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there are markup options [was: Re: img/alt summary attempt]

From: Al Gilman <Alfred.S.Gilman@IEEE.org>
Date: Tue, 15 Apr 2008 11:05:41 -0400
Message-Id: <3A582960-A630-4584-83ED-25E24197A44D@IEEE.org>
Cc: W3C WAI-XTECH <wai-xtech@w3.org>, public html for all <list@html4all.org>, HTML WG <public-html@w3.org>
To: Jim Jewett <jimjjewett@gmail.com>

Ref: http://www.w3.org/mid/ 
fb6fbf560804141048u16a79483ic355ef11366166dc@mail.gmail.com

Thank you Jim for bringing this together.

As a summary, it is a good summary.  I retitled this post
to emphasize that I am going into non-summary details.

Please accept this as complementing "what is agreed" and "what
is not agreed" with "feasible range for mutually acceptable solutions."

> -- Note -- HTML5 expands the use of LEGEND -- there may be cases where
> alt is not useful *because* it is redundant with LEGEND.  This case
> may not be covered in current WCAG Recommendations.

My understanding of the intent of the language in WCAG2 is that it does
accept a LEGEND as "the text alternative" IF the markup and the
specified semantics of the markup make it clear that the LEGEND is
specified to fill that role.  There are at least two ways to satisfy
this IF condition:

a) The HTML specification includes rules saying that when @alt is
missing and <legend> is present, that the content of the <legend> is
the text alternative for the image that goes with that <legend>.

b) There is relationship markup such as @aria-labelledby="theID- 
ofTheLEGEND" that
explicitly associates the two.

These two mechanisms are non-exclusive.  That is to say that both may
be available in the markup language profile.  Both could even be  
present on
an element as a transitional measure.

> (5d)  Several people have suggested specific magic values to indicate
> _decorative or _notsupplied.  This is more explicit, which should at
> least separate the reasons for missing alt.  Except that the people
> who care enough to do this may not be the ones writing problem pages,
> so it still might not work...

Likewise, there are various ways that this information could be  
incorporated
in the markup.  Reserved values of @alt is one option.  Defined values
of @role is another that could be considered.

The WCAG2 language "implemented in a way that it can be ignored by
assistive technology" should be read in this context to imply "is
indicated by the semantics of the markup applied to be suitable to  
ignore."

In terms of meeting WCAG function requirements, any defined markup
pattern can meet the requirements.

In terms of meeting the HTML5 performance goals of minimizing  
disruption,
disruption to the accessibility checking community has to be included
as relevant.  Here, leaving @alt as a required attribute and @alt="" as
the code for "suitable to ignore" has performance benefits in terms of
not disrupting incumbent practice.  But this has to be weighed against
the potential benefits of change, and the steps taken to mitigate the
negative effects of change.

Al

On 14 Apr 2008, at 1:48 PM, Jim Jewett wrote:
>
> Is there agreement on at least the following?
>
> (1)  Web pages SHOULD be accessible to all.
>
> (2)  Much of the improvement in alt over the past years is due to
> social pressure.
>
>     (2a)  HTML standards can be a force better accessibility.
>
>     (2b)  But standards are a very weak force -- requiring anything
> beyond interoperability will reduce their effectiveness.  [I know
> there isn't agreement on whether alt is worth the price -- I'm just
> confirming agreement that such a price exists.]
>
>     (2b)  This social pressure has included legal requirements -- it
> is easier to defend the time spent writing alt attributes if there is
> a law requiring accessibility and a standard stating that alt is
> required for accessibility.
>
>
> (3)  WCAG is the source of normative accessibility information from  
> the W3C.
>
>     (3a)  The HTML specification should at least reference WCAG2, and
> warn that a missing alt, even if adequate for HTML5, is not adequate
> for WCAG2.
>
>     (3b)  There is disagreement on whether conformance checkers should
> continue to flag missing alt attributes.
>
> (4)  alt SHOULD represent an equivalent to the picture, when possible.
>
> -- Note -- HTML5 expands the use of LEGEND -- there may be cases where
> alt is not useful *because* it is redundant with LEGEND.  This case
> may not be covered in current WCAG Recommendations.
>
> (5)  There is disagreement on what to do when alt cannot be a true  
> equivalent.
>
> (5a)  WCAG currently requires a description of intent, because that is
> better than nothing.
>
> (5b)  The current HTML5 drafts recommends leaving alt out completely,
> because machine-generated alt texts may be worse than nothing.
>
> (5c)  Common current practice is to either leave the alt out (and not
> worry about validity) or to set alt="" (and claim that the image is
> decorative).
>
> (5d)  Several people have suggested specific magic values to indicate
> _decorative or _notsupplied.  This is more explicit, which should at
> least separate the reasons for missing alt.  Except that the people
> who care enough to do this may not be the ones writing problem pages,
> so it still might not work...
>
> -jJ
>
Received on Tuesday, 15 April 2008 15:06:27 UTC

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