Unique to GDL, the coordinates used are always represented as 64-bit doubles. Longitude and latitude coordinates are always in degrees. Positive numbers represent the Eastern and Northern hemispheres, respectively, and negative numbers represent the Western and Southern hemispheres. For example, the point 140W by 30N would be represented as –140.0,30.0. The library always assumes that the longitude coordinate is the horizontal direction and the latitude coordinate is the vertical direction. Support is not provided for user coordinates.