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Alt-Registry Proposal

From: Jan Richards <jan.richards@utoronto.ca>
Date: Mon, 03 May 1999 21:35:50 -0400
Message-ID: <372E4EF6.48CEEC92@utoronto.ca>
To: "w3c-wai-au@w3.org" <w3c-wai-au@w3.org>
From the document:

2.3.1: [Priority 1] 
     Prompt the author to provide alternative content (e.g., captions,
descriptive video). 
2.3.2: [Priority 1] 
     Prompt the author for all missing structural information (e.g., in
     FIELDSET, OPTGROUP and LEGEND for form controls). 
2.3.3: [Priority 2] 
     Provide pre-written alternative content for all multimedia files
packaged with the
     authoring tool. 
2.3.4: [Priority 3] 
     Provide a mechanism to manage alternative content for multimedia
objects, which
     retains and offers for editing pre-written or previously linked
alternative content. 
2.3.5: [Priority 1] 
     Do not insert automatically generated (e.g., the filename) or
place-holder (e.g., "image")
     equivalent text, except in cases where human-authored text has been
written for an
     object whose function is known with certainty. 

Jan's Alt-Text Registry Technique Proposal

In checkpoint 2.3.4 a recommendation is made that mentions the provision
of a "mechanism to manage alternative content". This checkpoint is
prioritized as a level 3, meaning that in itself, it does not have a
critical effect on an authoring tool's likelihood of producing
accessible mark-up. However, several limited  extensions to this
alternative content mechanism (ACM) have the potential to simultaneously
meet several higher priority checkpoints and dramatically improve the
usability of an access aware authoring tool . In particular:

1. The ACM should maintain a list of associations between object file
names and authored responses to prompts for alternative content (as per
checkpoint 2.3.1 [Priority 1]). The alternative content may take the
form of short strings (i.e. "alt"-text) or pointers to descriptive files
(i.e. "longdesc", transcripts, etc.). Multiple associations for the same
object for different languages or contexts should also be handled.
2. The ACM would offer the associated alternative content as a default
whenever the appropriate associated object is selected for insertion. If
no previous association is found the field should be left empty (i.e. no
purely rule-generated alternative content should be used). Note: the
term "default" implies that the alternative content is offered for the
author's approval. The term does not imply that the default alternative
content is automatically placed without the author's approval. Such
automatic placement may only occur when in situations where the function
of the object is known with certainty as per checkpoint 2.3.5 [Priority
1]. Such a situation might arise in the case of a "navigation bar
builder" that places a navigation bar at the bottom of every page on a
site. In this case, it would be appropriate to use the same "alt"-text
automatically for every instance of a particular image (with the same
target) on every page. 
3. The alternative content mechanism should be closely integrated with
the pre-written alternative content provided for all packaged multimedia
files, as per checkpoint 2.3.3 [Priority 2]. This would allow the
alternative content to be automatically retrieved whenever the author
selected one of the packaged objects for insertion. An important benefit
of the system would be the ease of adding a keyword search capability
that would allow efficient location of multimedia based on their
alternative content.

Jan Richards
University of Toronto
Received on Monday, 3 May 1999 21:37:31 UTC

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