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