a) providing a controller operatively connected to {TAIL ~ each} of {HEAD ~ the independently driven nip rollers} 
a ) providing a controller operatively connected to { TAIL ~ each } of { HEAD ~ the independently driven nip rollers }
OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD