In step 154, it is checked to determine {TAIL ~ whether or not a command} to change the display size or {HEAD ~ position} has already been inputted 
In step 154 , it is checked to determine { TAIL ~ whether or not a command } to change the display size or { HEAD ~ position } has already been inputted
OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH