Multiple headboxes could be controlled, such as when {TAIL ~ different headboxes} are used to produce {HEAD ~ different layers} of a multi layer sheet 
Multiple headboxes could be controlled , such as when { TAIL ~ different headboxes } are used to produce { HEAD ~ different layers } of a multi layer sheet
OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH