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Comment on WAI-ARIA Role: Mandatory 'describedby' Too Restrictive

From: Doug Schepers <schepers@w3.org>
Date: Fri, 22 Aug 2008 23:58:45 +0200
Message-ID: <48AF3695.5020202@w3.org>
To: public-pfwg-comments@w3.org, www-svg <www-svg@w3.org>

Hi, ARIA folks-

The SVG WG is discussing the use of a few specific roles for SVG
elements, 'title' and 'desc'.  We think it would be very useful and
appropriate to allow the role values 'description' and 'tooltip' (among
others) on those elements.  However, both of those role values require that:
[[
  Objects with this role must be referenced through the use of a
describedby.
]]

In SVG, we are defining an algorithm that describes the relationship
between the 'title' or 'desc' element and the element or elements they
are describing, based on a parent-child (or more precisely,
container-contained) relationship.  Basically, for most uses, the
'title' and 'desc' elements describe their parent element (which may in
turn simply be a group of elements, in which case the general
description applies to the collection of child elements).

Therefore, the 'describedby' role value is superfluous and possibly
contradictory to the well-structured solution of SVG; similarly, it is
redundant with the HTML 'label' element, with its 'for' attribute.  For
both these cases, the 'describedby' role may (and should) be inferred by
the UA.

Further, requiring this reference may discourage use of roles in these
circumstances, by introducing arbitrary and unnecessary extra work on
the part of the author.

Therefore, our suggestion is that you remove this mandatory stricture,
or soften it to a SHOULD or MAY, or describe a way in which a language
may describe an implicit value for the 'describedby' role based on the
host language's semantics.  You do allude to this last option in
WAI-ARIA: [1]

[[
Build relationships

...

Some relationships are determined automatically from the host language,
such as by using the label tag in HTML.
]]

However, you don't seem to describe the manner in which a language
defines this, and the MUST statement in the roles seems to contradict
the "Build relationships" wording.


[1] http://www.w3.org/TR/wai-aria/#buildingaccessibleapplications

Regards-
-Doug Schepers
W3C Team Contact, WebApps, SVG, and CDF
Received on Friday, 22 August 2008 21:59:21 GMT

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