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Alternatives for Applets and Objects; and the Longdesc

From: Leonard R. Kasday <kasday@acm.org>
Date: Wed, 16 Feb 2000 14:45:26 -0500
Message-Id: <4.2.2.20000216141935.00a6af00@pop3.concentric.net>
To: "wai-wcag-editor@w3.org" <wai-wcag-editor@w3.org>
Cc: w3c-wai-er-ig@w3.org
WCAG checkpoint 1.1 says

cf. http://www.w3.org/TR/1999/WAI-WEBCONTENT-19990505/#gl-provide-equivalents

quote

[bullet] Use "alt" for the IMG, INPUT, and APPLET elements, or provide a 
text equivalent
    in the content of the OBJECT and APPLET elements.

[bullet] For complex content (e.g., a chart) where the "alt" text does not 
provide a complete
    text equivalent, provide an additional description using, for example, 
"longdesc" with
    IMG or FRAME, a link inside an OBJECT element, or a description link.

end quote

This only suggests two possibilities: ordinary text or a link to text.  I 
think it would be better to suggest "functionally equivalent accessible HTML"

For example, suppose there's an applet with scrolling headlines.  A sighted 
user clicks a headline when it appears to get the corresponding 
story.   Checkpoint 1.1 offers two suggestions: either

1. Put text there, like "Scrolling headlines"
2. provide a link to additional textual description.

It would be better to have as alternate content a list of of all the 
headlines, each one being a link to the corresponding story.  This is 
functionally equivalent.

A similar argument applies to LONGDESC.  The guidelines and techniques seem 
to imply that longdesc simply points to a text file.  For example, 
technique 4.7.1 in http://www.w3.org/TR/WAI-WEBCONTENT-TECHS/#images

has the following example

quote


>           Example.
>
>                  <IMG src="97sales.gif" alt="Sales for 1997"
>                       longdesc="sales97.html">
>
>           In sales97.html:
>
>                A chart showing how sales in 1997 progressed. The chart
>                is a bar-chart showing percentage increases in sales
>                by month. Sales in January were up 10% from December 1996,
>                sales in February dropped 3%, ..

end quote

Since longdesc is a link, it can point to richer content; namely 
functionally equivalent accessible HTML.  For example, for the above sales 
chart, there could be a data table in addition to the textual description.

Similarly, if the image was an organization tree, the longdesc could point 
to a page that used headings to show the tree structure, e.g. using H1, H2, 
... or nested lists.

Of course I'm not saying that you always need this complex an alternative, 
but it should be suggested as a richer alternative.

Len
-------
Leonard R. Kasday, Ph.D.
Institute on Disabilities/UAP, and
Department of Electrical Engineering
Temple University
423 Ritter Annex, Philadelphia, PA 19122

kasday@acm.org
http://astro.temple.edu/~kasday

(215) 204-2247 (voice)
(800) 750-7428 (TTY)
Received on Wednesday, 16 February 2000 14:43:16 GMT

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