In addition, a third subsystem and fourth subsystem have {HEAD ~ S copies} of {TAIL ~ the data line} 
In addition , a third subsystem and fourth subsystem have { HEAD ~ S copies } of { TAIL ~ the data line }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL