{TAIL ~ The percent area A} of the plane in {HEAD ~ the slide surface} is set in a range of A≧50% 
{ TAIL ~ The percent area A } of the plane in { HEAD ~ the slide surface } is set in a range of A≧50 %
TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH