Broadcast communication:

Assume S2 and T2 are active and have not been entered in the same step (thus transition Q2 to P2 is not enabled). In case the environment provides event G both transitions from S2 to S1 and from T2 to T1 are taken. So, multiple parallel states can react simultaneously to the same events, i.e. events are broadcasted no matter whether they are generated internally, i.e. by the system itself, or by the environment.