Section 8 - Simple editorial comments

932-939: Entire section is verbose and distracting. Not sure how to fix.

962-963 appears to be redefining URL again.

964: Delete "As a matter of fact"

973-978: Remove explicit XML references
"Within any problem domain, the intra-model relationships can be expressed either by using containment or by references. The choice changes the semantics of the model expression as well as of accessing the elements within the model.
If the model is expressed through containment, then we use the term Extent to refer to the tree of children contained within that element. Only elements that have an HREF have an extent; objects without an HREF are included within the extent of one or more referenceable elements which we term its Ancestors.

Section 8.4 (992-997) appears to be XML encoding rules. If they are meant to be general model rules, please re-write. If they are XML-specific rules, suggest moving to XML section of Common Encodings.