Re: [techs] "Rules" for data tables.

Jim,
The word "all" is the key in the headers-id rule.  When headers-id method  is employed,   scope  and even th are redundant. The th can be retained only for visual effect.
Scope is suggested only for simple tables by the html specs. 
With row/colspan, only headers-id works most reliably.
Is  scope expected to work when rowspan / colspan is used? 
Axis  depends on use of headers attribute and thus can be used only when headers-id method is employed.
What about  title attribute on data cell?  That can also be really useful at times... like conveying that a cell is shaded. Of course screen readers will need to implement support.
I would like to push for use of optional elements like thead and tbody. WinEyes at least announces start of head section and start of body section. JAWS too should do that. It is really useful for data tables and accessibility guidelines must  push for this feature  too. I suppose they  makes table rendering in browser efficient, right?
Sailesh Panchang
Senior Accessibility Engineer 
Deque Systems,11180  Sunrise Valley Drive, 
4th Floor, Reston VA 20191
Tel: 703-225-0380 Extension 105 
E-mail: sailesh.panchang@deque.com
Fax: 703-225-0387
* Look up <http://www.deque.com> *


 
 - I have suggested that to FS.

--- Original Message ----- 
  From: Jim Thatcher 
  To: 'WAI WCAG List' 
  Sent: Wednesday, May 12, 2004 1:06 PM
  Subject: [techs] "Rules" for data tables. 


  At the end of today's call I said I agreed with the idea of the 



  TH Rule (TH technique): TH shall be used for all data tables to identify heading cells and TH shall not be used in Layout Tables. (By the way, if you don't like the way the headings look in TH's, use style get them to look the way you want.)



  I want to add:



  The Summary Rule: Use a non-empty summary attribute on all data tables to summarize the table structure and use summary="" on all layout tables.



  There is a huge difference between these two rules. I contend (with no data) that most data tables are simple tables with headings in row 1 and column 1 - the "and" is important. The TH rule does not help screen readers identify headings in this case because they read from row one and column one anyway. On the other hand, the summary can be immensely helpful presenting a quick view that a sighted user probably obtains by glancing at the table.



  Note the summary can and should present information that will probably be obvious to a person looking at the table - in contrast the Caption/Title identifies the purpose of the table and may not be obvious to someone looking at the table - it also adds to the visual experience.  This suggests the



  Caption Recommendation: Use the caption element to specify the purpose of the data table and do not use the caption element on layout tables.



  The Headers/Id Rule: If there are data cells in a data table whose heading information does not lie in the same row and column as the data cell, then use the header/id markup to identify the heading information for all data cells of the table. 



  The Scope Rule: Use the scope attribute to specify whether a headings applies to a row or column when that information is ambiguous, such as being at a corner of the table or inside the table.



  I have no idea what the axis rule/recommendation is!





  Jim

  Accessibility, What Not to do: http://jimthatcher.com/whatnot.htm.

  Web Accessibility Tutorial: http://jimthatcher.com/webcourse1.htm.