Thread Subject: "Time limit" provisions of other standards.

From: Gregg Vanderheiden
Date: Wed, Dec 13 2006 12:10 AM

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This email regarding timing was requested by the telecom group. I'm copying
the General and Soft-Web groups FYI









Here is the current wording of 3 other standards. They all have the same 3
basic provisions since they have been trying to harmonize with each other.



In all of these



1) Deactivate always works - but is not practical in some applications
(security for example).



2) Adjust is usually used for short time limits like key-repeat etc where it
doesn't make sense to ask for it to tell you when it is about to time out
(and repeat a key)



3) Extend - is usually used with ATM and other devices that use timeout for
security. They can't just make the time limit longer since it would reduce
the security of the person with a disability using the ATM (if they walked
away the ATM would stay logged in to them for 10 times as long before
resetting). This way the user can have 10 times as much time to complete
the task if needed, but if they leave, it shuts down in the normal security
time window.



In looking at these I see one thing was left out of "extend". It must
restore the person to where they were when the timeout occurred or they
might just get to the same place 10 times - and get no further (if it made
them start over each time). (Sort of a 'groundhog's day' situation.) SO
I would suggest an edit to "EXTEND" so that it reads:

* Extend: the user is warned before time expires and given at least
20 seconds to extend the time limit to with a simple action (for example,
"hit any key") that returns them to the point where they were interrupted,
and the user is allowed to extend the time limit at least ten times; or




WCAG version


{2.2.1 is part of Conformance at Level A. 2.2.4 is part of Conformance at
Level AAA }

2.2.1 Timing: For each time limit that is set by the content , at least one
of the following is true:

* Deactivate: the user is allowed to deactivate the time limit ; or

* Adjust: the user is allowed to adjust the time limit over a wide
range that is at least ten times the length of the default setting; or

* Extend: the user is warned before time expires and given at least
20 seconds to extend the time limit with a simple action (for example, "hit
any key"), and the user is allowed to extend the time limit at least ten
times; or

* Real-time Exception: the time limit is an important part of a
real-time event (for example, an auction), and no alternative to the time
limit is possible; or

* Essential Exception: the time limit is part of an activity where
timing is <http://www.w3.org/WAI/GL/WCAG20/#activity-timingdef> essential
(for example, competitive gaming or time-based testing) and time limits can
not be extended further without invalidating the activity.

activity where timing is essential

activity where timing is part of the design of the activity and removal of
the time dependency would change the functionality of the content



2.2.4 No Timing: Except for real-time events
<http://www.w3.org/WAI/GL/WCAG20/#real-time-eventsdef> , timing is not an
essential part of the event or activity presented by the content.








HFES-200







8.3.7 Enable user control of timed responses (Level 1)


Unless limits placed on the timing of user responses are essential to
maintaining the integrity of the task or activity or are based on real life
time constraints (e.g. an auction), software should allow users to adjust
each software-specified user response time parameter in one or more of the
following ways:

1) the user is allowed to deactivate the time-out, or;

2) the user is allowed to adjust the time-out over a wide range which
is at least ten times the length of the default setting, or;

3) the user is warned before time expires, allowed to extend the
time-out with a simple action (for example, "hit any key") and given at
least 20 seconds to respond.

EXAMPLE: A logon prompt requires the user to enter their password within 30
seconds. Show the remaining time on the screen and provide a control to
stop the time decrementing.






ISO 9241-171




Enable user control of timed responses

Unless limits placed on the timing of user responses are essential to
maintaining the integrity of the task or

activity or are based on real life time constraints (e.g. an auction),
software shall allow users to adjust each

software-specified user response time parameter in one or more of the
following ways:



- the user is allowed to deactivate the time-out, or;



-the user is allowed to adjust the time-out over a wide range which is at
least ten times the length of the

default setting, or;



- the user is warned before time expires, allowed to extend the time-out
with a simple action (for example,

"hit any key") and given at least 20 s to respond.



EXAMPLE A logon prompt requires the user to enter their password within 30
s. Show the remaining time on the

screen and provide a control to stop the time decrementing.




Gregg

------------------------

Gregg C Vanderheiden Ph.D.
Professor - Depts of Ind. Engr. & BioMed Engr.
Director - Trace R & D Center
University of Wisconsin-Madison
< <http://trace.wisc.edu/> http://trace.wisc.edu/> FAX 608/262-8848

DSS Player at <http://tinyurl.com/dho6b> http://tinyurl.com/dho6b

<http://trace.wisc.edu:8080/mailman/listinfo/>

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