This resets counter 40 to zero on the possibility that a few counts may have been registered due to interference or {HEAD ~ spurious signals} appearing at {TAIL ~ input} 42 at some previous time 
appearing at
This resets counter 40 to zero on the possibility that a few counts may have been registered due to interference or { HEAD ~ spurious signals } appearing at { TAIL ~ input } 42 at some previous time
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL REL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH