{TAIL ~ The RA} provides a subsystem with a mechanism for sending read and write request to {HEAD ~ the DA} of another subsystem 
{ TAIL ~ The RA } provides a subsystem with a mechanism for sending read and write request to { HEAD ~ the DA } of another subsystem
TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH