Re: [1.2T LC] @aria-foo atributes: un-prefixed, forbidden? (ISSUE-2090)

Hi, Al-

You're correct that the SVG 1.2 Tiny spec, by itself, does not allow the
unprefixed aria-* attributes on elements (though prefixed attributes
would still work, since they fall out of the XML Namespaces model
already integrated into SVG).

The SVG WG did consider this seriously over the course of multiple
conversations, and there are several reasons that we didn't include
support for the unprefixed ARIA attributes to this spec:

1) The WAI-ARIA spec is not yet stable, so we could not normatively
reference it.

2) The "aria-*" syntax, though implemented in some browsers, is not yet
part of the HTML5 spec; since that spec is the sole reason for the
exceptional syntax, it seemed imprudent for us to add it, in case a
future incompatibility arose later.

3) The RelaxNG schema would need to be developed (I've seen Henri
Sivonen's schema for HTML5 [1], and I think that SVG's would be much
simpler, but we haven't had time to look into all the details,
especially any gotchas that might arise).

4) Most importantly, we don't have 2 conforming SVG 1.2 Tiny
implementations of that syntax that we can reference in our
Implementation Matrix, and we cannot afford to wait for them (especially
since ARIA itself is not yet done, and we don't know what changes might
happen in the future).

We did add the 'role' attribute because it has a general use beyond ARIA
that we could justify, and the implementation burden was very low.  We
took this step to lay the groundwork for future accessibility
development, and to demonstrate our good faith in committing to
integrating ARIA into SVG.

Our intent, as we stated before [2], is to work with WAI to develop a
separate module that integrates ARIA with SVG more completely, including
a set of roles for SVG diagrams.  The RelaxNG schema would belong in
this spec.

In the meantime, nothing stops an author from using ARIA with SVG
(assuming there are implementations that support it).  Any aria-*
attributes, and their values, would still be present in the DOM; the
only issue is that the document would not validate against the SVG 1.2
Tiny schema.  When we have developed a new schema that does include ARIA
support, such documents could be validated against that schema, and such
an extended schema will not conflict with existing SVG specs.  In fact,
it would be good for authors to at least experiment along these lines,
to ensure that we have our bases covered before finalizing something in
a spec.

I hope that this explains the situation and allays your concerns.
Please do let us know promptly either way.


[1]
http://lists.w3.org/Archives/Public/public-schemata-users/2008May/0001.html
[2] http://lists.w3.org/Archives/Public/www-svg/2008Jun/0040.html

Regards-
-Doug

Al Gilman wrote (on 10/1/08 3:02 PM):
> 
> ** problems statement
> 
> <quote
> 
> Unprefixed attributes on elements in the SVG namespace must not be used
> for extensions.
> 
> </quote>
> 
> But that's exactly what WAI-ARIA asks host languages to allow; that the
> aria-foo attributes appear un-prefixed:
> 
> <quote
> 
> The names of these attributes do not have a prefix set off by a colon;
> in the terms of Namespaces they are "unprefixed attribute names."
> 
> </quote>
> 
> When I ran our approach through the Hypertext CG, I believe the feedback
> I got was that your group had reviewed this and were willing to live
> with the un-prefixed, aria-foo attribute names for the WAI-ARIA states
> and properties.
> 
> So I hope that this is just a matter of incomplete editing, not a latent
> disagreement about the host language embedding approach for ARIA.

Received on Thursday, 9 October 2008 07:15:11 UTC