SOM

 Projection     : Space Oblique Mercator
 General class  : modified cylindrical
 Characteristics: basically conformal
 Earth model    : ellipsoid or sphere

Defining the MAPUNITS:

 MapUnits "som"     ! Standard name
 MapUnits "som e0"  ! Standard name and ellipsoid

Other parameters:

 LandsatNumber "landsat_number"  ! Required
 LandsatPath   "path_number"     ! Required
 FalseEasting  "false_easting"   ! Optional, default is zero
 FalseNorthing "false_northing"  ! Optional, default is zero

Possible errors:

 E100, "Invalid data" - In initializing for the projection, the 
        Landsat satellite number and/or path number are out of range.
 E330, "Calculation failed to converge to a solution" - In converting 
        from projection coordinates to geographic coordinates, too 
        many iterations were made.