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Re: Disparity between WCAG 2.0 and HTML5 editors definition of text alternative

From: Steven Faulkner <faulkner.steve@gmail.com>
Date: Fri, 11 Apr 2008 22:44:08 +0100
Message-ID: <55687cf80804111444r84a6ef5g30592803171ab967@mail.gmail.com>
To: "Ian Hickson" <ian@hixie.ch>
Cc: public-html@w3.org, wai-xtech@w3.org

The HTML5 editor's definition of text alternative is also inconsistent
with WCAG 1.0.

checkpoint 1.1 Provide a text equivalent for every non-text element

definition of equivalent from [http://www.w3.org/TR/WCAG20/#glossary]

    Content is "equivalent" to other content when both fulfill
essentially the same function or purpose upon presentation to the
user. In the context of this document, the equivalent must fulfill
essentially the same function for the person with a disability (at
least insofar as is feasible, given the nature of the disability and
the state of technology), as the primary content does for the person
without any disability. For example, the text "The Full Moon" might
convey the same information as an image of a full moon when presented
to users. Note that equivalent information focuses on fulfilling the
same function. If the image is part of a link and understanding the
image is crucial to guessing the link target, an equivalent must also
give users an idea of the link target. Providing equivalent
information for inaccessible content is one of the primary ways
authors can make their documents accessible to people with
disabilities.
    As part of fulfilling the same function of content an equivalent
may involve a description of that content (i.e., what the content
looks like or sounds like). For example, in order for users to
understand the information conveyed by a complex chart, authors should
describe the visual information in the chart.
    Since text content can be presented to the user as synthesized
speech, braille, and visually-displayed text, these guidelines require
text equivalents for graphic and audio information.



On 11/04/2008, Steven Faulkner <faulkner.steve@gmail.com> wrote:
> Ian, you asked for examples the HTML5 draft contradicts WCAG1/2
>  here is one you just provided yourself:
>
>  steve faulkner wrote:
>  > The Rorschach inkblot test example is covered in WCAG 2.0 [1] by the
>  > following:
>  >
>  > "Sometimes content is primarily intended to create a specific sensory
>  > experience that words cannot fully capture. Examples include a symphony
>  > performance, works of visual art etc. For such content, text
>  > alternatives at least identify the non-text content with a descriptive
>  > label and where possible, some descriptive text. If the reason for
>  > including the content in the page is known and can be described it is
>  > helpful to include that information."
>  >
>  > [1] http://www.w3.org/TR/2007/WD-UNDERSTANDING-WCAG20-20071211/text-equiv-all.html
>
>  Ian hickson wrote:
>  "I disagree with this advice; I think it is harmful as it confuses titles
>  and captions with alternatives, and it removes the ability for an AT to
>  distinguish images that can be replaced by text with no indication of the
>  image's existence with images that are key to the content."
>
>  It would appear that there is a disparity between what WCAG 2.0
>  considers a text alternative and what you consider a text alternative
>
>  WCAG 2.0 definition:[http://www.w3.org/TR/WCAG20/#text-altdef]
>
>  "Text alternative
>  programmatically determined text that is used in place of non-text
>  content, or text that is used in addition to non-text content and
>  referred to from the programmatically determined text
>
>  Example: An image of a chart is described in text in the paragraph
>  after the chart. The short text-alternative for the chart indicates
>  that a description follows. "
>
>  Ian hickson's definition:
>  [http://lists.w3.org/Archives/Public/public-html/2008Apr/0285.html]
>
>  "The idea of alternative text is that you can substitute it for the image
>  without saying that there was an image, and the experience should be
>  equivalent."
>
>  I don't believe (but I may be wrong) that you are in a position to
>  enforce your own definition of what constitutes as a  "text
>  alternative" and use it to provide normative/informative statements
>  about alt use in the HTML5 specification.
>
>  I have previously brought this issue to the PF WG's attention [1] and
>  am awaiting their advice.
>
>  [1]http://lists.w3.org/Archives/Public/wai-xtech/2008Mar/0041.html
>
>  ---------- Forwarded message ----------
>  From: Ian Hickson <ian@hixie.ch>
>  Date: 11 Apr 2008 20:52
>  Subject: Re: several messages relating to the alt="" attribute
>  To: Steven Faulkner <faulkner.steve@gmail.com>
>  Cc: public-html@w3.org
>
>
>  On Fri, 11 Apr 2008, Steven Faulkner wrote:
>   >
>   > this is not acceptable:
>   >
>   >   <figure>
>   >    <img src="r14.jpeg">
>   >    <legend>Rorschach inkblot test #14</legend>
>   >   <figure>
>   >
>   > while this is:
>   >
>   >   <figure>
>   >    <img src="r14.jpeg" alt="An abstract, ambiguous shape">
>   >    <legend>Rorschach inkblot test #14</legend>
>   >   <figure>
>
>
>  I disagree. I think "An abstract, ambiguous shape" is a fine title, but
>   it's not alternative text.
>
>   The idea of alternative text is that you can substitute it for the image
>   without saying that there was an image, and the experience should be
>   equivalent. For example:
>
>    The <img src=cat.png alt=cat> sat on the <img src=mat.png alt=mat>.
>
>   ...could be read as "The cat sat on the mat." and it would be fine.
>
>   However, replacing an inkblot test with the text "an abstract, ambiguous
>   shape" defeats the entire point of the test. The user knows full well what
>   an inkblot test is, that's what the rest of the page says. The right thing
>   is for the AT to indicate the presence of the image and try to provide a
>   way for the user to investigate the image itself.
>
>   Why is it not acceptable to omit the alt text?
>
>
>
>   > The Rorschach inkblot test example is covered in WCAG 2.0 [1] by the
>   > following:
>   >
>   > "Sometimes content is primarily intended to create a specific sensory
>   > experience that words cannot fully capture. Examples include a symphony
>   > performance, works of visual art etc. For such content, text
>   > alternatives at least identify the non-text content with a descriptive
>   > label and where possible, some descriptive text. If the reason for
>   > including the content in the page is known and can be described it is
>   > helpful to include that information."
>   >
>
>  > [1] http://www.w3.org/TR/2007/WD-UNDERSTANDING-WCAG20-20071211/text-equiv-all.html
>
>
>  I disagree with this advice; I think it is harmful as it confuses titles
>   and captions with alternatives, and it removes the ability for an AT to
>   distinguish images that can be replaced by text with no indication of the
>   image's existence with images that are key to the content.
>
>
>   --
>
>  Ian Hickson               U+1047E                )\._.,--....,'``.    fL
>   http://ln.hixie.ch/       U+263A                /,   _.. \   _\  ;`._ ,.
>   Things that are impossible just take longer.   `._.-(,_..'--(,_..'`-.;.'
>
>
>  --
>  with regards
>
>  Steve Faulkner
>  Technical Director - TPG Europe
>  Director - Web Accessibility Tools Consortium
>
>  www.paciellogroup.com | www.wat-c.org
>  Web Accessibility Toolbar -
>  http://www.paciellogroup.com/resources/wat-ie-about.html
>


-- 
with regards

Steve Faulkner
Technical Director - TPG Europe
Director - Web Accessibility Tools Consortium

www.paciellogroup.com | www.wat-c.org
Web Accessibility Toolbar -
http://www.paciellogroup.com/resources/wat-ie-about.html
Received on Friday, 11 April 2008 21:44:44 GMT

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