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Re: summarization information delivery options: attribute or element

From: Leif Halvard Silli <xn--mlform-iua@xn--mlform-iua.no>
Date: Wed, 3 Mar 2010 02:08:54 +0100
To: "public-html-a11y@w3.org" <public-html-a11y@w3.org>
Cc: Charles McCathieNevile <chaals@opera.com>, "Gregory J. Rosmaita" <oedipus@hicom.net>, Gez Lemon <g.lemon@webprofession.com>
Message-ID: <20100303020854721880.82bb3c82@xn--mlform-iua.no>
Gez wrote - some replies back:
>>>> If the reason for making it an element is that authors can
>>>> provide richer markup, then I think we're definitely outside
>>>> the territory of a concise overview of the structure of a data
>>>> data table, and more into summary being a long description of
>>>> the table.

To which I listed 3 reasons for making it an element:

>>{1} [to] Avoid to duplicate content from the caption [...]
>>{2} programmatically detectable [WCAG2 programmatic determination]
> {3} keep the table's caption clean/useful [HTML5 blurs it]

W.r.t. {1}: If the purpose is to avoid duplicate content, then it is 
good to keep the table caption and the table summary close to each 
other. Inside the same element seems like the best thing to me. If we 
want to avoid that data rot etc, then it might be good if the table 
summary defaults to visible - at least in editors. W.r.t. {1}, then I 
therefore think a dedicated element as child of <caption> has the best 
effect.

W.r.t. {2}: {2} is is not relevant in contrast to @summary, but is 
relevant in contrast to placing a table summary - or any description - 
inside the <caption> - which is what HTML5 recommends doing: As soon as 
you start to place caption unrelated (description) stuff in the 
<caption>, then it becomes  difficult to avoid that @summary duplicates 
this info. So putting descriptive info inside <caption> very soon 
becomes a reason to not use @summary. I don't say that a text which 
only focuses on the non-visual needs for a table summary, could be more 
useful to "non-visual users", than a more general description would be 
- I simply say that it is very difficult to avoid duplicate content 
this way.

Btw, and also w.r.t. {2}: When I tried to understand 'programmatically 
determine' w.r.t. 'table summary' [1], then I concluded that HTML4 (and 
WCAG2) require that you either use @summary, or that you place the 
table summary text directly in the <caption>. Of course, HTML4 doesn't 
count in that <caption> might contain block elements with long 
descriptions. If this interpretation is correct, then the fact that you 
place the table summary inside the <caption> is not a reason to have a 
dedicated table summary element.

OTOH, when considering technique H39, then perhaps WCAG2 has a more 
narrow understanding of <caption>, than HTML4 has: [2] "The caption 
element identifies the table whereas the summary attribute gives an 
overview of the purpose or explains how to navigate the table."  If so, 
then not only HTML5's lack of @summary, but also HTML5's permission to 
have block elements/descriptions inside <caption> breaks WCAG2. 

W.r.t. {3}: this is also an effect of HTML5's permission for block 
elements (or, indeed, the table summary itself), inside <caption>. 

Conclusion: As soon as we permit no-caption stuff inside <caption>, 
then an element solution becomes attractive.

[1] 
http://www.w3.org/mid/20100302214156005388.40b4e327@xn--mlform-iua.no

[2] http://www.w3.org/TR/WCAG20-TECHS/H39.html

-- 
leif halvard silli
Received on Wednesday, 3 March 2010 01:09:30 GMT

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