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RE: parsing issue with SC 2.3.2?

From: Gregg Vanderheiden <gv@trace.wisc.edu>
Date: Wed, 30 Nov 2005 17:19:12 -0600
To: "'Tim Boland'" <frederick.boland@nist.gov>, <w3c-wai-gl@w3.org>
Message-ID: <012001c5f604$7a886b70$ee8cfea9@NC6000BAK>

Good catch.

This should say

"violates neither the general nor the red..."

If no objections I will bring up with the WG for a change. 


 -- ------------------------------ 
Gregg C Vanderheiden Ph.D. 
Professor - Ind. Engr. & BioMed Engr.
Director - Trace R & D Center 
University of Wisconsin-Madison 

-----Original Message-----
From: w3c-wai-gl-request@w3.org [mailto:w3c-wai-gl-request@w3.org] On Behalf
Of Tim Boland
Sent: Wednesday, November 30, 2005 2:46 PM
To: w3c-wai-gl@w3.org
Subject: parsing issue with SC 2.3.2?

SC 2.3.2 states:

"Content does not violate general flash threshold or red flash threshold"

How should this sentence be parsed?  What rules of precedence should apply?
Is the parsing "(Content does not violate general flash threshold) or 
(content does not violate
red flash threshold)" or is the parsing "Content does not violate (both 
general flash threshold and red
flash threshold)"?

For the former parsing (using Boolean algebra approach?), if one of the 
clauses in parentheses is true, then
the entire sentence is true (x OR y = 1 if x=1 or y=1 or both).  For the 
latter parsing, the clause in parentheses
constitutes an AND operation (condition) (meaning that satisfaction of both 
thresholds has to be met simultaneously?)
(x AND y=1 if and only if both x=1 and y=1 at the same time), so the 
sentence is only true if content does not
violate both clauses at the same time.

Which parsing is meant by the WCAG WG for SC 2.3.2?    This question may 
need to be answered for testability
of this SC..

I investigated the SC2.3.2 Guide Document for this SC, which in the 
"intent" section seems to imply to me
that the red flash threshold is a "special" threshold above and beyond the 
general flash threshold.  If content satisfies the
general flash threshold requirement, does it meet this SC (general flash 
threshold is defined in terms of a "sequence", and
red flash threshold is defined in terms of a "transition")?    Or does 
content need to meet both the general flash threshold and the red flash 
threshold simultaneously in order to meet this SC?    What is the 
relationship (if any) between general flash threshold and red flash
threshold?  Are these "independent" guidelines for the broadcast industry, 
or does one build upon the other in some sense?

Perhaps some clarification is needed (maybe in the Guide Document?), as a 
novice reader may find the parsing of the subject sentence 
confusing?  Apologies if this question is already answered somewhere..

Thanks and best wishes
Tim Boland NIST
Received on Wednesday, 30 November 2005 23:19:24 UTC

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