- From: Gregg Vanderheiden <gv@trace.wisc.edu>
- Date: 2009年3月19日 08:54:03 -0500
- To: Roberto Scano (IWA/HWG) <r.scano@webprofession.com>
- Cc: "'WCAG'" <w3c-wai-gl@w3.org>
- Message-Id: <68B36A19-0B64-43F2-B89C-DBC17D8EE658@trace.wisc.edu>
Hi Roberto the comment is correct but poorly worded. We will need to fix that at level A you need to pass the General and Red Flash Thresholds. these thresholds give you the option. EITHER - don't flash more than 3.5 times in any one second period OR - the flash must be smaller or dimmer than a threshold. At level AAA it says that you must no flash more than 3.5 times in any one second period. Period. Technique G19 says - just don't flash less than 3.5 time in any one second period. This will indeed pass both the Level A and the Level AAA Success criteria. But it is more strict than Level A requires (since level A does allow more than 3.5 flashes if they are small or low contrast enough. Also the word "failure" is confusing since it is referring to things that would fail the thresholds - but it makes you think it is talking about the "common failures" So we should change the note to read something like Note 1: This technique is stricter than the Level A Success Criteria since the Level A success criteria 2.3.1 allows more than 3.5 flashes in one second if they are small or low contrast enough. But having no more than 3.5 flashes within any one second period would meet the Level A success criteria (and the Level AAA success criteria 2.3.2 as well). It is also much easier to test. Most content does not flash at all and even content that blinks does not blink this fast except on rare occasions. Therefore, in order to avoid having to carry out the more complex testing specified by the Level A Success Criteria 2.3.1, one could follow this technique and ensure that content only flashes one, two, or at most three times in any 1-second period. Thanks for catching this. Gregg ----------------------- Gregg Vanderheiden Ph.D. Director Trace R&D Center Professor Ind and Biomed Engr University of Wisconsin-Madison On Mar 19, 2009, at 8:04 AM, Roberto Scano (IWA/HWG) wrote: > Hi all, i think there is a mistake here: > > > http://www.w3.org/TR/2008/NOTE-WCAG20-TECHS-20081211/G19 > > > Note 1 said: > > --- > Note 1: This technique is stricter than the Level 1 Success Criteria > but is > easier to test and can be used to meet the Level 1 Success Criteria > because > all failure thresholds in the Level 1 Success Criteria involve > flashing 3.5 > flashes or more within one second. Most content does not flash at > all and > even content that blinks does not blink this fast except on rare > occasions. > Therefore, in order to avoid having to carry out the more complex > testing > specified by the Success Criteria, one could follow this technique > to ensure > that content only flashes one, two, or at most three times in any 1- > second > period. > --- > > But this Is a level 1 success criteria and i don't find any failure > for the > cited 3.5 flashes: > > http://www.w3.org/TR/UNDERSTANDING-WCAG20/seizure-does-not- > violate.html > > > > --- > Roberto Scano (rscano@webprofession.com) > International Webmasters Association / HTML Writers Guild > > > > >
Received on Thursday, 19 March 2009 13:54:45 UTC