FW: BIG ISSUE -- re Delivery Units

I believe the opacity of the term “delivery unit” is actually a bigger problem than the fact that the definition from Glossary of Terms for Device Independence is not correct for what is meant.  Web Unit has this same defect.

The new definition is very good, and including “e.g. page” is extremely helpful.  I suspect it might be a productive exercise to articulate exactly why the term “page” is not satisfactory.

Most of the SC use the term “content” which is elegant.  Some of the SC could benefit from a similar treatment.  For example:

4.1.1: Content can be parsed unambiguously and the relationships in the resulting data structure are also unambiguous.

There definitely are SC where this approach is problematic:

2.4.4: Content has titles.

The glossary currently uses delivery unit in the definition of content.  Can this be avoided?  I don’t thing the current definition for content makes it clear that content can be single files (like PDF or Word) and web applications.

The concept of scope, and that conformance claims are for all scoped content, might help clarify what is meant by “content”.

Other terms resulting from some brainstorming with a colleague:  browser page, document, web document, document or file, web document or web application.


-----Original Message-----
From:	w3c-wai-gl-request@w3.org on behalf of Gregg Vanderheiden
Sent:	Wed 2/8/2006 4:23 PM
To:	w3c-wai-gl@w3.org
Cc:	
Subject:	BIG ISSUE -- re Delivery Units

Currently we have a number of success criteria that talk about delivery units.    However, the delivery unit is anything you can get with an HTTP request. 

(All of the sc that the term delivery unit is used in our guidelines are listed at the bottom of this email.)

So a page with all of its images is a D U.  But each image by itself is also a D U.  

The problem is 

1.	the images don't pass our guidelines
2.	if you make any kind of claim for your site (or any URI pattern) it would include the URI’s for the images etc (unless you stored the images off in some remote location)

This is not what we intend.    After looking at this for awhile Ben and John and I are suggesting that perhaps we focus on the delivery unit you get from a user request and not the subsequent delivery units that are fetched as part of it.   To do this we would need to define a new entity. 

John, Ben and I have discussed and examined this and are proposing a new term “Web Unit” that would replace all occurrences of Delivery Unit in the guidelines and related documents.

Take a look.  Think hard.  And then send your comments.  

Web Unit (e.g. Page)

    A collection of information, consisting of one or more resources, intended to be rendered together, and identified by a single Uniform Resource Identifier (URLs etc.).     

NOTE:    This term was adapted from the definition of web page in Device Independent group and Web Characterization Terminology & Definitions Sheet except concept of simultaneity was removed to allow the term to cover interactive multimedia content.

Example 1:  A web page including all embedded images and media. 

Example 2:  An interactive movie like shopping environment where the user navigates about and activates products to have them demonstrated, and moves them to cart to buy them. 

Here are all the occurrences of Delivery Unit. 

2.2.2  [P/D] Content does not blink <http://www.w3.org/WAI/GL/WCAG20/appendixA.html#blinksdef>  for more than 3 seconds, or a method is available to stop any blinking content in the delivery unit <http://www.w3.org/WAI/GL/WCAG20/appendixA.html#deliveryunitdef> . [How <http://www.w3.org/WAI/GL/WCAG20/WD-UNDERSTANDING-WCAG20-20060117/Overview.html#time-limits-blink>  to meet 2.2.2] 

2.4.2 [P] More than one way is available to locate content within a set of delivery <http://www.w3.org/WAI/GL/WCAG20/appendixA.html#deliveryunitdef>  units where content is not the result of, or a step in, a process or task. [How <http://www.w3.org/WAI/GL/WCAG20/WD-UNDERSTANDING-WCAG20-20060117/Overview.html#navigation-mechanisms-mult-loc>  to meet 2.4.2] 

2.4.3 [P] Blocks of content that are repeated on multiple perceivable units <http://www.w3.org/WAI/GL/WCAG20/appendixA.html#perceivableunitdef>  [NEEDS TO BE CHANGED TO DU]  are implemented so that they can be bypassed. [How <http://www.w3.org/WAI/GL/WCAG20/WD-UNDERSTANDING-WCAG20-20060117/Overview.html#navigation-mechanisms-skip>  to meet 2.4.3] 

