Alternatively L1 and D2 may be functionally viewed as {HEAD ~ a smoothing filter} with {TAIL ~ an input} at terminal 15 
Alternatively L1 and D2 may be functionally viewed as { HEAD ~ a smoothing filter } with { TAIL ~ an input } at terminal 15
OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH