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