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