The rest are set to default values.
AREA is the data area, meaning the area from which to select the data to plot.
The rest of these variables are currently set to defaults by the sfmap.nts file. However, it's a good idea to know how they work, so that later you can change them if you need to. The map projection directly affects the way the map looks on the screen. Think about the way the continental US looks in the Mercator projection versus the Polar Stereographic projection. The projection can be specified as a simple map projection , or as a full map projection .