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mechanism to provide a summary of high density information easily discernible from a cursory visual glance

From: Robert J Burns <rob@robburns.com>
Date: Wed, 11 Jun 2008 13:36:23 +0200
Message-Id: <C9382EF7-DA22-434C-913C-DE64B895F0EF@robburns.com>
To: HTML Issue Tracking WG <public-html@w3.org>

Rather than putting this in terms of a summary attribute or a summary  
element, let me simply say we need a facility to provide a summary of  
tables (some tables) for non-visual (or low-vision or color blind)  
consumers of table contents. A summary attribute or element seems like  
the obvious mechanism to accomplish this, but I'm sure we'd all be  
open to other solutions/ideas. However, it is important to understand  
the problem solved by summarizing the visual aspects of a table.

Ian says: “If the problem is that the table is especially complicated  
and needs a summary to be understood, why disenfranchise the sighted  
users by only showing the summary to disabled users? It seems like the  
table would be better served by a paragraph before or after the table  
explaining it for everyone.”[1]

This reminds me of an episode of the Simpsons when Homer spent a day  
in his father’s nursing home. He feels great envy for the easy life of  
the elderly there like one who has a wheelchair to which Homer says:  
“a chair with wheels, and here I am using my own legs like a sucker.”  
Later he sees another nursing home resident on a respirator and says[2]:
   Homer: Hey, what's lucky hooked up to?
   Nurse: A respirator. It breathes for him.
   Homer: And here I am using my own lungs like a sucker.

Tables are an inherently visual way to display information of a fairly  
high density: especially with the use of borders, background colors  
and text/font attributes, particular relations of the data in the  
table can be quickly gleaned from a cursory glance at the table. For  
tables which possess these aspects, a summary is crucial for users who  
cannot visually consume the table as a 2-dimensional grid.

So while the summary attribute may provide information that sighted  
users might find useful as well, it is generally for information that  
sighted users do not need: this should be clearly stated in the  
document conformance and the default presentation should not display  
the information for visual UAs (or the visual presentation of a hybrid  
UA). There are ways that visual UAs could present the summary  
attribute rather than including the information in the document  
viewport presentation[3].

The problem is that, if we only provide authors a mechanism to display  
summaries about the table, authors will be reluctant to include  
information that is already obvious to the sighted user: instead  
simply omitting the information because it doesn’t achieve the focus  
they’re trying to achieve for a visually-centered presentation of the  
document. In other words it is important semantic information about  
the document, but the author decides to omit it because it is contrary  
to the visual presentation goals of the authors.

I hope this clarifies the importance of table summaries.

Take care,

[1]: <http://lists.w3.org/Archives/Public/public-html/2008Mar/0215.html>
[2]: <http://www.imdb.com/title/tt0096697/quotes>
[3]: <http://esw.w3.org/topic/HTML/RicherUIAccessToHTMLData>
Received on Wednesday, 11 June 2008 11:37:06 UTC

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