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RE: Updating 2.4, re-revised

From: Charles McCathieNevile <charles@w3.org>
Date: Thu, 31 May 2001 00:36:27 -0400 (EDT)
To: Gregg Vanderheiden <gv@trace.wisc.edu>
cc: "'Adam Victor Reed'" <areed2@calstatela.edu>, <w3c-wai-gl@w3.org>
Message-ID: <Pine.LNX.4.30.0105310035350.6049-100000@tux.w3.org>
Hmm. Effectively there is an important implementation question - how long is
the minimum time before asking people if they need more time?

Charles McCN

On Wed, 30 May 2001, Gregg Vanderheiden wrote:

  I'm not sure there should be an absolute timeout ban.    But I agree there
  should be something on timing.

  For example,  the case cited had a 15 minute timeout.  I don't know of
  anyone who cannot respond in 2 minutes.      A person may need more than 15
  min to understand a page,  but that is different than not being able to
  respond.  The site could for example,  allow 15 min to pass and then simply
  ask "are you there?  Do you need more time?".   It could also reset the 15
  min each time the person did something like scroll.    In both cases it
  would allow a person to be on line for hours on a single page.  But they
  would have to indicate that they were there every so often.   If they left
  or shut off their computer etc, the system would time them out after 15 min
  of getting no activity or any acknowledgement from them.

  That would change 2.4 to


  2.4    Do not limit the time that a user has to understand or interact with
  your content.  If a timeout is needed, provide the user with a means to
  bypass or extend the time.
          * Use automatic refresh and delayed redirection only when
            necessary to bring superceded content up to date.
          * Content must cooperate with user agent mechanisms for
            preventing motion (including flicker, blinking, flashing,
            self-scrolling etc) and for control of the rate at which
            motion occurs.

  I WOULD DELETE THE FLICKER COMMENT HERE - AS IT CONFUSES THE SITUATION.
  FLICKER IS BARRED ELSEWHERE
   Note that flicker effects can cause
            seizures in people with photoepilepsy.


  Gregg


  -- ------------------------------
  Gregg C Vanderheiden Ph.D.
  Professor - Human Factors
  Depts of Ind. and Biomed. Engr. - U of Wis.
  Director - Trace R & D Center
  Gv@trace.wisc.edu, http://trace.wisc.edu/
  FAX 608/262-8848
  For a list of our listserves send "lists" to listproc@trace.wisc.edu


   -----Original Message-----
  From: 	w3c-wai-gl-request@w3.org [mailto:w3c-wai-gl-request@w3.org]  On
  Behalf Of Adam Victor Reed
  Sent:	Wednesday, May 30, 2001 10:36 PM
  To:	w3c-wai-gl@w3.org
  Subject:	Updating 2.4, re-revised

  Time-outs are a real barrier, so leaving them out of the guidelines is
  not a solution. If time-outs are needed for economic or security
  reasons, the provider ought to provide a bypass - for example, by
  letting disabled users register and get a "bypass timeouts" cookie.
  So I'll try again:

  2.4 Do not limit the time that a user may need to understand or
  interact with your content.
          * Provide disabled users with a way to bypass any demand to
            respond within a preset period.
          * Use automatic refresh and delayed redirection only when
            necessary to bring superceded content up to date.
          * Content must cooperate with user agent mechanisms for
            preventing motion (including flicker, blinking, flashing,
            self-scrolling etc) and for control of the rate at which
            motion occurs. Note that flicker effects can cause
            seizures in people with photoepilepsy.

  --
  				Adam Reed
  				areed2@calstatela.edu

  Context matters. Seldom does *anything* have only one cause.


-- 
Charles McCathieNevile    http://www.w3.org/People/Charles  phone: +61 409 134 136
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Received on Thursday, 31 May 2001 00:36:31 GMT

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