W3C home > Mailing lists > Public > public-html@w3.org > June 2008

Re: @headers on th too or just td?

From: Robert J Burns <rob@robburns.com>
Date: Thu, 26 Jun 2008 22:56:13 +0300
Cc: "public-html@w3.org WG" <public-html@w3.org>, public-comments-wcag20@w3.org
Message-Id: <35899D34-5284-4400-B019-CD126773CC65@robburns.com>
To: Dan Connolly <connolly@w3.org>

HI Dan,

On Jun 26, 2008, at 9:49 PM, Dan Connolly wrote:

> I did a little investigation into ISSUE-20 table headers...
>  http://www.w3.org/html/wg/tracker/issues/20
> attached are a couple files I was trying to make
> into test cases.
>
> The first one is from relevant WCAG 2 technique that somebody
> referred me to...
>
> H43: Using id and headers attributes to associate data cells with  
> header
> cells in data tables from Techniques for WCAG 2.0
> http://www.w3.org/TR/WCAG20-TECHS/H43.html
>
> I played around with that and validator.nu which led
> me to discover that the current HTML 5 draft allows
> @headers on td but not on th.
>
> "The td element may have a headers content attribute specified."
>  -- http://www.w3.org/html/wg/html5/#the-td
>  Editor's Draft 25 June 2008
>
> I suppose that suffices as far as I know... I can't
> see any particular reason to use @headers on th, though
> this does suggest the example in the WCAG 2 techniques
> should get revised.

For authoring simplicity headers on TH cells is more important than  
headers on TD cells. In fact it would be better for document  
conformance to allow them only on TH cells than to allow them on TD  
cells. A properly specified data / header cell association algorithm  
will already associate data cells with the most immediate header  
cells. Allowing authors to associate those header cells with other  
header cells means that authors only add the IDREF to a few header  
cell rather than maybe thousands of data cells.

I'm not aware if Ben came up within tables that needed headers on the  
TD cells, but I can't come up with any off of the top of my head (as  
long as @headers can be used on TH cells). However, not allowing  
@headers on TD cells means authors have to repeat the same attribute  
value thousands of times in some tables (where it would otherwise be  
once or twice).

Take care
Rob
Received on Thursday, 26 June 2008 19:56:57 GMT

This archive was generated by hypermail 2.2.0+W3C-0.50 : Wednesday, 9 May 2012 00:16:18 GMT