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