RE: programmatically determined and AT

 
At 19:30 25/01/2006, Gregg Vanderheiden wrote:
<blockquote>
I'm trying to work out the implications here. Would this have the effect of
making only markup languages conform (declarative) but not script
(imperative)?
</blockquote>

Christophe Strobbe wrote:
To my understanding, scripts would not conform, so this will never be
accepted at a level higher then L3.
Also, I don't know what this does for PDF and Flash (to name just two
examples).

GV:  I'm not sure I follow.  Are you saying that "programmatically
determined could only be at level 3?   Or that scripting techniques could
only be used at level 3?  Or something else?    

If Scripting is in the baseline - it should be ok to use at any level.




Gregg:
<blockquote>
Also, declarative doesn't mean that AT can actually access it - even if it
is static.
</blockquote>

I pointed out the distinction between declarative and imperative under the
assumption that declarative code would make changes of context (or any other
events) much easier to determine programmatically. As far as I know, we
can't make it easier than that. For example, for changes of context,
imperative code specifies how certain events should be handled, but
declarative code specifies what should happen and the "how" could be left to
the user agent. User agents may then (hopefully) handle certain events in a
way that is less confusing than what we now get with JavaScript.
In markup languages, VoiceXML and XForms are the only technologies that I
know of that use declarative events and handlers.


GV: Don't follow what you are saying.  Not having script is easier than with
it.  But if AT can handle it - then it shouldn't be barred.  




Gregg:
<blockquote>
Our problem was that we can't define AT specifically without naming specific
AT (since there is no AT interop standard). And this doesn't seem to address
that.
</blockquote>

No, the suggested approach is different: instead of naming AT, name specific
types of technology features that they should be able to determine
programmatically.

GV:  This gets back into theoretical accessibility.  It isn't whether a
person with a disability can access the content.  It is whether
theoretically they should be able to if the AT existed.   This is something
we have talked about.  But so far - we have been thinking that baselines
would be selected based on what actually did work. 




Gregg:
<blockquote>
It is a very interesting thought though. Just not sure if it addresses the
key problem.
</blockquote>

It does not make a difference to 3.1.1 (normally).
It makes a difference for content that is inserted, deleted or modified as a
result of events, so it affects 1.3.1, 1.3.2, 1.3.3, 1.3.5, 2.4.1, 3.1.2.
It is very important for components or controls that are very frequently
manipulated by scripts, especially form controls, so the distinction between
declarative and imperative has a high impact on 4.1.2, 4.1.3, 4.1.4, 4.1.5.
(References are to the editor's draft of 17 January, at
http://www.w3.org/WAI/GL/WCAG20/WD-WCAG20-20060117/guidelines.html).



GV:  Yes PD does affect a lot of the success criteria, either way.  Thanks
for the ideas.   



Regards,

Christophe

-----Original Message-----
From: w3c-wai-gl-request@w3.org [mailto:w3c-wai-gl-request@w3.org] On Behalf
Of Christophe Strobbe
Sent: Wednesday, January 25, 2006 11:54 AM
To: w3c-wai-gl@w3.org
Subject: programmatically determined and AT


Hi,

We still don't have a satisfactory solution for "programmatically
determined" and AT. "Theoretically programmatically determined because
defined in formal specifications" is not sufficient because there may be
features in specifications that no AT has implemented yet. On the other hand
we can't just say "AT" without saying which AT.

What we have not discussed so far is the distinction between
- programmatically determined in a declarative manner, and
- programmatically determined in an imperative manner.

This distinction is based on the distinction between declarative and
imperative (programming) languages:
- imperative languages basically describe sequences of operations,
- declarative languages basically describe what is computer.[1]

We deleted the old SC 3.2 L1 SC1 ("Any change of context is implemented in a
manner that can be programmatically determined.") on the basis that any
change of context that cannot be programmatically determined will simply
never happen because a UA cannot detect that it is supposed to happen. The
SC would not have been removed if it had read: "Any change of context is
implemented in a declarative way". That would have ruled out changes of
context caused by JavaScript (which is an imperative language), which many
will find to strong at level 1.

The distinction between declarative and imperative is interesting because it
is what gave rise to the XML Events spec
(http://www.w3.org/TR/2003/REC-xml-events-20031014/) and the use of XML
Events in XForms (http://www.w3.org/TR/2003/REC-xforms-20031014/). Many
things that HTML form authors do with JavaScript (imperative code) can now
be done with XML Events (required fields, hints, context-sensitive help,
adding fields based on the value of other fields, etc). This has the
advantage that events (and therefore changes of context) are "statically
analyzable": there's no need for AUs to actually run any code (JavaScript)
to find out what kinds of events might happen.
Can this be a way out of this catch-22?


[1] More on this subject at
http://www.csc.liv.ac.uk/~frans/OldLectures/2CS24/declarative.html and
http://en.wikipedia.org/wiki/Declarative_programming.

Regards,

Christophe Strobbe

-----End Original Message-----


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Christophe Strobbe
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Received on Thursday, 26 January 2006 04:18:39 UTC