An integer number is assigned to each transition. Whenever there is a conflict that cannot be solved with the ITF and OTF scheme, the priority numbers are used. The priority number is placed between square brackets after the TRANSITION descriptor. By default, each transition has a priority number of 0.
For example, two transitions are defined in Table 4.7. The model is initialized in state A. When event e occurs, both transitions are enabled and hence there is a conflict that cannot be solved with the ITF and OTF convention (because they have the same source state ). In this case, their priority numbers are used to solve the conflict. Since the second transition has a smaller priority number, it has higher priority and is thus fired.