W3C home > Mailing lists > Public > public-html@w3.org > August 2009

Re: feedback requested on WAI CG Consensus Resolutions on Text alternatives in HTML 5 document

From: Leif Halvard Silli <lhs@malform.no>
Date: Sun, 16 Aug 2009 03:13:14 +0200
Message-ID: <4A875D2A.9050602@malform.no>
To: Steven Faulkner <faulkner.steve@gmail.com>
CC: Ian Hickson <ian@hixie.ch>, HTMLWG WG <public-html@w3.org>, W3C WAI-XTECH <wai-xtech@w3.org>
Steven Faulkner On 09-08-15 14.52:

> as part of my work on 
> http://www.w3.org/html/wg/tracker/actions/131, to progress 
> towards consensus by the html wg on the contents of the html 5
>  specification in regards to text alternatives, it would be 
> helpful to get feedback from you and other interested people on
>  the  'WAI CG Consensus Resolutions on Text alternatives in
> HTML 5' document 
> http://www.w3.org/2009/06/Text-Alternatives-in-HTML5


Summary: The Consensus Document (hereafter referred to as CD) 
fails to discuss <object role="img">. Plus some notes on the role 
of @role for IMG.

(1) CD talks about an obligatory short text alternative that will 
be automatically presented to users (e.g. via @aria-labelledby) 
and an optional long alternative which users must actively ask for 
(e.g. via aria-describedby).

	Q1: Hence <img aria-describedby="*"> would not validate unless 
one also added a short text alternative?

(2) OBJECT meets the CD's optimum requirements for short as well 
as long text as it supports "block and inline text structure ... 
and could include rich media types".

	Q2: How does OBJECT fit with the concept of short/long fallback? 
Is the fallback of OBJECT assumed to be short - AKA "automatically 
read" - unless the OBJECT has either @aria-label or @aria-labelledby?

	Q3: Can the mark-up fallback of an OBJECT contain both a short 
and a long text alternative simultaneously? If yes, how?

	Q4: Is the "global @alt" - namely @aria-label[1] permitted for on 
object? (<object aria-label="short text" role="img">)

(4) CD states that role="img" must be the default for the img 
element. Obviously role="presentation" changes the default role.

	Q5: Does alt="" without role="presentation" change the role to 
"presentation"?

	Q6: Should <img role="img" alt=""> validate? (I think no.)

	Q7: Is it supposed to be permitted to literally write <img 
role="img">, even if role="img" is the default? (Otherwise it 
would be impossible to specify, with any certainty, that some IMG 
element is obliged to have a text alternative.)

	NOTE: Validator.nu experimentally implements ARIA but doesn't use 
@role to evaluate the @alt in any way.

(6) The document suggests that alt="" WITHOUT role="presentation" 
triggers a non-critical warning, '(even if @alt="" remains 
technically valid)'.

	Q8: Would lack of role="presentation" in this case be WCAG 2.0 
compliant?

  	Q9: Who would the non-critical warning help? (The CD present 
the warning as new variant of alt="". "Do this and you are valid." 
I don't think we need a warning for the purpose of getting authors 
to get used to the role attribute.)

(5) My take on non-critical warning for <img alt="">:	

Validator should not simply recommend adding role="presentation". 
Because, it might that the IMG in reality requires another role - 
e.g. the right role might be "img"! (Additionally, IMG could 
probably take many other roles than "img" and "presentation" - 
e.g. role="button"?)

The W3 validator uses the notion "tentatively checked" if you e.g. 
use DOCTYPE override. An IMG with alt="" but without 
role="presentation" could be tentatively checked as well. And 
instead of suggesting a specific role, validator could advice the 
author to first select roles and then to revalidate.

	NOTE: To be absolutely consistent, even an IMG with a short text 
alternative present (especially if it is kept inside alt=""), but 
without any role attribute, ought to be considered only 
tentatively valid as well.

[1] http://www.w3.org/TR/wai-aria/#aria-label
-- 
leif halvard silli
Received on Sunday, 16 August 2009 01:13:58 GMT

This archive was generated by hypermail 2.2.0+W3C-0.50 : Wednesday, 9 May 2012 00:16:43 GMT