{TAIL ~ A registration wall} may be positioned beside the entrance pulleys to register upper edges of {HEAD ~ the envelopes} 
{ TAIL ~ A registration wall } may be positioned beside the entrance pulleys to register upper edges of { HEAD ~ the envelopes }
TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD