I think we need another thread to discuss the heap. Back to the high-water mark ... isn't it just the largest xmi id in the serialized CAS? Its relationship to the CAS heap is a matter of implementation but presumably we can have a design that says any new FSs must be given an xmi id above the high-water mark when serialized back from a service. We already have the requirement that ids must be preserved for the merging of parallel replies.
Burn.
