{HEAD ~ A message} is output when the degree of the wear position deviates from the degree of the reference position by more than the degree of {TAIL ~ wear} permissible 
{ HEAD ~ A message } is output when the degree of the wear position deviates from the degree of the reference position by more than the degree of { TAIL ~ wear } permissible
HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL OTH