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