *Sent:* Tuesday, 2 December 2008 10:16 AM
>
> *To:* Dylan Nicholson
> *Cc:* public-comments-wcag20@w3.org
> *Subject:* Re: Technique H45 procedure description incomplete
>
>  Any image *that uses this technique* must pass the check. However,
> different images, even on the same page, may use different techniques to
> meet the success criterion.
>
> On Mon, Dec 1, 2008 at 3:13 PM, Dylan Nicholson <
> d.nicholson@hisoftware.com> wrote:
>
>>  No, this is still problematic because it implies every IMG *should* have
>> a LONGDESC attribute.
>>
>> In reality, only a tiny percentage of real world IMG elements have
>> LONGDESC attributes.
>>
>> Having to check that the resource exists does make an automatic check
>> somewhat less efficient, but given that LONGDESC is so rare, it shouldn't be
>> an issue.
>>
>> At this point I doubt we would bother with implementing an automatic check
>> on the actual content of the page linked to.
>>
>>  ------------------------------
>> *From:* Loretta Guarino Reid [lorettaguarino@google.com]
>> *Sent:* Tuesday, 2 December 2008 9:55 AM
>> *To:* Dylan Nicholson
>> *Cc:* public-comments-wcag20@w3.org
>> *Subject:* Re: Technique H45 procedure description incomplete
>>
>>    On Wed, Nov 12, 2008 at 9:20 PM, Dylan Nicholson <
>> d.nicholson@hisoftware.com> wrote:
>>
>>>  H45 is described as
>>>
>>>  Procedure
>>>
>>>    1.
>>>
>>>    Check that a longdesc attribute exists.
>>>    2.
>>>
>>>    Check that the link in the longdesc attribute is valid
>>>    3.
>>>
>>>    Check that the long description describes the original non-text
>>>    content associated with it.
>>>
>>>  Expected Results
>>>
>>>    -
>>>
>>>    #1 through #3 are all true
>>>
>>> But a) it doesn't explain on what elements we are to check for the
>>> longdesc attribute - presumably it should be IMG elements only in this case,
>>> and not FRAMES and IFRAMEs
>>>
>>> b) surely it's not implying that to pass H45 every element that supports
>>> longdesc attributes must in fact do so??  That would cause virtually every
>>> page on the web to fail immediately, as I don't think I've ever seen a
>>> commercial site using LONGDESC - at least, not correctly.
>>>
>>> c) what is meant by valid?  That it's a valid url?  Or it actually points
>>> to a resource that really exists?  If the former, fine (and a very good
>>> idea, seeing I've seen quite a few cases where the LONGDESC attribute
>>> actually contains the descriptive text in the value, rather than a URL
>>> pointing to where to find the text), but if the latter, then testing this
>>> automatically becomes potentially expensive on a large site (well, it would,
>>> if anyone actually used LONGDESC).
>>>
>> ================================
>> Response from the Working Group
>> ================================
>>
>> Thank you, we have updated the test procedure to clarify these issues. See
>> http://www.w3.org/WAI/GL/WCAG20/WD-WCAG20-TECHS/H45.html .
>>
>> Could you let us know by Monday, December 8 whether you are satisfied with
>> our resolution? If that date is not possible, please reply to this message
>> indicating when you will be able to respond.
>>
>> If we do not hear from you by Monday, December 8, we will assume that you
>> are satisfied with the responses to your comments.
>>
>> Thanks again for the interest that you have taken in these guidelines.
>>
>> Loretta Guarino Reid, WCAG WG Co-Chair
>> Gregg Vanderheiden, WCAG WG Co-Chair
>> Michael Cooper, WCAG WG Staff Contact
>>
>>
>>
>
Received on Monday, 1 December 2008 23:56:34 UTC

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