A system 16 wherein the network comprises a plurality of receiving units in {HEAD ~ communication} with {TAIL ~ a server} 
with
A system 16 wherein the network comprises a plurality of receiving units in { HEAD ~ communication } with { TAIL ~ a server }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL