First, let me say that in general I find the MSM flags feature a good idea. Something similar (but of course much slower) can be achieved by deriving a number of statechart states from the same additional base class and then query with state_cast. I too have found this invaluable at times.

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But you'd have to refactor an equivalent MSM Machine too (you'd need to introduce the flag), right?

True, but adding one line to a few states is a lot less work than adding a composite, giving it a transition table and changing the transition table of the state machine.

No, in this particular scenario I'd leave all the existing transitions in place and just add the CDLoaded outer state. This is barely more work than adding the flag, right? Ultimately, what I'm getting at is that your justifying example in MsmSession_Handout.pdf could be better, because most Statechart users wouldn't write the code you're implying they would. MSM vs. Statechart aside, MSM users might be left with the question what flags are good for when they can achieve the same with an additional outer state. Again, flags are good, but the justifying example isn't. Regards, -- Andreas Huber When replying by private email, please remove the words spam and trap from the address shown in the header.