A production line has a plurality of {TAIL ~ working groups} in which {HEAD ~ work operations} are controlled by a sequential controller 
A production line has a plurality of { TAIL ~ working groups } in which { HEAD ~ work operations } are controlled by a sequential controller
OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL REL OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH