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Re: Proposal for level of control of Guideline 3 checkpoints (turn on/off)

From: Charles McCathieNevile <charles@w3.org>
Date: Sun, 9 Jul 2000 11:53:23 -0400 (EDT)
To: Ian Jacobs <ij@w3.org>
cc: w3c-wai-ua@w3.org
Message-ID: <Pine.LNX.4.20.0007091151130.27948-100000@tux.w3.org>
I agree with this (with some reservations in the case of scripts, but I
suspect you are right) except to point out that in the case of animations, we
are really dealing with something more than just blinking, and there is a
requirement where possible to be able to step through the animation (see the
checkpoints on control of video).

This is another case where we have a few bites at the goal of complete
accessibility - text equivalents may not be, and full accessibility for some
people will be best served by having the ability to see what is going on,
without it doing the flash-trigger thing.

Cheers

Charles McCN

On Sat, 8 Jul 2000, Ian Jacobs wrote:

  Hello,
  
  There are 8 checkpoints in Guideline 3 of the 7 July 
  UA Guidelines [1]. These are the "turn on/off" checkpoints
  that we started to discuss at the 29 June teleconference [2].
  We did not finish our discussion of what "turn on/off" meant,
  but we resolved that it meant "at least" configuration to
  not render its subject on loading of content. It may mean
  more than that for some checkpoints, but at least for the
  7 July Guideline, the phrase "turn on/off" has been deleted 
  in favor of more precise wording.
  
  Actually, of the 8 checkpoints of Guideline 3, 3.6 and 3.7
  concern changing content and have been studied previously.
  This leaves six checkpoints where we should ask the following
  questions:
  
  1) Beyond the ability to configure the UA not to render X,
     do we need to require the ability to configure the
     UA (globally) to render X at some point after loading? Would that
     be a P1 requirement? For example, checkpoint 3.3 reads:
  
       Allow the user to configure the user agent to render 
       animated or blinking text as motionless text.
  
     Do we need to be able to toggle a switch so that text can
     again be animated and blinking? I don't think that this would
     be a P1 requirement given that motionless text enables
     access to text content.
  
  2) Beyond the ability to configure the UA globally to render X,
     do we need the ability to control the UA so that individual
     pieces of content can be rendered/not rendered?
  
  Here are the checkpoints and some proposals for not
  adding additional levels of control, except for checkpoint 3.8.
  
  3.1 Allow the user to configure the user agent to not render
      background images. 
  
      Proposed: A global configuration to not render background
      images on loading suffices. If a background image conveys 
      important information, WCAG 1.0 requires a text equivalent.
      If users cannot read text on the background, they can
      configure the UA to not render the background image
      and reload.
  
      Note: This does not address the issue of multi-layered
      presentations and being able to turn off all layers other
      than the topmost layer. I propose that we not add such
      a requirement for this version of the Guidelines.
  
  3.2 Allow the user to configure the user agent to not 
      render video.
  
      Proposed: A global configuration to not render video
      on loading suffices since additional control of video 
      is covered by Guideline 4. Thus, users can load all
      video sources, then control each one independently.
  
  3.3 Allow the user to configure the user agent to render
      animated or blinking text as motionless text.
  
      Proposed: A global configuration to render animated
      or blinking text as motionless text suffices since
      lack of motion addresses the accessibility need and
      since the resulting still text is accessible.
  
  3.4 Allow the user to configure the user agent to render 
      animations or blinking images as motionless images. 
  
      Proposed: A global configuration to render animated
      or blinking images as motionless images suffices since
      lack of motion addresses the accessibility need.
  
  3.5 Allow the user to configure the user agent to not execute
      scripts and applets.
  
      Proposed:  A global configuration to not execute
      scripts and applets suffices since users do not generally
      have access to the text of a script in order to determine
      on a script-by-script basis whether to execute it. I agree
      that some scripts may perform useful tasks at the same
      time others do not within the same page, but I don't think
      that users will need that level of control (turn scripts
      on and off selectively).  Users have access to script text
      under checkpoint 2.1
  
  3.8 Allow the user to configure the user agent to not render images.
  
      Proposed: Allow the user to configure the UA to render
      no images on loading, but thereafter to select individual
      images for rendering. There is not need for a requirement
      to allow the user to turn them back off again selectively.
  
  
  Summary: Except for checkpoint 3.8, I propose that the only
  requirement expressed by these checkpoints be to suppress rendering
  of content type X on loading. Checkpoint 3.8 should allow
  users to turn on images selectively if they were not rendered
  on load.
  
   - Ian
  
  [1] http://www.w3.org/WAI/UA/WD-UAAG10-20000707/#gl-feature-on-off
  [2] http://lists.w3.org/Archives/Public/w3c-wai-ua/2000AprJun/0532.html
  -- 
  Ian Jacobs (jacobs@w3.org)   http://www.w3.org/People/Jacobs
  Tel:                         +1 831 457-2842
  Cell:                        +1 917 450-8783
  

--
Charles McCathieNevile    mailto:charles@w3.org    phone: +61 (0) 409 134 136
W3C Web Accessibility Initiative                      http://www.w3.org/WAI
Location: I-cubed, 110 Victoria Street, Carlton VIC 3053
Postal: GPO Box 2476V, Melbourne 3001,  Australia 
Received on Sunday, 9 July 2000 11:53:23 GMT

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