RE: BIG ISSUE -- re Delivery Units

> Hi Bruce

Thank you Gregg for your patient efforts with remedial vocabulary lessons.

> Here is the DI group definition of perceivable unit

I have been referencing the DI terms from the WCAG2 glossary.  That hasn't helped much.

> You have it at the wrong end of the chain.

Okay, so sometimes (e.g., a PDF file) a Delivery Unit contains multiple Perceivable Units (e.g., pages), other times (e.g., a web page with images) a Perceivable Unit contains multiple Delivery Units.  Are you satisfied that Web Unit avoids this conundrum?  How about my example of a frame based web "page"?  Each frame is a Web Unit (so each can have a title), but the whole bundle (web quote page unquote) is also a Web Unit?

The term content has similar issues.  Sometimes content is just part of a web page, content refers to a whole page or web application, sometimes content refers to a collection of pages or a whole site.

By the way, is a Perceivable Unit only that which fits into a widow (without scrolling) at any given time?  Again, I am hoping such a question is moot, at least with regard to WCAG 2.0.