{HEAD ~ The method} 9, further comprising resetting the reference position to zero in response to an input command from {TAIL ~ an operator} of the tool 
{ HEAD ~ The method } 9 , further comprising resetting the reference position to zero in response to an input command from { TAIL ~ an operator } of the tool
HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH