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