The concern with fragment identifiers was that certain media types developed
before the XLink spec (I remember SVG being mentioned), might not confirm to
the later linking spec. If all it takes to conform to the linking spec is
to be valid XML, than by definition all +xml media types do so, so there's
no problem with the current draft. If something extra is required, than the
SHOULD language is appropriate since some media types may not do so, so
there's still no problem with the current draft.
After thinking about this some more, I realized that it was fragment
identifiers alone that I was concerned about. It's too bad XPointer
couldn't be ready in time for this draft to reference normatively, but I
accept your explanation as resolving my issue.
Thanks for the clarification.
MB