W3C home > Mailing lists > Public > wai-xtech@w3.org > August 2008

Re: table headers - clear description of problem

From: Robert J Burns <rob@robburns.com>
Date: Mon, 25 Aug 2008 17:27:12 +0300
Cc: "Ian Hickson" <ian@hixie.ch>, "Steven Faulkner" <faulkner.steve@gmail.com>, "public-html@w3.org WG" <public-html@w3.org>, "W3C WAI-XTECH" <wai-xtech@w3.org>, wai-liaison@w3.org
Message-Id: <99C06362-5C69-4B66-958D-B35B938734BB@robburns.com>
To: Laura Carlson <laura.lee.carlson@gmail.com>

HI Ian,

In addition to the problems I listed previously (repeated below), I  
think the HTML5 draft should also make it clear:

1) that to be conforming a headers attribute idref must reference  
either a TH or TD element's id attribute within the same table and  
sharing at least one indexed slot (as this term is used in the current  
draft) in common. This is a machine-verifiable conformance criterion  
that should help prevent many common headers errors.
2) the precedence when a headers attribute idref conflicts with the  
scope attribute. In other words if the headers attribute references an  
element while the scope attribute indicates the cell corresponding to  
the element should not be associated, then the headers attribute  
should take precedence.

Take care,

> Taking a more forward looking approach, there are several problems  
> with the current HTML5 draft and James Graham/Ben Millard's approach.
> 1) neither adequately account for the need to have headers  
> associated with data cell that are also data cells (key data cell  
> that should be queryable of their own associated headers as well as  
> serving as associated headers for other data cells)
> 2) neither deal with the ambiguities of scope and the fact that  
> scope can easily lead to errant header associations when using the  
> 'colgroup' and 'rowgroup' keywords (see the wiki for more[1])
> 3) the HTML5 draft fails to provide support for the headers  
> attribute which can often make table authoring simpler than relying  
> on scope or other cumbersome structural changes to the table
> 4) neither support the use of the headers attribute for hierarchical  
> headers where a subsection of the table can rely on the header  
> association algorithm to associate data cells with the first  
> (lowest) level of headers while pointing those headers to the next  
> hierarchical level of headers and so on. This facilitates a much  
> simpler way to author complex tables than using scope or headers  
> attributes everywhere. Also my understanding is that this approach  
> is already supported by at least some AT though not specified in  
> HTML4.
> Henri on IRC mentioned the goal of "making simple things easy and  
> complex things possible" with regard to the HTML5 tables[2].  
> However, up until now the goal has been to make really easy things  
> easy and anything more complicated impossible.
> [1] <http://esw.w3.org/topic/HTML/TableHeaderCellScope>
> [2]: <http://krijnhoetmer.nl/irc-logs/whatwg/20080825#l-485>
Received on Monday, 25 August 2008 14:27:54 UTC

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