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RE: [#248] Data and layout tables: identifying and marking

From: by way of Wendy A Chisholm <kynnbartlett@yahoo.com>
Date: Wed, 04 Jun 2003 18:22:34 -0400
Message-Id: <>
To: w3c-wai-gl@w3.org


Data tables are used to convey relationships between
the table headers and the table content -- they
associate information along two or more axes.

These are very simple tables, and they are used for
layout because there are no relationships conveyed by
the structure of the tables.

In the first case, there is a relationship that the
phrase "animals" labels what follows; however, this is
more appropriately done in HTML as a header rather
than as table markup. (If there were only one animal,
dog or cat, it would be even more obvious that the
correct markup is an <h[1-6]> tag, not a table.)

In the second example, there are no vertical OR
horizontal axial relationships.

The grouping along two or more axes is vitally
important to data tables.  This is why assistive
technology needs to be able to "poll" each applicable
header (or the first data cell of a column, if none
are marked as a header) to be able to interpret the
axial relationships.

No axial relations equals bad markup equals bad
tables, probably layout tables.  In such a case, you
might as well be using <div> for markup, because
although <div> lacks meaning, at least you're not
BREAKING something.


(PS:  The issue of <br/> validation is a non-issue for
purposes this discussion.)

--- Lee Roberts <leeroberts@roserockdesign.com> wrote:
 > Both of the examples would be layout tables.
 > Although a header are used in example #1, the
 > information does not
 > conform to an understandable data format.
 > Additionally, the <br/> would
 > cause this example to fail validation because HTML
 > 4.01 Transitional was
 > used instead of XHTML.  The image doesn't include
 > alt text.
 > Example 2 simply lays the information out into
 > visually separated
 > sections.  Still no order of linear express is
 > carried through.
 > I'm assuming the content was not intended to be a
 > true representation of
 > a web page.
 > Lee
 > -----Original Message-----
 > From: w3c-wai-gl-request@w3.org
 > [mailto:w3c-wai-gl-request@w3.org] On
 > Behalf Of Chris Ridpath
 > Sent: Wednesday, June 04, 2003 6:52 AM
 > To: WAI WCAG List
 > Subject: [#248] Data and layout tables: identifying
 > and marking
 > Here are links to 2 example tables that may muddy
 > the destinction
 > between layout and data tables:
 > http://www.thunders.ca/tabletest1.html
 > http://www.thunders.ca/tabletest2.html
 > These tables layout text but make use of a header
 > (table1) and caption
 > (table 2).
 > Would you describe them as layout or data tables?
 > Chris

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Received on Wednesday, 4 June 2003 18:22:44 UTC

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