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Proposed modification to definition of "applicable checkpoint"

From: Ian Jacobs <ij@w3.org>
Date: Wed, 22 Sep 1999 12:02:38 -0400
Message-ID: <37E8FD9E.12776BE6@w3.org>
To: w3c-wai-ua@w3.org
Hello, 

In the 27 August draft [1], applicable checkpoint is defined
as follows:

<BLOCKQUOTE>
A checkpoint applies to a user agent unless: 
              a   
     * The checkpoint definition states explicitly that 
       it only applies to a different class of user agent. 

     * The checkpoint addresses a content type (script, 
       image, video, sound, applets, etc.)
       that the user agent does not recognize. 

     * The checkpoint refers to a content type that the user 
       agent recognizes but does not support natively. 

     * The checkpoint refers to the properties of an
       embedded object (e.g., video or animation rate) 
       that may not be controlled or accessed by the user agent. 
</BLOCKQUOTE>

I would like to change this definition as follows:

  The spirit of these guidelines is the following:
  If a user agent offers a functionality, it must 
  ensure that all users have access to that 
  functionality or an equivalent alternative. Thus,
  if the user agent supports keyboard input, it must 
  support accessible keyboard input. If the user
  agent supports images, it must ensure access to each image
  or an alternative equivalent supplied by the author.
  If a user agent supports style sheets, it must 
  implement the accessibility features of the style
  sheet language. If the user agent supports
  frames, it must ensure access to frame 
  alternatives supplied by the author.

  Not all user agents support every content
  type, markup language feature, input or output
  device interface, etc. When a content type, feature, or
  device interface is not supported, checkpoints with requirements
  related to it do not apply to the user agent. Thus,
  if a user agent supports style sheets at all,
  all checkpoints related to style sheet accessibility apply. 
  If a user agent does not support style sheets at all,
  the checkpoints do not apply.
 
  The applicability of checkpoints related to 
  markup language features is measured
  similarly. If a user agent supports tables, it must
  support the accessibility features of the language
  related to tables (or images, or frames, or video, or
  links, etc.). The Techniques Document includes information
  about the accessibility features of W3C languages such as HTML,
  CSS, and SMIL.

  The following summarizes criteria for applicability.
  A checkpoint applies to a user agent unless:

     * The checkpoint definition states explicitly that 
       it only applies to a different class of user agent. 

     * The checkpoint includes requirements about 
       a content type (script, image, video, sound, 
       applets, etc.) that the user agent does not 
       recognize at all.

     * The checkpoint includes requirements about 
       a content type that the user 
       agent recognizes but does not support natively.

     * The checkpoint refers to the properties of an
       embedded object (e.g., video or animation rate) 
       that may not be controlled or accessed by the user agent. 

     * The checkpoint includes requirements about an
       unsupported markup language or other technology
      (e.g., style sheets,  mathematical markup language, 
      synchronized multimedia, metadata description language, etc.)
   
     * The checkpoint refers to an unsupported
       input or output device interface. Note that if the 
       interface is supported at all, it must be 
       supported accessibly.

 - Ian


[1] http://www.w3.org/WAI/UA/WAI-USERAGENT-19990827 
-- 
Ian Jacobs (jacobs@w3.org)   http://www.w3.org/People/Jacobs
Tel/Fax:                     +1 212 684-1814
Cell:                        +1 917 450-8783
Received on Wednesday, 22 September 1999 12:03:03 GMT

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