There are several examples of "dual events" in CRM: - E8 Acquisition: transferred title from; transferred title to - E9 Move: moved from; moved to - E10 Transfer of Custody: custody surrendered by; custody received by - E15 Identifier Assignment: assigned, deassigned - E81 Transformation: transformed; resulted in - E80 Part Removal: removed & diminished; E79 Part Addition: added & augmented
I think that Part Removal and Part Addition should be merged. This will allow more consistent modeling of the following situations: - moving an object from one collection to another (similar to E8 and E10): removed=added=<object>, diminished=<old_collection>, augmented=<new_collection> - replacing a part of an object (similar to E81): removed=<old_part>, added=<new_part>, diminished=augmented=<object>
