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Re: longdesc spec text

From: Laura Carlson <laura.lee.carlson@gmail.com>
Date: Wed, 27 Apr 2011 12:21:23 -0500
Message-ID: <BANLkTik5fFs1WgW+CPBxvnzo7XccEJTFMQ@mail.gmail.com>
To: Benjamin Hawkes-Lewis <bhawkeslewis@googlemail.com>
Cc: W3C WAI-XTECH <wai-xtech@w3.org>, HTMLwg <public-html@w3.org>, Leif Halvard Silli <xn--mlform-iua@xn--mlform-iua.no>
Hi Benjamin and everyone,

I put your version of the spec into the spec text template [1], adding
one additional paragraph derived from HTML 4. It is:

"Since an img element may be within the content of an a element, the
user agent's mechanism in the user interface for accessing the
"longdesc" resource of the former must be different than the mechanism
for accessing the href resource of the latter."

This would make the logo and lightbox use cases possible. That do you
think? Ideas to improve that paragraph?

I linked to this latest spec text sample from the change proposal's
details section [2]. It is identified with your initials BHL.

I'm also wondering if we should add the conformance checkers and
authoring tool paragraph from my first attempt at writing the spec
text [3]. It is:

"Conformance checkers and authoring tools should inspect the URL and
issue a warning if they suspect that the description resource is
unlikely to contain a description of the image (i.e., if the URL is an
empty string, or if it points to the same URL as the src attribute
unless the document contains an id that matches a longdesc#anchor, or
if it is indicative of something other than a URL.)"

What do you and everyone else think?

We still would need to figure out the additions for the rendering
section. Thoughts on the best way to do this? Do you or anyone have
ideas for spec text for that section?

Steve has some screenshots [4]. Leif has been collecting some too.
They might be good additions to the rendering section.

Thanks again.

Best Regards,

[1] http://www.d.umn.edu/~lcarlson/research/ld-spec-text2.html#ld
[2] http://www.w3.org/html/wg/wiki/ChangeProposals/InstateLongdesc#Details
[3] http://www.d.umn.edu/~lcarlson/research/ld-spec-text.html#ld
[4] http://www.html5accessibility.com/tests/img-longdesc.html

On 4/26/11, Benjamin Hawkes-Lewis <bhawkeslewis@googlemail.com> wrote:
> On Tue, Apr 26, 2011 at 6:31 PM, Laura Carlson
> <laura.lee.carlson@gmail.com> wrote:
>> Hi Ben,
>>> The spec language likely needs to be carefully coordinated with:
>>> http://dev.w3.org/html5/spec/links.html#following-hyperlinks
>> What text would you suggest for for longdesc in the  4.8.1 the img
>> element section? I'm open to suggestions.
> Hmm. I'd base it on the treatment of @cite here:
> http://dev.w3.org/html5/spec/grouping-content.html#the-blockquote-element
> So something like:
>   The requirements on the alt attribute's value are described in the
> next section.
>   Some images benefit from a long text alternative that is either too
>   long to be included in the main flow of the document or requires
>   structured markup that cannot be included in an @alt attribute. Such a
>   long text alternative of the image, if it has one, may be referenced in
>   the longdesc attribute.
>   If the longdesc attribute is present, it must be a /valid URL
>   potentially surrounded by spaces/
> (http://dev.w3.org/html5/spec/urls.html#valid-url-potentially-surrounded-by-spaces).
>   To obtain the corresponding long text alternative link, the value of
>   the attribute must be resolved relative to the element. The link must
>   point to either a different document from the image or a /fragment/
> (http://dev.w3.org/html5/spec/history.html#the-indicated-part-of-the-document)
>   of the same document that does not contain the image. User agents
>   should allow users to access long text alternatives.
>   The longdesc IDL attribute must reflect the element's longdesc content
>   attribute.
> I've preferred Understanding WCAG 2.0's language of "long text alternative"
> to "long description". I've also done my best with the problematic
> question of how long is too long.
> Personally, I'd be wary of saying "User agents should allow users to
> access long text alternative" here, but Hixie's draft includes "User agents
> should allow users to follow citation links" so I've included it for
> consistency. I've tried to phrase so it does not especially encourage
> opening a new browser context over inlining content.
> The @alt requirements section would probably need a new subsection
> describing what the @alt should be when the image also has a
> separate long description.
> --
> Benjamin Hawkes-Lewis

Laura L. Carlson
Received on Wednesday, 27 April 2011 17:21:52 UTC

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