Agreed approach to issue 4.2

[peter_niblett@uk.ibm.com]

Issue: The Topic Set document is not completely specified, and there is no normative specification for transforming topic entries from a topic space document into the Topic Set document

Proposal:
1. Additional text to emphasise the role of the Topic Set
-Add precis
-Add example
2. Normatively specify the structure of a Topic Set document and the interpretation of the XPATH-like Expressions, not the process that the NP uses to build it (so no need to include XSLT)
3. Rename TopicSpace to TopicNamespace
4. New minOccurs=0/maxOccurs=1 ResourceProperty on NP to retrieve the TopicSet as a document in addition to the existing Topics RP.
5. Allow additional metadata to be embedded in the Topic Set document
-NP can elect to insert this metadata if it chooses
-Full XPATH dialect would allow selection against this metadata.