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properties for evaluation of alternative representations

From: Leonard R. Kasday <kasday@acm.org>
Date: Wed, 14 Feb 2001 11:32:09 -0500
Message-Id: <>
To: w3c-wai-er-ig@w3.org
Per my action item from the last call, here's some proposed properties to 
evaluate various means of representing information in an alternative form 
(e.g. ALT attribute , target of a LONGDESC, SUMMARY attribute,  contents of 
an object, etc).

The possible values of these properties are informally described in 

Also, I've put hyphens in some of these, e.g. "should-exist".  These would 
not appear in actual EARL code.  The hyphens are just to help screenreaders 
read them more intelligibly.

exists (boolean)
Note: a null value, e.g. ALT="", counts as existing.  However, a 
null     value may not count as having high quality

should-Exist (bidirectional scale)
Sometimes a human judgment is needed to decide if a value should exist, 
e.g. for a LONGDESC.  It's a bidirectional Scale because, occasionally, 
existance can be harmful.  E.g. TITLE surpresses reading of ALT text in 
some browsers.

quality (Unidirectional Scale)
The quality of the item being judgment.  E.g. is the ALT text well phrased.

suggested-Replacement (text, html, or xhtml)
the human Evaluator's suggestion for replacing the item under consideration.

comment (text)
Free form entry of information.  Not interpretable by machine

An equally important issue is how we define the objects to which these 
properties apply.

For example, if we have an image tag with an ALT attribute, these 
properties could potentially  be connected to:

1. an RDF node corresponding to the image tag
2. an Xpointer pointing to the image tag
3. an Xpointer pointing to the ALT attribute (doesn't work if there isn't 
any ALT attribute)
4. An RDF node of type "evaluation statement" that is connected to the 
image tag by an "appliesTo" predicate.

  Personally, I'd favor (4).   I'll be talking about that in other email...

Leonard R. Kasday, Ph.D.
Institute on Disabilities/UAP and Dept. of Electrical Engineering at Temple 
(215) 204-2247 (voice)                 (800) 750-7428 (TTY)
http://astro.temple.edu/~kasday         mailto:kasday@acm.org

Chair, W3C Web Accessibility Initiative Evaluation and Repair Tools Group

The WAVE web page accessibility evaluation assistant: 
Received on Wednesday, 14 February 2001 11:32:44 UTC

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