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

From: Steve Faulkner <faulkner.steve@gmail.com>
Date: Tue, 26 Apr 2011 12:05:06 +0100
Message-ID: <BANLkTi=hfLgLrmxJUW-A8LEQu24uHcmFPA@mail.gmail.com>
To: Judy Brewer <jbrewer@w3.org>, Richard Schwerdtfeger <schwer@us.ibm.com>
Cc: HTML Accessibility Task Force <public-html-a11y@w3.org>
Hi Judy,

In regards to the alt/title decision I would like to make these further
points:

1. figure/figcaption provides the opportunity to convey a clear semantic
differention between a caption and a text alternative. Use of the title
attribute does not. title maps to the accessible name property (in cases
where no other accessible label is provided) in accessibility APIs while
<figcaption> can be mapped to a caption role in accessibility APIs.

The IAccessible2<http://accessibility.linuxfoundation.org/a11yspecs/ia2/docs/html/>and
AT-SPI<http://people.gnome.org/%7Ebillh/at-spi-idl/html/namespaceAccessibility.html#a216>accessibility
API's have caption roles:

"ROLE_CAPTION The object contains descriptive information, usually textual,
about another user interface element such as a table, chart, or image."

I have also suggested that a caption role be added to ARIA next. (
http://lists.w3.org/Archives/Public/wai-xtech/2011Apr/0007.html)

2. The accessible support story for the title attribute has always been poor
and there is no indication that this will change.
NO graphical browser provides device independent support for display of
tooltips and the support has not improved over the last 6 years since I
detailed issues with the title attribute in 2005 [4].
So far no browser vendor representatives have given a positive response to
my query [1] about whether this will change, but 2 stated there are no plans
to [2].
Support for the display of title attribute content has decreased markedly
over the last few years, none (to my knowledge) of the mobile or touch
screen browsers developed provide access to it. I have recently published
Information and guidance based on current known issues [3].



[1]http://lists.w3.org/Archives/Public/public-html/2011Apr/0468.html
[2]
http://lists.w3.org/Archives/Public/public-html/2011Apr/0490.html
http://lists.w3.org/Archives/Public/public-html/2011Apr/0507.html
[3]
http://www.paciellogroup.com/blog/2010/11/using-the-html-title-attribute/
[4] http://www.paciellogroup.com/resources/articles/WE05/

regards
Stevef


On 25 April 2011 16:55, Judy Brewer <jbrewer@w3.org> wrote:

> 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-poll/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,
>
> ....
>
>
>
Received on Tuesday, 26 April 2011 11:05:54 GMT

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