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RE: [text] starter draft of clarification on alt validation, for discussion

From: Judy Brewer <jbrewer@w3.org>
Date: Fri, 29 Apr 2011 22:35:03 -0400
Message-Id: <E1QG05k-0006IB-6x@maggie.w3.org>
To: Paul Cotton <Paul.Cotton@microsoft.com>, "Sam Ruby (rubys@intertwingly.net)" <rubys@intertwingly.net>, "Maciej Stachowiak (mjs@apple.com)" <mjs@apple.com>, Janina Sajka <janina@rednote.net>
Cc: HTML Accessibility Task Force <public-html-a11y@w3.org>
Paul,

At 10:33 PM 4/29/2011 +0000, Paul Cotton wrote:
>Can you explain to me what you expect to do with this [DRAFT] text 
>when you complete it?

I believe you're already familiar with this work through reports in 
HTML A11Y TF meetings and minutes, and Janina's reports in the HTML 
WG meeting. Please see our responses to your specific questions below 
and let us know of other questions as needed.

>Is the [DRAFT] text to be sent to public-html@w3.org for discussion 
>by the WG?
>
>Or, is the [DRAFT] text going to be sent to the WG Chairs?

To the WG Co-Chairs with cc to the WG.

>If you plan to send it to the WG Chairs what actions are you hoping 
>to cause to occur?  Are you going to be formally asking for ISSUE-31 
>or ISSUE-80 to be re-opened?

We will be providing the clarifications that the Text Alternatives 
Sub-Group is preparing and formally asking for these issues to be re-opened.

>If you want one or more of these ISSUEs re-opened do you plan to 
>provide a change proposal for the changes you want to be made?

Yes. Our first step will be getting the completed clarification mails 
to you. (Note that the starter draft below has been superseded.)

Depending on your response, the group would either proceed to prepare 
and provide change proposals, or would consider what other actions 
the group may wish to take. This could potentially include filing 
formal objections with an appeal to the Director for expedited review 
prior to Last Call Working Draft.

We understand your concern about the timeline, but believe you also 
understand our concern about accessibility support in the HTML5 
specification. There is widespread concern at this time that 
accessibility support in the current version of the HTML5 draft going 
forward is inadequate, and we note W3C's commitment to ensuring 
support for accessibility in its specifications. We remain interested 
in working with you towards a resolution on that, and would prefer 
doing so as a team. Especially given the complexities of the HTML WG 
process, we feel that increased dialog may improve the chances for an 
expeditious resolution. Happy to discuss with you as needed.

- Judy and Janina

>/paulc
>
>Paul Cotton, Microsoft Canada
>17 Eleanor Drive, Ottawa, Ontario K2E 6A3
>Tel: (425) 705-9596 Fax: (425) 936-7329
>
>
>-----Original Message-----
>From: public-html-a11y-request@w3.org 
>[mailto:public-html-a11y-request@w3.org] On Behalf Of Judy Brewer
>Sent: Monday, April 25, 2011 11:55 AM
>To: HTML Accessibility Task Force
>Subject: [text] starter draft of clarification on alt validation, 
>for discussion
>
>DRAFT for discussion purposes only.... partly for approach, party 
>for content...
>
>[DRAFT]
>
>Dear All,
>
>With regard to the HTML Working Group Co-Chairs' decisions, as 
>described in the following email...
>
>http://lists.w3.org/Archives/Public/public-html/2011Apr/0451.html
>
>
>...which discussed the following information...
>
> >There is a basic disagreement in the group on the validity requirements
> >for alt.  The result was two issues, six change proposals, and a straw
> >poll for objections:
> >
> >http://www.w3.org/html/wg/tracker/issues/31
> >http://www.w3.org/html/wg/tracker/issues/80
> >http://lists.w3.org/Archives/Public/public-html/2010Jul/0050.html
> >http://www.w3.org/html/wg/wiki/ChangeProposals/ImgElement20090126
> >http://www.w3.org/html/wg/wiki/ChangeProposals/ImgElement20100706
> >http://www.w3.org/html/wg/wiki/ChangeProposals/ImgElement20100707
> >http://www.w3.org/html/wg/wiki/ChangeProposals/ImgElement20100510
> >http://www.w3.org/html/wg/wiki/ChangeProposals/ImgElement20100504
> >http://www.w3.org/2002/09/wbs/40318/issue-31-80-validation-objection-po
> >ll/results
>
>
>...and which arrived at the following six conclusions...
>
> >Therefore, the HTML Working Group hereby decides that:
> >
> >    * The presence of aria-labelledby does not make missing alt conforming.
> >    * The presence of role=presentation does not make missing alt 
> conforming.
> >    * The presence of <meta name=generator> makes missing alt conforming.
> >    * Use of private communications does not, in itself, make missing
> > alt conforming.
> >    * The presence of title makes missing alt conforming.
> >    * The presence of figcaption makes missing alt conforming.
>
>
>...and which furthermore proposed addressing these through 
>implementation of a combination of the following two Change Proposals...
>
> >The two Change Proposals closest to these results are those identified
> >as Requirement Set 1 and Requirement Set 4:
> >
> >     http://lists.w3.org/Archives/Public/public-html/2010Jul/0050.html
> >     http://www.w3.org/html/wg/wiki/ChangeProposals/ImgElement20100707
> >
> >These Change Proposals agree with each other and with the WG decision
> >on aria-labeldby, role=presentation and figcaption.
> >
> >On the generator mechanism and the title attribute, Requirement Set 1
> >aligns with the WG decision:
> >
> >     http://lists.w3.org/Archives/Public/public-html/2010Jul/0050.html
> >
> >On the email exception, Requirement Set 4 aligns with the WG decision:
> >
> >     http://www.w3.org/html/wg/wiki/ChangeProposals/ImgElement20100707
> >
> >Thus, overall, the WG adopts the Requirement Set 1 proposal with
> >regards to aria-labelledby, role=presentation, <meta name=generator>,
> >title and figcaption; but Requirement Set 4 with regards to the email
> >exception.
>
>
>...we note that the following information was not considered. The 
>respondents on the surveys mentioned above had not anticipated that 
>this information would be unknown to the Co-Chairs, and so have 
>described this information in some detail within this mail, and 
>presented test samples to illustrate failures associated with the 
>proposed approaches. These clarifications follow.
>
>
>On the Co-Chair's decision on aria-labelledby:
>
> >    * The presence of aria-labelledby does not make missing alt conforming.
>
>The purpose of alt is to provide alternative text on images, and to 
>allow a user agent to render text in place of the images when images 
>are turned off.
>
>As an example, applications such as Yahoo! mail render alt text for 
>images when web page content is embedded in a mail message. This 
>allows applications and browsers to only fetch images if a user 
>really needs them, improving download performance; and providing a 
>label to explain to the sighted user what is missing.
>
>aria-labelledby is used to reference a label that is already visible 
>on the page, similar to an image caption. Authors put these captions 
>or labels in order to assist the sighted user in providing context 
>about the user.
>
>Both the label and the alt text serve the same purpose when images 
>are turned off; and both provide a label. It does not seem 
>appropriate  to force the author to provide two labels for the same 
>image, and to have two labels rendered when images are turned of.
>Both will supply a label or "name" for the image in the accessibility API.
>
>Consequently, we request that the Co-Chairs consider allowing 
>aria-labelledby to be used to point to a label as a suitable 
>alternative to alt.
>
>
>On the Co-Chair's decision on role=presentation:
>
>  > * The presence of role=presentation does not make missing alt conforming.
>
>Alt having a value of "" tells the user and assistive technology 
>that the image is presentational. Yet, with alt="" an assistive technology
>(AT) must still filter out the image when it has no intrinsic value 
>other than to be decorative or be used as a spacer.
>
>Unlike alt="", role="presentation" has the added value of removing 
>the image from the accessibility API object tree, effectively 
>filtering out the image and improving assistive technology 
>performance. Furthermore, a role of presentation is to state the 
>intent of the author in a declarative fashion. For these reasons, 
>role="presentation" should be considered a suitable alternative to 
>requiring alt when it adds no meaningful information to an AT.
>
>As background, note that in most cases, browsers map browser content 
>to platform accessibility APIs, and an accessible object with a 
>standard API interface is created for each DOM object in a web page.
>These objects are referenced and communicated with by an AT to 
>process accessibility information about visible objects in the web page.
>
>
>On the Co-Chair's decision on the presence of title making missing 
>alt conforming:
>
>  > * The presence of title makes missing alt conforming.
>
>Title has a completely different function from alt in HTML.
>
>Title is used to generate a tooltip, and is invisible when images 
>are turned off. Alt does not generate a tooltip, and is visible when 
>images are turned off.
>
>If title is allowed as alternative text over alt it will break 
>applications such as Yahoo! mail; it will also break a commonly-used 
>feature, in less powerful mobile phones, where images are turned off 
>to improve performance.
>
>If title were to be used in place of alt then when images are turned 
>off in the browser, nothing meaningful will be shown in the browser.
>
>Furthermore, having title take precedence over alt will result in 
>tooltips being generated on decorative images and spacers, which 
>would do tremendous harm to the user experience.
>
>It should be noted that title is used as a last resort when other 
>measures cannot be employed to compute the label or "name" of an 
>object in the accessibility API mapping for browsers.
>
>Please note the following demonstrations of failures resulting from 
>the proposed approach:
>
>http://www.paciellogroup.com/blog/misc/HTML5/alt-tests/screenshots.html
>
>
>On the Co-Chair's decision on the presence of figcaption making 
>missing alt conforming:
>
>* The presence of figcaption makes missing alt conform
>
>[clarification pending]
>
>
>Please let us know if additional clarification is needed, and thank 
>you in advance for your re-consideration.
>
>Regards,
>
>....

--
Judy Brewer    +1.617.258.9741    http://www.w3.org/WAI
Director, Web Accessibility Initiative (WAI), World Wide Web Consortium (W3C)
MIT/CSAIL Building 32-G526
32 Vassar Street
Cambridge, MA,  02139,  USA  
Received on Saturday, 30 April 2011 02:39:34 GMT

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