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