{HEAD ~ Registration} of envelopes is established at the entrance and is maintained by {TAIL ~ a horizontal flat registration plate} located about half of the travel distance between the entrance and exit pulleys 
is maintained by
{ HEAD ~ Registration } of envelopes is established at the entrance and is maintained by { TAIL ~ a horizontal flat registration plate } located about half of the travel distance between the entrance and exit pulleys
HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH REL REL REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH