The projection settings in a MapServer map file are at two levels: the output map projection and the projection of the input layers of features to be drawn. Example A-1 shows a sample of the projection settings for an output map.
Example A-1. Example settings for the map to be rendered using an Albers Equal Area projection
PROJECTION "proj=aea" "ellps=WGS84" "lat_0=10" "lon_0=-90" END
The settings may look confusing to anyone unfamiliar with projections, but they have a straightforward purpose. If you can get these four settings clear in your mind, you'll be able to handle most projections with ease.
The first line in Example A-1,
"proj=aea", is the most ...