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