The GALPROP code reads all the parameters from a file called galdef_vv_nnnnnn, where vv is the GALPROP version, and nnnnnn codes the current run. galprop is the main program which calls the routines to read the galdef file, read the nuclear data arrays, fill in the gas and radiation field distributions in the Galaxy, create cosmic rays, propagate particles, and finally store the output arrays.

The code consists of C++ and FORTRAN-77 files which are compiled separately and then linked to form a single executable file, and data files.

The GALPROP code uses relative paths to the folders and input/output files. Relative to the folder containing the code, other forders' paths are: