用字母来表示东\西\南\北\东北\东南\西南和西北的地理位置.

各个方位的英文全称是：
east
west
south
north
northeast
southeast
southwest
northwest
所以用字母来表示八个方位，就是以上英文的简写：
E/W/S/N/NE/NS/SW/NW

east
west
south
north
northeast
southeast
southwest
northwest

东E/西W/南S/北N/东北NE/东南SE/西南SW/西北NW

E/W/S/N/NE/NS/SW/NW