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Re: input from experience

From: Dave Raggett <dsr@w3.org>
Date: Mon, 13 Oct 1997 08:40:07 -0400 ()
To: Al Gilman <asgilman@access.digex.net>
cc: HC team <w3c-wai-hc@w3.org>
Message-ID: <Pine.WNT.3.95.971013080329.-172877I-100000@hazel.hpl.hp.com>
On Sat, 11 Oct 1997, Al Gilman wrote:

> The header regurgitation was based on header data propagated to
> the browser's runtime data structures for the cell.  It was all
> there all the time with variable levels of what got shown or
> hidden.  This at least requires that one knows which headers go
> with which cells.

This matches my understanding too.

> 
> His idea for how to clearly indicate this header/row association
> is to have attributes in the TABLE declaration (root) itself
> saying which rows contain column heads and which columns contain
> row heads.

This is too limited. It doesn't say how to deal with cases where a
column contains both column and row headers. The scope proposal is
more flexible in this respect and simple to support with the current
desktop word processing software table editing paradigm.

The tables that fit Scott's suggestion can in fact be handled
without any additional markup, using the following algorithm from
section 12.3 of the 4.0 draft spec, see:

http://www.w3.org/MarkUp/Group/9710/WD-html40-971010/struct/tables.html#h-12.3

In the absence of the axes attribute, user agents may search for
pertinent headers according to the following algorithm. The goal of
the algorithm is to find an ordered list of headers. (In the
following description of the algorithm the table directionality is
assumed to be left-to-right.) 

First, search left from the cell's position to find row header
cells. Then search upwards to find column header cells. The search
in a given direction stops when the edge of the table is reached or
when a data cell is found after a header cell.

 * Row headers are inserted into the list in the order they appear
   in the table, e.g., the leftmost headers are inserted before the
   header to their right.

 * Column headers are inserted after row headers, in the order they
   appear in the table. The topmost header is inserted before the
   header below it.

 * If a header cell has an axes attribute, then the headers
   referenced by this attribute are inserted into the list and the
   search stopped in the current direction.

 * TD cells with axis attributes are treated as acting as header
   cells. 

Regards,

-- Dave Raggett <dsr@w3.org> http://www.w3.org/People/Raggett
phone: +44 122 578 2984 (or 2521) +44 385 320 444 (gsm mobile)
World Wide Web Consortium (on assignment from HP Labs)
Received on Monday, 13 October 1997 11:26:45 UTC

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