# Re: Review of General Flash and Red Flash Threshold text

From: Gregg Vanderheiden <gregg@raisingthefloor.org>
Date: Tue, 12 May 2015 16:07:16 -0500
Cc: GLWAI Guidelines WG org <w3c-wai-gl@w3.org>
Message-Id: <AEB1C457-0DAE-4DB9-8828-3FA13B90236E@raisingthefloor.org>
```Hi Andrew

Pretty good!  But not quite accurate.    You forgot "adjacent in time" in your sentence.     It isn’t    “a" peak and “a" valley but  from one of them and the very next one in time.     That is implied but not quite stated.
You could fix this with and edit  - But they may also not understand  “opposing transitions”  and you don’t explain that yet.

But more basic than the exact wording — I think the way to do this would be to not suggest other wording for the note — (because this would make it out of sync with other standards and regulations) (and because we can’t do that)  but rather to help them understand what is written there.   I would write something that walks them through the concepts presented so they understand them.   Maybe something like:

Thank you Makoto.   Here is what that Note is saying:

If you plot the relative luminance over time - you will see peaks and valleys in the plot.   A transition is the change in value from one Peak to the next valley (or from one valley to the next peak) on the plot.   A flash is two opposing transitions.
Opposing transitions means  transitions going in the opposite direction.
for example -     a transition from a peak to a valley followed and from that valley to the next peak would be a flash
a transition from valley to next peak to next valley   would also be a flash.
If either of these happens 3 times in a second    valley-peak-valley-peak-valley-peak-valley   OR   peak-valley-peak-valley-peak-valley-peak     in any 1 second period - it would fail.
For red flashing you would use a plot of the “relative luminance/color”.

(We have also added this to the Understanding WCAG 2.0 document)

gregg

----------------------------------
Gregg Vanderheiden
gregg@raisingthefloor.org

> On May 12, 2015, at 2:22 PM, Andrew Kirkpatrick <akirkpat@adobe.com> wrote:
>
> Gregg,
> The working group proposed a response to this comment (https://lists.w3.org/Archives/Public/public-comments-wcag20/2015Jan/0009.html <https://lists.w3.org/Archives/Public/public-comments-wcag20/2015Jan/0009.html>).
>
> The comment makes it clear that as this is normative text we are not making a change at this time, but offers a clarification to assist the JIS committee in reviewing their translation.
>
> <proposed comment>
> Thank you for your request. This content is in the Normative glossary and cannot be changed, however we can add a request for clarification of the wording to out "future tasks".
>
> In an effort to help clarify the wording for the purpose of your translation work, the Working Group agreed on this alternate wording for Note 2:
>
> Note 2:
> A transition is the change from a maximum relative luminance value to a minimum relative luminance value (or minimum to maximum). A flash consists of two opposing transitions.
>
> </proposed comment>
>
> You can see the discussion on the development of this proposal at https://github.com/w3c/wcag/issues/69 <https://github.com/w3c/wcag/issues/69>
>
> As you were involved in crafting this language, do you feel that this captures the meaning of the official WCAG 2.0 language?
>
> Original text is:
> Note 2: A transition is the change in relative luminance (or relative luminance/color for red flashing) between adjacent peaks and valleys in a plot of relative luminance (or relative luminance/color for red flashing) measurement against time. A flash consists of two opposing transitions.
>
> Thanks,
> AWK
>
> Andrew Kirkpatrick
> Group Product Manager, Accessibility