{TAIL ~ A system} for exchanging data between a portable payment terminal and a stationary base terminal in {HEAD ~ communication} with a payment center 
{ TAIL ~ A system } for exchanging data between a portable payment terminal and a stationary base terminal in { HEAD ~ communication } with a payment center
TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH