Is it necessary for a uml state machine to have a shallow history?

Question

Our supervisor said it is necessary for a composite state to have a shallow history..otherwise your tool that you are building does not make sense? Is this correct? The tool is an undergraduate project that allows a subset of class and state machine diagrams to be built..you can see screenshot on cyrusuml.com

Answer 1

It depends on the context, if the state machine needs to roll-back for any reason then the answer is yes. A example would be Parser for an LALR (Look-Ahead/Left to Right) Grammar were it is essential. However if there are is no need for roll-back then the answer would be no.

In this case since you are modeling state machines you need to be able to handle both kinds, those with and without roll-back; other wise as he says your tool is useless.