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