SC 3.2.5 vs. SC 2.2.4 and G75 and G76

SC 2.2.4 Interruptions: Interruptions can be postponed or suppressed by the
user, except interruptions involving an  emergency. (Level AAA) 

SC3.2.5 Change on Request: 
Changes of context  are initiated only by user request or a  mechanism  is
available to turn off such changes. (Level AAA) 
Comment: 
3.2 deals with making Web page content behave in predictable ways and the
emphasis is on consistent layout, navigation and identification. This is in
keeping with the "understanding" principle. 
I believe a change in context caused by  auto updating content (3.2.5)  is
covered by interruptions (2.2.4) that  upset task focus. Such an
interruption or change in context makes it difficult to operate (or even
read) the Web page. So change of context by auto updating content is a
transgression of the "operate" principle than the "understand" principle.
Difficulty in understanding posed by auto updating content is a consequence
of difficulties posed during operation.
On the other hand, changes in context referred to 3.2.1 or 3.2.2 are also
unexpected but are based on user action (focus change / form input) and
certainly hamper understanding. As a consequence it makes operation
difficult.
The supporting techniques for 2.2.4 and 3.2.5 too are identical:
G75 for 2.2.4: Providing a mechanism to postpone any updating of content
G76 for 3.2.5: Providing a mechanism to request an update of the content
instead of updating automatically

I think this is just a play of words and  both SC 3.2.5 and technique G76
can be deleted without any  loss.
Thanks,
Sailesh Panchang
Accessibility Services Manager (Web and Software)
Deque Systems Inc. (www.deque.com)
11130 Sunrise Valley Drive, Suite #140,
Reston VA 20191
Phone: 703-225-0380 (ext 105)
E-mail: sailesh.panchang@deque.com

Received on Thursday, 10 July 2008 19:18:15 UTC