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Re: Moving longdesc forward

From: Benjamin Hawkes-Lewis <bhawkeslewis@googlemail.com>
Date: Wed, 4 May 2011 07:40:21 +0100
Message-ID: <BANLkTi=qWsF3MW3F6MmVGa3R6U62Ey7VtQ@mail.gmail.com>
To: Leif Halvard Silli <xn--mlform-iua@xn--mlform-iua.no>
Cc: Laura Carlson <laura.lee.carlson@gmail.com>, HTML Accessibility Task Force <public-html-a11y@w3.org>
On Wed, May 4, 2011 at 2:26 AM, Leif Halvard Silli
<xn--mlform-iua@xn--mlform-iua.no> wrote:
> I concur with Richard:
>
> ]] Change structured content to structured host language content.
>   We don't want to use PDF to describe HTML or vice versa [[
>
> Laura, perhaps you should take in this somewhere, if it isn't there?

Exactly what constraints are you guys proposing?

On the authoring side, if I have an HTML5 document and I link to an HTML
document claiming conformance with HTML4, is that conforming?  What if I link
to an XHTML5 document? What if I link to a compound document format that
includes the XHTML5 vocabulary?

Note that if we impose such a constraint we will render some existing longdesc
use non-conforming. Three of Laura's examples of @longdesc in the wild use plain
text for long descriptions.

http://www.d.umn.edu/~lcarlson/research/ld.html#fakoo

http://www.d.umn.edu/~lcarlson/research/ld.html#securian

http://www.d.umn.edu/~lcarlson/research/ld.html#buffalo

Since a single URL can serve multiple formats, on the user agent side, we'd
need to add a requirement that the URL be requested using an Accept header
giving a higher quality value to the desired media types.

> Nevertheless, some comments on things that goes directly on my
> own comments:
>
>    [ snip ]
>    When interleaved with other content, long text alternatives must be
>
> Comment: singular form is better: "[a particular] long text alternative"

Agreed.

>    identified as precisely as possible, for example by including a fragment
>    in the URL identifying the start of the long text alternative.
>
> Comment: I don't think we win very much by not making it a MUST. Those
> who don't understand the MUST will not restrict them from pointing to
> whatever they will, while the others will with a MUST will be
> encouraged to do it correctly.

The text I proposed makes it a "MUST".

>    For example, the following snippet defines an image of a chart with a short
>    text alternative and a long text alternative elsewhere in the same
>    document. The short text alternative is placed in the alt attribute, while
>    the long text alternative is precisely linked using a longdesc URL
>    including a fragment identifier:
>
>        <img src=october-sales-chart.png
>             alt="October sales chart"
>             longdesc=#chart-description>
>        <details>
>            <summary>Description</summary>
>            <p id=chart-description>Bar Chart showing sales for October.
>            There are 6 salespersons. Maria is highest with 349 units. Frances
>            is next with 301. Then comes Juan with 256, Sue with 250, Li with
>            200 and Max with 195. The primary use of the chart is to show
>            leaders, so the description is in sales order.</p>
>        </details>
>
> Comment: It is seems problematic to mix <details> into this.

Problematic how exactly? (Wondering if this suggests something
else that needs specifying.)

> Not sure we win anything by doing so.

Can you suggest an alternative concise example that illustrates same-page
@longdesc? :)

--
Benjamin Hawkes-Lewis
Received on Wednesday, 4 May 2011 06:44:37 GMT

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