Usability testing of XML vocabularies?

["Costello, Roger L." <costello@mitre.org>]

Hi Folks,

I just finished reading a book on Web Usability [1].

The book describes how to test the usability of a Web site: sit down
with a user and ask them to perform tasks on the site, ask them if they
understand the purpose of the site, ask them if they understand each
section on a page, and so forth.  By conducting such usability tests,
the tester can get a good idea of where things are not clear, and where
users stumble.

It occurred to me that when an XML vocabulary is created, or being
created, it would be useful to conduct usability testing to see if
users - developers - correctly understand the semantics of the
elements, the intended purpose of the XML vocabulary, the constraints
on and relationships between the elements, and so forth.

How do you conduct usability testing on XML vocabularies you develop?

How do the standards bodies - W3C, OASIS, ISO - conduct usability
testing on the XML vocabularies they produce? 

/Roger

[1] Don't Make Me Think! A Commonsense Guide to Web Usability by Steve
Krug