I got an interesting idea while thinking about subtrees and specifications.  As you know we complied
up until recently strictly with the X.500 administrative model with respect to subtreeSpecifications.  The
changes we added to handle refinements which were filters broke away from X.500 in many ways. 

I was just thinking that it may be possible to use an extendedSubtreeSpecification attribute which
extends a subtreeSpecification.  However the only problem with this is the fact that the attributeType
subtyping another cannot switch the SYNTAX of the AT.  This is what I always thought but perhaps
I am wrong (I hope) but if I am wrong I think we can leverage AT extension while remaining compliant. 

Basically we can allow our subentry objectClasses to include extendedSubtreeSpecifications instead
of just the usual subtreeSpecification.