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Re: Marking up alternative versions of content

From: Jason White <jason@jasonjgw.net>
Date: Sat, 4 Aug 2007 14:44:25 +1000
To: public-html@w3.org
Message-ID: <20070804044425.GA7566@jdc.local>

On Fri, Aug 03, 2007 at 10:06:25PM -0500, Robert Burns wrote:

> Does this mean your proposal specifies a content model of "block-level or 
> inline, but not both" (I'm still trying to understand what transparent 
> means so perhaps that's the exact same thing).

http://www.w3.org/html/wg/html5/#transparent (sec. 3.3.3.3)

I agree with all of Rob's remaining points, including his separate post
suggesting a flattening of the <object> hierarchy of fallbacks by allowing
<alt> to be used instead, with appropriate @for references.

Since the proposed content model of <alt> is transparent, the following
alternative to @longdesc is possible:

<p><img src="compleximage.jpg" alt="label" id="compleximage">
<alt for="compleximage"> <a href="description.html" title="Detailed description
of image">Description</a></alt>

This has the further advantage that the UA behaviour associated with a link,
unlike @longdesc, is well defined. The author also has the flexibility to
insert the description inline:
<p> <img src="compleximage.jpg" alt="label" id="compleximage"> [...] </p>
<alt for="compleximage"> <p> [multiple paragraphs of long description] </alt>

An assistive technology, voice browser, etc., could give the user the option
of reading the description immediately after the image, or after the remainder
of the containing block-level element (a paragraph in this case) has been
read, or at the end of the document etc. The user agent/assistive technology
could also allow the description to be transformed into a link, as in the
preceding example - in fact, an XSLT style sheet could do this on the client
or server side, according to the user's preferences, and I'm sure this could
easily be scripted.

Having listened to numerous audio books with footnotes and figure descriptions
included, it is clear that the inability to adjust the order in which these
components are read, or to suppress them entirely during the reading,
constitutes a substantial limitation that reduces one's comprehension of the
material. This is another reason why "side-by-side" delivery of alternatives,
associated only implicitly with the corresponding media objects, is
insufficient, and why it must be possible for the author to signal, in the
markup, what is an alternative for which element.
Received on Saturday, 4 August 2007 04:44:34 GMT

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