2.4.4 [P] Delivery <http://www.w3.org/WAI/GL/WCAG20/appendixA.html#deliveryunitdef>  units have titles. [How <http://www.w3.org/WAI/GL/WCAG20/WD-UNDERSTANDING-WCAG20-20060117/Overview.html#navigation-mechanisms-title>  to meet 2.4.4] 

2.4.5 [P] Each programmatic reference <http://www.w3.org/WAI/GL/WCAG20/appendixA.html#programmatic-referencedef>  to another delivery <http://www.w3.org/WAI/GL/WCAG20/appendixA.html#deliveryunitdef>  unit or to another location in the same delivery unit, is associated with text describing the destination. [How <http://www.w3.org/WAI/GL/WCAG20/WD-UNDERSTANDING-WCAG20-20060117/Overview.html#navigation-mechanisms-refs>  to meet 2.4.5] 

2.4.7 [P] When a delivery <http://www.w3.org/WAI/GL/WCAG20/appendixA.html#deliveryunitdef>  unit is navigated sequentially, elements receive focus in an order that follows relationships and sequences in the content. [How <http://www.w3.org/WAI/GL/WCAG20/WD-UNDERSTANDING-WCAG20-20060117/Overview.html#navigation-mechanisms-focus>  to meet 2.4.7] 

2.4.8 [P] Information about the user's location within a set of delivery <http://www.w3.org/WAI/GL/WCAG20/appendixA.html#deliveryunitdef>  units is available. [How <http://www.w3.org/WAI/GL/WCAG20/WD-UNDERSTANDING-WCAG20-20060117/Overview.html#navigation-mechanisms-location>  to meet 2.4.8] 

3.1.1 [P] The primary natural <http://www.w3.org/WAI/GL/WCAG20/appendixA.html#natural-langdef>  language or languages of the delivery unit can be programmatically determined <http://www.w3.org/WAI/GL/WCAG20/appendixA.html#programmaticallydetermineddef> . [How <http://www.w3.org/WAI/GL/WCAG20/WD-UNDERSTANDING-WCAG20-20060117/Overview.html#meaning-doc-lang-id>  to meet 3.1.1]

3.2.3 [P] Navigational mechanisms that are repeated on multiple delivery <http://www.w3.org/WAI/GL/WCAG20/appendixA.html#deliveryunitdef>  units within a set of delivery units occur in the same <http://www.w3.org/WAI/GL/WCAG20/appendixA.html#samerelorderdef>  relative order each time they are repeated unless a change is initiated by the user. [How <http://www.w3.org/WAI/GL/WCAG20/WD-UNDERSTANDING-WCAG20-20060117/Overview.html#consistent-behavior-consistent-locations>  to meet 3.2.3] 

3.2.4 [P] Components that have the same functionality <http://www.w3.org/WAI/GL/WCAG20/appendixA.html#samefunctionalitydef>  in multiple delivery <http://www.w3.org/WAI/GL/WCAG20/appendixA.html#deliveryunitdef>  units within a set of delivery units are identified consistently. [How <http://www.w3.org/WAI/GL/WCAG20/WD-UNDERSTANDING-WCAG20-20060117/Overview.html#consistent-behavior-consistent-functionality>  to meet 3.2.4] 

4.1.1 [P/D] Delivery <http://www.w3.org/WAI/GL/WCAG20/appendixA.html#deliveryunitdef>  units can be parsed <http://www.w3.org/WAI/GL/WCAG20/appendixA.html#parsed-unambigdef>  unambiguously and the relationships in the resulting data structure are also unambiguous. [How <http://www.w3.org/WAI/GL/WCAG20/WD-UNDERSTANDING-WCAG20-20060117/Overview.html#ensure-compat-parses>  to meet 4.1.1] <http://trace.wisc.edu/bugzilla_wcag/issuereports/navigation-mechanisms_issues.php>