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