A system 9, wherein the plurality of pieces of mail includes at least one of {TAIL ~ a plurality} of letters and a plurality of {HEAD ~ flats} 
A system 9 , wherein the plurality of pieces of mail includes at least one of { TAIL ~ a plurality } of letters and a plurality of { HEAD ~ flats }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD