The same system is simulated with (left) or without (right) a regulating system. Both systems give the same output but the first one limits internal congestions.
Time variant : crossings C1 and C2 are allocated in time-intervals. This is modeled by variable delays.
Event-variant : parts are processed by M1 and M2 in a cyclic way M1,M2,M2,M1,M2,M2,M1... (Demux/Mux)