From Vectorworks Developer
.VectorScript|VectorScript ..VS:Function Reference|Function Reference ..VS:Function_Reference_Appendix|Appendix
DescriptionProcedure NameUndoEvent names the undo event that is currently being built by VectorScript execution. Parameter eventName is the name of the undo event.
def vs.NameUndoEvent(eventName): return None
eventName STRING Name of undo event.