[osis-core] osis_0108.2 use of "xs:redefine.

[Todd Tillinghast]

I sent out a slight modification to OSIS_0108 earlier today.  The
difference is that it validates with the IBM valuator and that it
defines basic versions of OSISID, OSISIDREF, OSISIDREFS, and
ReferenceType which are then redefined with versions that validate the
references.

The down side is that whatever is redefined must be based on the Complex
or Simple Type of the same name in the OSISCore_xxxx.xsd file.  This
removes some flexibility but seems acceptable.

I did not hear from anyone regarding this change, so I assume everyone
is happy with the idea.  (It is hard to argue with when it validates and
the other one does not.)

Objections to using xs:redefine?

Todd