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Re: Deliverable for Action 72 @headers

From: Laura Carlson <laura.lee.carlson@gmail.com>
Date: Sun, 24 Aug 2008 11:07:19 -0500
Message-ID: <1c8dbcaa0808240907i38ff2f04nc544b267e5eb6f97@mail.gmail.com>
To: "HTML WG" <public-html@w3.org>
Cc: "James Graham" <jg307@cam.ac.uk>, "W3C WAI-XTECH" <wai-xtech@w3.org>, "Gez Lemon" <gez.lemon@gmail.com>

Gez wrote:

> I just wanted the conversation based
> around the headers example if we're going to talk about the headers
> attribute. Although nested header elements do not feel right, I
> wouldn't oppose the idea, as it could provide the relationship
> necessary to work. All I care about is that we're able to markup data
> tables accessibly.

Yes, currently hierarchical headers are not allowed in HTML5, this
means that conceptual headers (cells that contain data and have their
own header, but act as a header for other cells in the table) must be
marked up as a td. As these cells are conceptually headings, the
headers attribute should be able to reference the id attribute of
these cells.

One way or another, HTML 5 needs a mechanism that enables people using
non-visual user agents to determine which particular data matches with
which particular headers in complex tables like:
http://juicystudio.com/wcag/tables/complexdatatable.html

The way headers are currently specified in HTML 5, only allows the
simplest of data tables to be defined accessibly, which defeats the
purpose of getting the headers attribute into the specification at
all, because it can't do anything that most ATs don't already do by
default. Currently implementation is such that complex tables cannot
be created using the headers attribute. The headers attribute in the
current specification is of little use, as it can only reference a th,
and the th cannot be a hierarchical th. Without being able to
associate header cells to data cells, screen reader users will either
have great difficulty, or find it impossible, to orientate themselves
in complex data tables.

The proposed two step solution in the Wiki is

1. Reinstate headers/id AND their functionality into the spec by
specifically stating that headers are allowed to reference a td.
Reword the current definition of the headers attribute so that each of
the space separated tokens must have the value of the ID value of a th
or td element. See the ACTION 72: @headers rewrite deliverable:
http://esw.w3.org/topic/HTML/Action72Headers

2. Introduce a new type of table cell which automatically acts as both
a header and a data cell without any explicit accessibility attributes
or without any explicit associations (as the editor proposed in bug
5822).
http://www.w3.org/Bugs/Public/show_bug.cgi?id=5822#c14
NOTE: This step DOES NOT help describe irregular tables and it doesn't
work right now with AT, whereas headers/id does.

PFWG's advice over a year ago in June 2007 stated, "A disability
constituency currently uses and depends on this feature: anyone
offering to remove it should be expected to demonstrate that the
replacement works better and is in service. Dropping 'headers' because
'scope' could afford the same semantics in 'most of the cases' is a
wrong decision; now or, taken in isolation, for the future. The
headers/id technique provides functionality today. If it is to be
worked out of the system, it should not be an abrupt drop. Transition
it out with something better in an orderly and graceful manner."
http://lists.w3.org/Archives/Public/public-html/2007Jun/0145.html

Best Regards,
Laura

-- 
Laura L. Carlson
Received on Sunday, 24 August 2008 16:07:55 GMT

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