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Re: Why are nested tables that bad

From: David Poehlman <poehlman1@comcast.net>
Date: Tue, 14 Jan 2003 07:47:54 -0500
To: jim@jimthatcher.com, "'Charles McCathieNevile'" <charles@sidar.org>
Cc: "'Matt May'" <mcmay@w3.org>, "'Jesper Tverskov'" <jesper.tverskov@mail.tele.dk>, w3c-wai-ig@w3.org
Message-id: <00a801c2bbcb$283ae9e0$6501a8c0@handsontech>

I've never seen a table that made sense.

----- Original Message -----
From: "Jim Thatcher" <jim@jimthatcher.com>
To: "'Charles McCathieNevile'" <charles@sidar.org>
Cc: "'Matt May'" <mcmay@w3.org>; "'Jesper Tverskov'"
<jesper.tverskov@mail.tele.dk>; <w3c-wai-ig@w3.org>
Sent: Monday, January 13, 2003 8:17 PM
Subject: RE: Why are nested tables that bad

But Chaals, there is no reason for a person to even try to have a mental
model of the layout tables.  They should be ignored by user and browser
alike. Layout tables do not have to be constructed so that they make
sense, only that the content makes sense when linearized.

Yes, we're talking layout tables, not data tables. I have never seen a
nested data table (that made sense).

508 Web Accessibility Tutorial http://jimthatcher.com/webcourse1.htm.
"Constructing Accessible Web Sites:"  http://jimthatcher.com/news.htm

-----Original Message-----
From: w3c-wai-ig-request@w3.org [mailto:w3c-wai-ig-request@w3.org] On
Behalf Of Charles McCathieNevile
Sent: Monday, January 13, 2003 6:46 PM
To: jim@jimthatcher.com
Cc: 'Matt May'; 'Jesper Tverskov'; w3c-wai-ig@w3.org
Subject: Re: Why are nested tables that bad

On Tuesday, Jan 14, 2003, at 11:29 Australia/Melbourne, Jim Thatcher

> By far the most important thing for this discussion is that nesting of
> layout tables has NO effect, per se, on accessibility. One has to
> that the content linearizes correctly whether nested or not, but I
> would
> bet nesting rarely causes a problem.

There are a couple of buggy browsers that don't handle deeply nested
tables, but in general tables can be linearised even if nested. There
are also systems that allow users to navigate tables properly, rather
than losing the structure of them. So your tables need to be
constructed to make sense - this is more important with data tables
that have real structure than with layout tables where shuffling the
pieces won't have much overall impact on understanding the site.

The effect is one of complicating the navigation, by requiring the user
to hold a mental model that includes several layers of nesting as they
navigate from item to item. This is worse if they have to change mental
models for each page. Except in extreme cases it is only moderately
annoying or imperceptible for most users.


Charles McCathieNevile           charles@sidar.org
Fundación SIDAR                       http://www.sidar.org
Received on Tuesday, 14 January 2003 07:51:03 UTC

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