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