{TAIL ~ Each downstream stage} has {HEAD ~ its input circuit} coupled to the output circuit of an upstream stage 
{ TAIL ~ Each downstream stage } has { HEAD ~ its input circuit } coupled to the output circuit of an upstream stage
TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH