W3C home > Mailing lists > Public > public-html@w3.org > March 2011

Re: example spec text for longdesc

From: Jonas Sicking <jonas@sicking.cc>
Date: Fri, 25 Mar 2011 19:34:27 -0700
Message-ID: <AANLkTik73rP5W9m5MjRq_zVEJi0XS2bHbdmDEK6gpAQm@mail.gmail.com>
To: Laura Carlson <laura.lee.carlson@gmail.com>
Cc: Henri Sivonen <hsivonen@iki.fi>, HTMLWG WG <public-html@w3.org>
On Fri, Mar 25, 2011 at 6:57 PM, Laura Carlson
<laura.lee.carlson@gmail.com> wrote:
>> First of all it has always surprised me that the list of use cases
>> only list discusses adding accessibility information to images. Is
>> there a reason things like tables, SVG (and portions thereof), figures
>> and forms are left out?
> Do you mean that tables, SVG (and portions thereof), figures and forms
> are left out as they do not have mechanisms for providing a long
> descriptions?

I mean that all the discussions revolve around adding long
descriptions to images, rather than long descriptions on things that
require long descriptions.

> Would it be possible to make longdesc a global attribute? What would
> be the pros and cons?

This is software, anything is possible. If it's a good idea is a
separate question ;-)

>> Also, ease of use seems to be missing from that page. This isn't
>> really a use case but rather a requirement.
> Longdesc is a link so it is simple in that regard. Ease of use and
> simplicity are pretty evident in the formal use case scenarios. For
> instance:
> http://www.d.umn.edu/~lcarlson/research/ld.html#us-01
> http://www.d.umn.edu/~lcarlson/research/ld.html#us-02
> http://www.d.umn.edu/~lcarlson/research/ld.html#us-07
> http://www.d.umn.edu/~lcarlson/research/ld.html#us-08

And yet data shows that the vast majority of people get it wrong.


Do you have data showing otherwise?

>> However since the page
>> seems to be lacking a section for requirements maybe it would be ok to
>> list under use cases.
>> Would it be ok for me to go add these requirements to the wiki?
> Requirements are linked:
> http://www.w3.org/html/wg/wiki/ChangeProposals/InstateLongdesc#Requirements
> But I can flesh that out and add ease of use, etc.

Would be great if you could. Also please add the use cases of long
descriptions on things other than images.

>> Once you include these use cases and requirements it seems much less
>> that longdesc is a proper solution.
>> It's only available on <img>ages
>> (this missing all other ways even for including images such as
>> <canvas> and <object>).
> Yes. Images are what we have been talking about.
>> It isn't very user friendly. Lots of people
>> seem to misunderstand it to include the actual describing text rather
>> than a link to it.
> That's where better conformance tool and authoring tool checking along
> with more implementation would come in.

A terrifyingly small percentage of the pages on the web pass a
validator. The far vast majority of pages doesn't even nest their tags
correctly. The sad truth is that while we can do what you suggest,
it's not going to have a big effect because people simply doesn't
consult validators to a large degree.

So far I have seen no reason to believe that longdesc is going to be
used in a much better way the next 10 years than it has the past 10
years. If that's the case then we really aren't helping anyone. I'd
like to actually make the web better.

>> Not only that, but since it is url based, rather
>> than id based, it encourages people to put the description in an
>> external resource, which more often than not is not what you want to
>> do.
> Being an external resource is very important in many situations. For
> examples visit:
> Describing a Logo
> http://www.d.umn.edu/~lcarlson/research/ld.html#uc-01
> Describing an Email Banner
> http://www.d.umn.edu/~lcarlson/research/ld.html#uc-07
> Describing Illustrations
> http://www.d.umn.edu/~lcarlson/research/ld.html#uc-08
> Facilitating etext Image Descriptions Describing etext Images
> http://www.d.umn.edu/~lcarlson/research/ld.html#uc-09a

Indeed. I'm not saying that the use case doesn't exist. I'm saying
that it's not the majority case. We should optimize for the majority
case while making the minority case possible.

>> It turns out that ARIA already have a attribute that almost fits the
>> bill, and this is aria-describedby. As is pointed out on the wiki
>> page, the problem is that the ARIA specification only allows exposing
>> text content to the user, rather than arbitrary content, such as
>> links.
>> This problem can be fixed though by changing the ARIA specification.
>> By changing ARIA to say that aria-describedby can point to arbitrary
>> content, rather than just refer to the textual contents of it, we
>> solve multiple problems in one go.
>> This would first of all allow aria-describedby to solve all the use
>> cases in the wiki, as well as the ones pointed out in this message. It
>> also seems to fulfill the ease of use requirement better as people so
>> far seems to put an id in aria-describedby rather than the actual
>> text.
> aria-describedat has been discussed. There are quite a few reasons
> that it does not seem workable.
> http://www.w3.org/html/wg/wiki/ChangeProposals/InstateLongdesc#aria-describedat

First off I'm not proposing aria-describedat. I'm suggesting fixing a
problem in aria-describedby.

Second, I don't see anything in that link that says that
aria-describedat wouldn't work, mostly it seems to be arguing that
ARIA in general isn't good since it's not "Native HTML". However I
don't understand that argument now that HTML explicitly refers to

Anyhow, I still haven't heard any arguments against fixing
aria-describedby. Nor if fixing it is indeed needed. Can you, or
anyone else, point to where in the ARIA spec it actually says that
aria-describedby actually only exposes the textual contents of the
items it links to? Rather than exposing their full semantic structure.

> Sean Hayes just wrote up  "Configuring Internet Explorer to Handle
> Longdesc" It adds a context menu entry to extract the longdesc
> attribute value and have the page navigate to its content.
> http://blogs.msdn.com/b/accessibility/archive/2011/03/25/configuring-internet-explorer-to-handle-longdesc.aspx
> Jonas, is something like that doable natively in FireFox?

This is software, anything is possible. If it's a good idea is a
separate question ;-)

Anyhow: https://addons.mozilla.org/en-us/firefox/addon/longdesc/

/ Jonas
Received on Saturday, 26 March 2011 02:35:30 UTC

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