{HEAD ~ A measuring unit} measures {TAIL ~ the tool position} with an accuracy higher than that to which the first drive unit can respond 
{ HEAD ~ A measuring unit } measures { TAIL ~ the tool position } with an accuracy higher than that to which the first drive unit can respond
HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH