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

From: Ian Jacobs <ij@w3.org>
Date: Sat, 08 Jul 2000 13:06:19 -0400
Message-ID: <39675F8B.C5ECA60A@w3.org>
To: w3c-wai-ua@w3.org
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
Received on Saturday, 8 July 2000 13:06:21 GMT

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