In some cases, multiple computer systems may be connected, {HEAD ~ each} residing at {TAIL ~ a node} of a network 
In some cases , multiple computer systems may be connected , { HEAD ~ each } residing at { TAIL ~ a node } of a network
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD REL REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH