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Re: Complex Table Examples

From: Laura Carlson <laura.lee.carlson@gmail.com>
Date: Mon, 21 May 2007 07:38:08 -0500
Message-ID: <1c8dbcaa0705210538y64fa4f5cle9906d79fc9404e0@mail.gmail.com>
To: www-html@w3.org, public-html@w3.org

Ian Hickson wrote:

> I have to thank you (quite sincerely) for the amount of research you
> have  done here.

You are most welcome. I sincerely thank you for your comments.

But like Henrik [1] [2], Gregory [3], and Sander [4] [5], I disagree
with you on some incentives and qualifying evidence. Perhaps
incentives as well as types of qualifying evidence should be defined
in the HTML 5 Design Principles.

I proposed that the working group discusses the HTML 5 Design
Principles as one of the next items it tackles and reaches consensus
on them. We all come from different backgrounds with different
experiences. Coming to agreement on guiding principles would aid in
communication and understanding. It would help avoid needless
arguments and churning of issues. Ultimately consensus of guiding
principles and definition of terms would benefit working group
progress.

A few other comments:

>> - Dutch Accessibility Law (R-pd.11.5).
>> http://webrichtlijnen.overheid.nl/besluit/tekst-besluit-en-toelichting/
>> English Translation via Babel:
>> http://www.byteclub.net/wiki/Dutch_Accessibility_Law
>
> My Dutch isn't very good, but I didn't see any mention of the
> headers=""  attribute.

See section R-pd.11.5.

> The e-mail thread quoted above mentions actual [Fidelity Investments]
> examples. Would it be possible to get a hold of actual examples
> (not samples) that demonstrate  its use in the real world?

I'll certainly ask.

> what would be really helpful is an
> explanation of what it is that headers="" does that scope="" does
> not.

WCAG 2 explains it this way, "This technique is used when data cells
are associated with more than one row and/or one column header. This
allows screen readers to speak the headers associated with each data
cell when the relationships are too complex to be identified using the
th element alone or the th element with the scope attribute." [6]

Headers/id attributes are used to specify information per cell. In
complex tables where not all column headers are relevant to all cells
in the column etc the headers will be announced on a per cell basis
when the headers/id technique is used. Like Sailesh  said in his post
[7], "When the labels or headers to be related to  a data cell are not
exactly above it or to its left, or the table uses rowspan / colspan,
one  needs to use the header-id method."  e.g. tide-tables example
[8].

It allows information to be accessed on a per cell basis. Those who
use screen readers listen to data, without any visual cues. When this
technique is used it enables the user to determine which particular
data matches with which particular headers.

> I'd love for someone  -- maybe me, in due course -- to
> do a more in-depth study to check for the  accuracy of these
> assertions.

That would be terrific.

>  1. headers="" is more widely implemented than scope="",

Yes, that is an important factor for graceful degradation as Maciej
states [9]. Due to support issues, Roger Hudson and Russ Weakley's
study [10] found that id/headers are the better method to use. Because
scope is simpler, shorter and less error-prone than id/headers, it
would great if it had better support. It would be great also if all
complex tables could be transformed into simple tables.

Thank you again for your comments.

Best Regards,
Laura

[1] http://lists.w3.org/Archives/Public/public-html/2007May/1060.html
[2] http://lists.w3.org/Archives/Public/public-html/2007May/1038.html
[3] http://lists.w3.org/Archives/Public/public-html/2007May/1059.html
[4] http://lists.w3.org/Archives/Public/public-html/2007May/1056.html
[5] http://lists.w3.org/Archives/Public/public-html/2007May/1056.html
[6] http://www.w3.org/TR/WCAG20-TECHS/#H43
[7] http://lists.w3.org/Archives/Public/www-html/2007May/0516.html
[8] http://broads-authority.gov.uk/boating/navigating/tide-tables.html
[9] http://lists.w3.org/Archives/Public/public-html/2007May/1037.html
[10] http://www.usability.com.au/resources/tables.cfm
___________________________________________
Laura L. Carlson
Information Technology Systems and Services
University of Minnesota Duluth
Duluth, MN U.S.A. 55812-3009
http://www.d.umn.edu/goto/webdesign/
Received on Monday, 21 May 2007 12:52:56 GMT

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