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Table Techniques - Layout (Bug 248)

From: Chris Ridpath <chris.ridpath@utoronto.ca>
Date: Wed, 21 May 2003 16:18:28 -0400
Message-ID: <032a01c31fd6$2bbee8e0$b040968e@WILDDOG>
To: "WAI WCAG List" <w3c-wai-gl@w3.org>

I've compared Kynn Bartlett's summary of TABLE techniques to the WCAG2 TABLE
techniques and listed my observations below. (This is in regard to bug 248
of the WCAG 2 HTML techniques.)

Kynn's summary can be found at:
http://access.idyllmtn.com/tables/

The WCAG 2 table techniques can be found at:
http://www.w3.org/WAI/GL/WCAG20/wcagtech020320.html#tables

Both documents agree that there are 2 general types of tables: layout and
data.
I've heard arguments that all tables are used to organize information so
there is really only one type of table - layout. I believe there is
widespread disagreement with this argument and that we can distinguish
between the 2 types of tables. The WCAG techniques offers that layout tables
are "used to organize data" and layout tables are "used to create a visual
layout of the page". This definition sounds reasonable to me.

Kynn goes further to distinguish between "simple" data tables and "complex"
data tables. A table is complex if it uses colspan, rowspan, nested headers
(more than one row or column header applies to the same data), or more than
one row/column header per table cell. The WCAG techniques treat all data
tables the same. I believe that the WCAG techniques for data tables cover
both "simple" and "complex" tables and there is no need to differentiate.

I've heard it suggested that tables be used for either layout or data but
not both. This appears to be a useful suggestion but I don't see it
mentioned in either document. I suggest the WCAG techniques add a statement
that tables be used for entirely data or layout and not mixed.

LAYOUT TABLES
Style Sheets - Both documents state that authors should use style sheets for
layout and positioning instead of tables (Kynn's also suggests using HTML's
valign and align).
Is it realistic that style sheets be used instead of tables? When is it
necessary to use tables instead of style sheets? I propose that the WCAG
techniques remove the condition of style sheets use unless the techniques
include the conditions under which layout tables may be used. There needs to
be some definition of when layout tables are good/bad compared to style
sheets.

Summary - Kynn states that layout tables should have summaries while the
WCAG techniques do not mention summaries for layout tables.
I've heard from some users that they do not like summaries, especially long
ones, on layout tables. It can hinder them from getting at the page content.
Other users like summaries on all layout tables.
I propose that the technique for layout table summaries is that the first
layout table have a short summary (less than 150 characters, English) that
states the table is used for layout.
Following layout tables should have a short  summary stating "layout table"
or, even better and following our rule on spacer gifs, have a NULL summary
(summary="").

Appearance of table elements - Both documents agree that CSS should be used
to style table elements such as TH.
Is it wrong to use HTML color attributes? Does the WCAG insist on using CSS
over HTML styling? I propose that the WCAG techniques wording be changed to
suggest, not insist, the use of style sheets over HTML styling. Perhaps the
statement about CSS should be removed?

Linearized tables - Both documents agree that tables should make sense when
linearized (read in row order).
Is this still a problem? Don't most screen readers now handle tables well?
What if you want your table be read in column order? What about languages
that read right-to-left or top-to-bottom? How do we test for "make sense"? I
propose that the statement be removed from the WCAG techniques.

The WCAG techniques contain a paragraph "Until user agents render
side-by-side text correctly, provide a linear text equivalent...". I think
that screen readers now handle side-by-side correctly and most authors are
not going to create a linear text equivalent. This "until user agents"
statement should be removed from the techniques.

The techniques also contain several paragraphs regarding word wrap in table
cells. It states that "...developers may minimize the risk of word wrapping
by limiting the amount of text in each cell". Is this still a good
suggestion? How much text should each cell be limited to?

Markup for formatting - Both documents state that markup elements (like TH)
should not be used for formatting text. Makes sense. Kynn goes further to
state that TH, TBODY, THEAD should not be used at all in layout tables. Is
there a reason to use these elements in a layout table? If not then I
propose that a statement be added to the WCAG techniques so that these
elements should not be used in layout tables. I like the idea of a pure
layout table.

Caption - Kynn says not to use. The WCAG Techniques don't say. I propose
that the techniques add a statement to exclude the caption from layout
tables.

Title - Kynn says don't use because it will cause unwanted tooltips. WCAG
Techniques doesn't say. I propose the techniques add a statement to exclude
the title from layout tables. Use the summary instead.

Headers, scope and access - Kynn says don't use. WCAG Techniques doesn't
say. Are there any problems/benefits to using these on layout tables? I
propose we restrict them from layout tables.

Colspan and rowspan - Kynn says to use to enhance the readability of table.
WCAG Techniques don't say. Does this need a mention in the techniques?

I look forward to hearing your comments.

I'll post a message on the techniques for data tables in the next couple of
days.

Regards,
Chris
Received on Wednesday, 21 May 2003 16:37:46 GMT

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