{TAIL ~ A jacket} is separated from the stack and pushed forward onto {HEAD ~ an insert unit} on a slightly lower level 
{ TAIL ~ A jacket } is separated from the stack and pushed forward onto { HEAD ~ an insert unit } on a slightly lower level
TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH