To date only a small number of routines have been generated for using this data file but more will be added in the future. Current routines allow for plotting the earth outline map in 3d or in a linear projection.
A data file (EARTH.DAT) which contains a map of the land/ocean interface and a set of routines to access this data has been included in the LONGLIB graphics library. The data file (of unknown origin) contains a list of latitudes and longitudes of the land/ocean edges at about a 10 km resolution. It is only a geographic map and does not contain political boundries. Although imperfect, it is more than adequate for large scale map drawing. It only shows continental boundaries and not political boundaries. Due to the high resolution, the EARTH.DAT file contains a lot of pen motions, requiring a long plotting time.
Fortran file unit 2 should be reserved for accessing the map data file by these routines. The logical name LONGLOC: must be assigned to be the location of the EARTH.DAT file. The routine LNDMAP is the general file read routine. It permits user specified map projection plotting.
Routines using the land outline file include those for plotting on 3d spheres, flat surfaces, etc. The general routine is LNDMAP with a simple linear 2-d plot in LANDMAP and a 3-d plot in EARTH3D.