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Re: summarization information delivery options: attribute or element

From: Leif Halvard Silli <xn--mlform-iua@xn--mlform-iua.no>
Date: Tue, 2 Mar 2010 16:58:29 +0100
To: Shelley Powers <shelleypowers@burningbird.net>
Cc: John Foliot <jfoliot@stanford.edu>, 'Joshue O Connor' <joshue.oconnor@cfit.ie>, 'Laura Carlson' <laura.lee.carlson@gmail.com>, 'Gez Lemon' <g.lemon@webprofession.com>, "'Gregory J. Rosmaita'" <oedipus@hicom.net>, public-html-a11y@w3.org
Message-ID: <20100302165829835745.7f162a47@xn--mlform-iua.no>
Shelley Powers, Tue, 02 Mar 2010 07:59:42 -0600:
> Leif Halvard Silli wrote:
>>> Though technically not a _new_ element [1], using two captions on a 
>>> table is not, I believe, an enhancement that will degrade 
>>> gracefully with older user agents.
>>> 
>>> Firefox doesn't print out the second caption, as Leif states in his 
>>> change proposal, but that's not a behavior we can count on.
>> 
>> Right. We need support in more than one UA.
>>   
> Unfortunately, the second caption is not backwards compatible. It 
> breaks with existing and older browsers.

I think you are rushing to conclusions. On this page, I have both 
hidden and shown second captions, and it works for Webkit, IE, Opera 
and Firefox:

http://målform.no/html5/caption+role


You could test it in NVDA if you want, If NVDA doesn't read even the 
*visible* second <caption>s, then we for sure have a problem. As long 
as NVDA reads the visible captions, then trick to serve a hidden 
caption to NVDA is some variant of: 
	a) make second caption visible via CSS, and then use
	b) caption+caption{position:absolute;left:-9999cm} 
	  (or something similar) to visually hide it. (I will soon publish a 
demo of this.)

I am well aware that some UAs hide a second caption while others reveal 
it. So a second caption *must* be followed by advice about how to use 
CSS to hide/reveal it. Isn't that acceptable? How is that different 
from introducing a new element, of which HTML5 has quite a few, and 
which also needs advice to authors about how to style it?

Some of us have debated a <summary> element directly as child of 
<table>. The issues with that are also related to visibility (I think), 
but even more is it related to whether the UA spits the element out of 
<table> or not - i.e. it removes it from what it is supposed to be 
related to.

>>> Opera does print out the second caption. Safari and Chrome do not. 
>>> IE does. NVDA says one caption when the page is loaded in Firefox. 
>>> NVDA says both captions, when the page is loaded in IE.
>>> 
>>> The results we will get for a second caption are unreliable.
>> 
>> My CP specifically says that we must investigate what the best CSS 
>> is. It sounds from your description like NVDA behaves very much like 
>> VoiceOver does: It only reads that what is somehow visible. 
>> VoiceOver e.g. doesn't read the content of @summary. Thus it reads 
>> the second caption, but only when it is somehow visible.
>> 
>> So, can you also tell us how NVDA behaves with regard to @summary?
> 
> It worked on mouse over. It might work in other ways, but that was 
> the only one I tried. I'm still pretty new to NVDA.

OK. Thanks for mentioning NVDA though. I will also try to test it 
myself as soon as I get time.
-- 
leif halvard silli
Received on Tuesday, 2 March 2010 15:59:10 GMT

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