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Complex/Simple TABLE

From: Daniel Dardailler <danield@w3.org>
Date: Fri, 23 Oct 1998 14:43:49 +0200
Message-Id: <199810231243.OAA29778@www47.inria.fr>
To: w3c-wai-gl@w3.org

Yesterday on the WAI EO telecon I took an action item to raise on GL
the issue of the unstated definition of simple vs. complex tables that
need additional structural markup (headers, axis, scope).

Currently we have B.3

 B.3. Ensure that tables (not used for layout) have necessary markup
   to be properly restructured or presented by accessible browsers and
   other user agents. [Priority 1]

and the technique 
 B.3.3.
  Where tables have structural divisions beyond those implicit in the
  rows and columns, use appropriate markup to identify those divisions
  (THEAD, TFOOT, TBODY, COLGROUP, the "axis" and "scope" attributes,
  etc.). [Priority 2]

We need to give more details in the technique B.3.3. about what we
mean by simple table that do not require additional structural markup
(where the structure is "implicit in the rows and columns")

In a GL thread back in March, I had proposed the following:

   - if a TABLE only has a single row of header cells at the top
    and/or
   - if it only has a single column of header cells on the left side
     (modulo right-to-left directionality)

In these two cases (which can be combined, or taken down to one-cell
table, as Greg Lowney had mentioned in the thread), given a cell, it
is easy for an agent to find the column and the row header they belong
to without requiring the author to add more markup.

In other words, there is a potential "default" value for the scope
attribute on TH that can be defined as: 
   - if all the cells in a row (TR) are header (TH), 
         then scope defaults to col 
   - if only the first cell in a row (TR) is a header (TH)
         then scope defaults to row

and for some semi-ascii-art examples:

Single header row at the top:

  TR TH TH TH
  TR TD TD TD
  TR TD TD TD

Single header column on the left:

  TR TH TD TD
  TR TH TD TD
  TR TH TD TD

Next step up with headers on both rows and columns (~ below represents
an empty cell):

  TR  ~ TH TH
  TR TH TD TD
  TR TH TD TD
Received on Friday, 23 October 1998 08:43:53 GMT

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