it is like what happens with the japanese railway system: the on time arrival of trains is not granted by forcing a check on each single train on the run. instead, it is the result of careful synchronization of the entry and departure of all the trains from/to each railway station. each train is considered with reference to the train running before and the one to follow. that is to say that the sequence can be effectively managed only by synchronizing the entire system and verifying the consistency among the drawings release plan, the supply plan and the production plan.