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

From: Steven Faulkner <faulkner.steve@gmail.com>
Date: Mon, 17 Aug 2009 13:30:15 +0100
Message-ID: <55687cf80908170530w6ba5a2b5s7bb9693b4d353f27@mail.gmail.com>
To: Leif Halvard Silli <lhs@malform.no>
Cc: HTMLWG WG <public-html@w3.org>, W3C WAI-XTECH <wai-xtech@w3.org>
Hi leif,

>Summary: The Consensus Document (hereafter referred to as CD) fails to
discuss <object role="img">

the scope of the discussions was the img element and provision of text
alternatives for it.

(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).
The assertion that describedby is something  "which users must actively ask
for" is not correct. The mechanism is not prescribed to my knowledge. in the
abscence of a short text alternative, the longer text may be announced, or
the presence of the longer text may be announced, which can then be
announced when the user activates a key(s).
   for Q2 to Q4

see above in regards to scope.

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

not currently as role="presentation" is an indication to browsers to not
expose the element via an accessibility API. alt="" does not do this.

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.)

i think not, same as <img role="img"> should not, its redundant, the ,<img>
element is already mapped to accessibility api's by the browser.

  (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?

i would think so as the warning is meant to encourage developers to use
role="presentation" not to indicate alt="" is invalid.

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.)

see anser to Q8 .above

regards
stevef


2009/8/16 Leif Halvard Silli <lhs@malform.no>

> 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
>



-- 
with regards

Steve Faulkner
Technical Director - TPG Europe
Director - Web Accessibility Tools Consortium

www.paciellogroup.com | www.wat-c.org
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Received on Monday, 17 August 2009 12:31:04 GMT

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