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(unknown charset) Table Summary Change Proposal

From: (unknown charset) Leif Halvard Silli <xn--mlform-iua@xn--mlform-iua.no>
Date: Sun, 28 Feb 2010 21:21:59 +0100
To: (unknown charset) public-html-a11y@w3.org
Message-ID: <20100228212159255720.86c6d000@xn--mlform-iua.no>
I have reworked the CP that I offered on Saturday [1], with a new one:

http://www.w3.org/html/wg/wiki/ChangeProposals/tableSummaryProposal

This new proposal is simpler: It allows up to two caption elements, as 
long as one of them is pointed to via aria-describedby. The proposal 
also designates the role of aria-describedby and aria-labelledby 
differently. 

	(Because ... I consulted the ARIA spec ... and @aria-labelledby 
basically can be used to point to a caption element. I am still 
interested in this subject though ... It could still be that 
aria-labelledby="caption-with-summary" would be more meaningful. **I am 
very interested in comments about this.**)

A <caption> which is pointed to via aria-describedby, is considered a 
table summary and must not contain any block level elements. If there 
are two caption elements, then the one with the 'table summary' content 
should appear after the other <caption> in the source code (as this 
typically has the effect of hiding it in visual user agents).

'Table summary' is described in the proposal as a technical term with 
the meaning described in WCAG20 technique H73 about @summary, namely 
something (a @summary or a <caption>) which "describes the table's 
organization or explains how to use the table" and which is also 
*primarily* aimed at user of non-visual user agents.

The proposal also describes how to identify 'table caption' and 'table 
description' inside a <caption> with block elements (as permitted in 
the HTML5 specification draft). The proposal also restricts the 
permitted block elements inside <caption>.

The proposal discerns between 'table description' and 'table summary' 
and says that 
	a) when <caption> contains a 'table description', then the 'table 
summary' could be placed inside the 'table description'
	b) but it also says that a) has the effect of not revealing the 'table 
summary' to non-visual user agents as a 'table summary'. (Because we do 
not have, in ARIA, something like a @aria-summary attribute, that could 
have been used to point to such information.) 
	c) thus the proposal also says that even when <caption> contains as 
'table description', there might still be a need for a 'table summary'. 

The proposal does not say that a 'table summary' should appear as part 
of the 'table description'.
Even if it is not (yet) expressed in the proposal, I think it is 
acceptable to place the 'table summary' inside the 'table description' 
inside a <caption> containing block elements, as long as the 'table 
description' there is not overly complex.

Comments, ideas, suggestions of improvements are welcome. 

Questions: 

	* What about not requiring aria-describedby, as long as the caption 
with the 'table summary' appears *after* the other <caption>?
	* aria-labelledby vs aria-describedby - see above.

[1] http://lists.w3.org/Archives/Public/public-html-a11y/2010Feb/0612
-- 
leif halvard silli
Received on Sunday, 28 February 2010 20:22:34 GMT

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