Behavior of the safe state machine option

The safe state-machine detects for states that aren't specifically defined, and send the SM back to reset(I beleieve). So if you have a binary encoded state-machine with 4 bits, and and your SM has 13 states, then it looks for those 3 extra states. What your outputs do is unkown(what would be considered safe?). If you need to control those, then you need to create your state-machines so there are no unencoded states, and define the outputs for each one.

I've twice done a fuller write-up on this topic, and then deleted it because it was probably more than you were asking for. But if you want to give more information on why you think your SM will go to an illegal state, and what type of result will it have, I might be able to give more info.