Proposal checkpiont 2.7: Solution for repair text should not be minimal requirement

Hello,

In the 9 March draft of the UAAG 1.0 [1], checkpoint 2.7 
reads:

   2.7 Allow configuration to generate repair text when 
       the user agent recognizes that the author has failed
       to provide conditional content that was required by 
       the format specification. If the missing conditional 
       content is included by URI reference, base the repair 
       text on the URI reference and content type. 
       Otherwise, base the repair text on element type  
       information.

I don't think that the solution for generating repair
text should be a minimal requirement to satisfy the checkpoint,
but rather one way to satisfy the checkpoint. As Charles
argued recently [2] on another topic, I think that the
techniques listed in the checkpoint may be sufficient,
but not necessary approaches to satisfying the checkpoint.
I think that a user agent can do much better than URI reference 
and mime type, and should not be prevented from doing do
(e.g., the UA might fetch the title of the resource designated
by the URI).

Therefore I propose rewording the checkpoint as follows:

 <NEW 2.7>
   Allow configuration to generate repair text when 
   the user agent recognizes that the author has failed
   to provide conditional content that was required by 
   the format specification. The user agent may satisfy
   this checkpoint by basing the repair text on any of
   the following available sources of information: URI
   reference, content type, or element type.
      Note: Some markup languages (such as HTML 4 [HTML4] and 
      SMIL 1.0 [SMIL] require the author to provide conditional
      content for some elements (e.g., the "alt" attribute on 
      the IMG element). 
 </NEW 2.7>

For the Techniques:

    * Allow configuration so that instead of generating
      repair text from a URI reference, the user agent
      retrieves the resource at that URI and extracts
      meaningful text (e.g., a title) from the resource
      as the basis of repair text. [It would even be
      possible to build a database of useful repair text
      to be consulted whenever a resource included by
      URI lacked required conditional content.]

Comments:

 a) I also think that any of the three pieces (URI 
    reference, content type, element type) should suffice
    (hence or rather than and).

 b) In general, content type is provided by HTTP headers,
    not in markup, and I would rather not require the UA
    to do a HEAD or GET call to find out the content type
    of a Web resource.

 c) I realize that this may make it harder to verify that
    the user agent has satisfied the intention of the 
    checkpoint. I hesitate to say that the repair text
    should meet WCAG expectations, because this is generated
    text and there is no guarantee that it will be useful.
    I don't think it's worth saying "the repair text needs
    to be useful to the user," though clearly that's the 
    intention.

 d) I propose deleting the last sentence of the Note:

    "When the author does not provide this required content, 
     the user agent is required by this document to generate 
     repair text."

 - Ian

[1] http://www.w3.org/WAI/UA/WD-UAAG10-20010309/
[2] http://lists.w3.org/Archives/Public/w3c-wai-ua/2001JanMar/0345.html
-- 
Ian Jacobs (jacobs@w3.org)   http://www.w3.org/People/Jacobs
Tel:                         +1 831 457-2842
Cell:                        +1 917 450-8783

Received on Thursday, 15 March 2001 10:43:43 UTC