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