CWM12 — Identify precise CWM definition to which interchange doc. conforms

Provide in the body of a CWM interchange document, a means for
identifying the precise CWM definition to which the interchange document
conforms. Something similar to the way the XML documents identify the URI
of the XML definition they conform to would do nicely. Such a mechanism in
effect creates a name space within which the contents of the CWM interchange
document can be evaluated. Useful side effects of having such a namespace
include: (1) the definition of CWM extension packages without the present
need that they be accompanied by the CWM definition itself, (2) a framework
in which Universally Unique Identifiers (UUIDs) can be defined for each CWM
object. Several requests for CWM UUIDs have already been received
informally.