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Issue 357: Proposed revision to applicability provision

From: Ian Jacobs <ij@w3.org>
Date: Fri, 05 Jan 2001 14:41:55 -0500
Message-ID: <3A562383.1364E6FA@w3.org>
To: w3c-wai-ua@w3.org

Section 3.3 of the 29 December draft [1] includes the
following applicability provision:

  "The checkpoint requires control of content properties 
  (e.g., video or animation rate) that the subject of the claim
  cannot control (e.g., the format does not allow it) 
  or does not recognize (e.g., because the property is controlled
  by a script in a manner that the subject of the claim 
  cannot recognize)."

Recall that this applicability provision is here to cover
cases such as the following:

 * Captions are "burned" into video.
 * Streamed content that may not be rewindable
 * Information embedded in scripts.

Al raised some concerns about this provision (issue 357), and
I got an action item at the AOL ftf meeting to proposal a
revision [2].

In discussions with Al, it became apparent that there might be
two ways to interpret "the subject cannot control" properties
of a format:
  1) The format forbids it (e.g., if you do this, you don't conform).
  2) The format doesn't enable it (e.g., due to limits in the format).

I therefore propose to modify the applicability provision 
to state more clearly that point (2) is intended:

  "The checkpoint requires control of a content property
   that the subject cannot recognize because of how the
   content has been encoded in a particular format. Some
   examples of this include: captioning information that
   is "burned" into a video presentation and cannot be
   recognized as captions per se, streamed content that
   cannot be fast advanced or reversed, information
   or relationships embedded in scripts in a manner that
   cannot be recognized.

This wording is consistent with the model that the user
agent is responsible for what is encoded in the format
(which may be less than what the author knows about
the content).

 - Ian

[1] http://www.w3.org/WAI/UA/WD-UAAG10-20001229/#applicable
[2] http://www.w3.org/WAI/UA/2000/11/minutes-20001116#issue-357
Ian Jacobs (jacobs@w3.org)   http://www.w3.org/People/Jacobs
Tel:                         +1 831 457-2842
Cell:                        +1 917 450-8783
Received on Friday, 5 January 2001 14:41:57 UTC

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