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