Preferably, {HEAD ~ the system} includes a transaction interface associated with {TAIL ~ the control system} for carrying out a current transaction 
Preferably , { HEAD ~ the system } includes a transaction interface associated with { TAIL ~ the control system } for carrying out a current transaction
OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH