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Layout versus data tables proposal for null summary attribute

From: Phill Jenkins <pjenkins@us.ibm.com>
Date: Thu, 26 Aug 2004 12:54:41 -0500
To: w3c-wai-ig@w3.org, "Michael Cooper" <michaelc@watchfire.com>, Wendy Chisholm <wendy@w3.org>
Message-ID: <OF03FEF97F.A84051C7-ON86256EFC.005C2FD8-86256EFC.00626459@us.ibm.com>
Dear Interest Group member, please send your comments directly to me or 
the list.

Please do not include a discussion about whether to use CSS verses tables 
for layout.  We already agree that CSS is the preferred solution.  Whether 
we use CSS or tables for layout is not the disability issue, what really 
matters is that the reading order is logical when linearized.  For example 
when CSS is off or not available, or when using a magnifier or screen 
reader software to navigate the content in a logical order. 

Proposal:

For devices and user agents that do not support CSS layout and for older 
pages still using tables for layout, the proposal is to recommend a best 
practice for distinguishing between data tables and layout tables by 
including the summary attribute, but leaving the contents empty (null).

Simple Example:

<table title="layout table for navigation" summary="">
<tr><td>Home</td></tr>
<tr><td>more content</td></tr>
</table

Layout tables are those tables in HTML that do NOT have row and/or column 
headings (TH's), do NOT have Captions, and do NOT have other mark-up 
associated with tabular data for which the table markup was originally 
specified. 

Data tables are those tables in HTML that do or should have row and/or 
column headings (TH's), do or should have captions, and do or should have 
other markup, such as summary, scope, and other attributes and elements 
associated with tabular data.

Other proposals included using the title attribute to include the keyword 
"layout".  The disadvantages to this proposal include having the tool tip 
show up on each and every layout table in graphical browsers, the title 
being spoken, depending on settings, when using screen reading software, 
and if we proposed using the null title="", then we wouldn't be able to 
provide additional contextual information for which the title attribute is 
specified.

The proposal to use the null summary="" attribute has the following 
benefits:
1. The null summary="" attribute will not be spoken by screen reading 
software.
2. The summary attribute can be checked for null by authoring tools as a 
convention to indicate the table is for layout.  If we eliminated the 
summary attribute completely from the markup, then there is less of a 
guarantee that the author made a conscience decision to identify the 
articular table as a layout table. 
3. If the keyword "layout" were included in the summary attribute, screen 
reading software would currently speak the term "layout", the contents of 
the attribute,  each time the user navigated to a layout table, which on 
many complex designed pages, would be annoying and too verbose for the 
user.  It would approach the undesirable experience of reading the source 
HTML code. 
4. The user agent could be configured to skip or ignore layout tables 
identified with the null summary="" attribute when navigating.
5. Authoring tools could be more intelligently configured to test for 
reading order in layout tables and correct tabular data markup in data 
tables.

Acceptance of this proposal would require coordination between WCAG 2.0, 
UAAG, ATAG, and assistive technology vendors.  Authors could immediately 
implement this best practice without negative side effects.

Please feel free to forward this proposal to others.  If forwarding to a 
list serv, please copy me.  I will collect all the comments by the end of 
August and reply with an updated proposal to the WAI coordination group.

Thank you,
Phill Jenkins
IBM Research - Accessibility Center
http://www.ibm.com/able
Received on Thursday, 26 August 2004 17:57:23 UTC

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