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RE: Is bobby correct?

From: Jukka Korpela <jukka.korpela@tieke.fi>
Date: Thu, 19 Sep 2002 13:46:06 +0300
Message-ID: <621574AE86FAD3118D1D0000E22138A95BDE63@TIEKE1>
To: w3c-wai-ig@w3.org

Daniel Hillier wrote:

> I just test one of my site using Watchfire's bobby tool and under priority
3
> Accessibility I was told that my site does not meet the requirements for
Bobby
> AAA Approved status as I have not provide a Summary for my table.

First, as a general note, I would like to emphasize that "AAA Approved"
status in Bobby's report, or in any report from an automatic checker, is
_not_ equivalent to actual compliance with WCAG 1.0 at level AAA. Ditto for
other levels. As a simple proof of this, consider the WCAG guideline about
using the clearest and simplest language appropriate for a site's content.
How could any checker verify that? (It's questionable whether anyone can
ever really honestly claim compliance to that rule.) Or consider text
equivalents. If you use alt="foo" (with the literal string "foo" for all
occurrences) for all of your images, Bobby will not complain; it only checks
the presence of an alt attribute, not whether it is actually a text
equivalent to the image. For more arguments, see my notes on accessibility
tools:
http://www.cs.tut.fi/~jkorpela/www/acctools.html
 
As regards to the specific question about summary attributes, it is very
confusing and confused. Guideline 5.5 says:
"Provide summaries for tables. [Priority 3] 
For example, in HTML, use the "summary" attribute of the TABLE element."
Does this mean that you _could_ use "summary" when authoring in HTML but you
might consider other alternatives as well, such as giving a summary in
normal prose before the table? Or does it mean that when authoring in HTML,
the general guideline maps to a specific rule that makes the "summary"
attribute mandatory?

There are different opinions on this. Moreover, it isn't very clear what the
"summary" attribute really _means_. By HTML specification, it "provides a
summary of the table's purpose and structure for user agents rendering to
non-visual media such as speech and Braille". This is somewhat one-sided.
Moreover, the question arises whether it should really summarize both the
purpose and the structure, and why. Shouldn't they be normally explained in
the text of a document and, in part, in the caption element and the heading
cells?

I'd like to refer to a recent thread in comp.infosystems.www.authoring.html
on summary attributes:
http://groups.google.com/groups?th=826c2b3b68c41a27&rnum=1

> The table in question is just there for layout purposes and not data as I
> understood the guild lines you only need to use summary for data tables.

Some people say that "summary" attributes should not be used for layout
tables, only for data tables. But the example that the
http://www.w3.org/WAI/ page itself gives, in its markup, is this:
summary="The following two-column layout can be changed to one column, if
needed for some screen readers, by selecting the 'change column layout'
icon. The first part contains news, information about WAI, and about
participation. The second part lists WAI resources."

If you are obliged to make your page pass Bobby checks, then
summary="Layout table"
is probably something that nobody will strongly complain about. But of
course it isn't particularly brilliant either. And naturally summary="" will
make Bobby happy too.

If the table is used e.g. just to restrict text width to some number of
pixels (a bad move IMHO), then there really isn't any structure to be
expressed, so I'd use summary="" if required to provide a summary attribute.

If the table is used e.g. to present a navigation bar on the left and
content on the right, then - if better options like switching to the use of
CSS instead of such use of table are excluded - I would use something like
summary="First cell: navigational links. Second cell: page content proper"

-- 
Jukka Korpela, senior adviser 
TIEKE Finnish Information Society Development Centre
http://www.tieke.fi/
Diffuse Business Guide to Web Accessibility and Design for All:
http://www.diffuse.org/accessibility.html
Received on Thursday, 19 September 2002 06:46:36 GMT

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