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