Types of units (was: RE: 2.4.2 Issues)

Hi everyone,

After the Dublin meeting I created a statechart to get my head around the
different types of units (see attachment). This is the way I understood it
then, but I might be wrong. 

<longdesc>
A unit starts its life as the result of the Authoring proces. The unit is
then in a state called Authored unit. Server-side adaptations may transform
authored units into new authored units. Only when it is served does an
Authored unit become a Delivery unit. The delivery unit is what leaves the
author-controlled environment and is served to the user-controlled
environment. The user can now initiate additional adaptations to transform
the delivery unit into another type of delivery unit (for example by adding
acronym descriptions based on a user-controlled dictionary or even more
exotic methods). Finally, the delivery unit is rendered by the user agent
unto the perveived unit. The lifecycle of the unit ends with the perception
of the unit. 
</longdesc>

In other words: the transformation of the delivery unit to the perceived
unit is entirely outside the control of the author. The user can actively
choose to transform the delivery unit, for example by invoking some third
party tool to enhance the delivery units. The user agent renders the
delivery unit which makes it a perceivable unit. For that reason, I don't
think 'perceivable unit' is a useful term for WCAG because it's outside the
author's control.

Yvette


> -----Original Message-----
> From: public-wcag-teamb-request@w3.org 
> [mailto:public-wcag-teamb-request@w3.org] On Behalf Of John M Slatin
> Sent: donderdag 2 februari 2006 19:06
> To: Loretta Guarino Reid; public-wcag-teamb@w3.org
> Subject: RE: 2.4.2 Issues
> 
> 
> The problem with "perceivable unit" (as I understand it) is 
> that authors can't control what happens when a single 
> delivery unit is rendered as multiple perceivable units, so 
> ther emight not be a way to satisfy the SC if we used David's 
> wording  .
> 
> I'm not completely certain that I understand "perceivable unit"
> properly. The term comes from the Device Independence WG's Glossary.
> Could someone check it and se if we can determine whether 
> perceivable unit is or isn't under authorial contrl? (We may 
> also need to check with someone from DI WG to be sure on this one.)
> 
> Thanks,
> John
> 
> 
> 
> "Good design is accessible design." 
> John Slatin, Ph.D.
> Director, Accessibility Institute
> University of Texas at Austin
> FAC 248C
> 1 University Station G9600
> Austin, TX 78712
> ph 512-495-4288, f 512-495-4524
> email jslatin@mail.utexas.edu
> web http://www.utexas.edu/research/accessibility/
> 
> 
>  
> 
> 
> -----Original Message-----
> From: public-wcag-teamb-request@w3.org
> [mailto:public-wcag-teamb-request@w3.org] On Behalf Of 
> Loretta Guarino Reid
> Sent: Thursday, February 02, 2006 8:50 am
> To: public-wcag-teamb@w3.org
> Subject: 2.4.2 Issues
> 
> 
> 1. Issue 1825:
> http://trace.wisc.edu/bugzilla_wcag/show_bug.cgi?id=1825
> 
> Recommendation: Close this issue saying that 2.4.7 haw been 
> changed to remove "page or other".
> 
> 2. Issue 1741
> http://trace.wisc.edu/bugzilla_wcag/show_bug.cgi?id=1741
> 
> Recommendation: adopt David Macdonald's proposal, which 
> clarifies that the SC only applies at the delivery unit level.
> 
> <current>
> 2.4.2 More than one way is available to locate content within 
> a set of delivery units where content is not the result of, 
> or a step in, a process or task. </current>
> 
> <proposed>
> 2.4.2 More than one way is available to locate each delivery 
> unit within a set of delivery units where the content of the 
> delivery unit is not the result of, or a step in, a process or task.
> </proposed>
> 
> More of the issue might be addressed if we used "perceivable unit"
> instead of "delivery unit". Would there be problems if we change this
> to:
> 
> <proposed>
> 2.4.2 More than one way is available to locate each 
> perceivable unit within a set of perceivable units where the 
> content of the perceivable unit is not the result of, or a 
> step in, a process or task.
> </proposed>
> 
>