{HEAD ~ The ledger} may be kept at a central control system, at a local network for localized transaction tracking, or at {TAIL ~ a remote network} for more regional or national transaction tracking 
{ HEAD ~ The ledger } may be kept at a central control system , at a local network for localized transaction tracking , or at { TAIL ~ a remote network } for more regional or national transaction tracking
HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH REL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH