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What does "works" mean here? Re: 48-Hour Consensus Call: InstateLongdesc CP Update

From: Charles McCathie Nevile <chaals@yandex-team.ru>
Date: Sun, 23 Sep 2012 14:42:50 +0200
Cc: "David Singer" <singer@apple.com>, "HTML Accessibility Task Force" <public-html-a11y@w3.org>
To: "Gez Lemon" <g.lemon@webprofession.com>, "James Craig" <jcraig@apple.com>
Message-ID: <op.wk29lo2py3oazb@chaals.local>
Hi James,

(in my initial reply to your proposals I made a poorly-explained comment
about using the technique under 500% zoom plus high-contrast. This is in
part an attempt to provide the explanation I should have given at the
time).

On Sat, 22 Sep 2012 03:21:10 +0200, James Craig <jcraig@apple.com> wrote:
> On Sep 17, 2012, at 3:06 PM, Gez Lemon <g.lemon@webprofession.com> wrote:
>> On 17 September 2012 22:30, David Singer <singer@apple.com> wrote:
>>> On Sep 17, 2012, at 13:58 , Gez Lemon <g.lemon@webprofession.com>
>>>> I support the change proposal, as there is no other reliable method
>>>> that is supported today that does the same thing as longdesc.
>>>
>>> The trouble is, longdesc is neither widely supported nor reliable  
>>> today.  If it was, I suspect that we would not be having this  
>>> discussion.
>>
>> It is better supported and more reliable than no solution at all for
>> providing a long description for complex images.
>
> Here are six examples. Three of which work today. One which works in all  
> implementations, which is more than can be said of longdesc.
>
> http://cookiecrook.com/longdesc/

I presume the one you claim works today is
http://cookiecrook.com/longdesc/iframe/

As I understand this teachnique, (and from my own testing) it only works
for people who are browsing with images off, or using a screen reader.
While this describes a well-known accessibility scenario, if those are
indeed requirements the technique also fails in some very common
accessibility scenarios.

In particular, many people with visual disabilities who would benefit from
long descriptions do not turn images off. And thanks to the broad support
in modern systems for things like magnification and high contrast such
people are likely to have a setup that meets their needs better than
assuming a screenreader is somehow the answer to visual accessibility
problems.

I may well have misunderstood something important, or you may not yet have
explained it because you thought it was obvious. But if my understanding
is correct, then I think there are some serious problems with the iframe
solution proposed.

Because there is no "strong association" that software could rely on (as
most screenreaders do for longdesc), this effectively shifts the burden of
orienting the user from a handful of software developers - to all authors.
There is a reason why the proposed statement of principles for designing
HTML suggests that should be avoided. If your example doesn't work with
images turned on, I suggest it as evidence that this approach isn't likely
to be a great improvement on what we have today even given that we manage
to get faster adoption among users than would be possible for longdesc.

cheers

Chaals

-- 
Charles McCathie Nevile - Consultant (web standards) CTO Office, Yandex
         chaals@yandex-team.ru         Find more at http://yandex.com
Received on Sunday, 23 September 2012 12:43:24 GMT

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