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