Coordinate systems used by the SNAP and concord programs are defined in a file called coordsys.def and stored in the same directory as the programs. If you need to use coordinate systems not defined in the default file they can either be added to this file, or you can use your own coordinate system file.
To use your own coordinate system definition file you can either specify the name of the file in the snap or concord command line, or set an environment variable COORDSYSDEF to reference the alternative file. For example:
SET COORDSYSDEF=c:\data\cslist.dat