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