WS-Context model text

[Mark Little <Mark.Little@arjuna.com>]

As promised, here is the clarification text that should hopefully map to the 
UML diagram I sent round. There are a number of issues that the editors have 
come up with when writing this text, but rather than put into this text, we've 
factored them out. Once people have had a chance to digest the diagram and 
text, I'll send the issues the editors have come up with.

Mark.