If you are using the Parallel Environment's (PE) mpi module with an older version of the XL Fortran compiler, you might hit this error message:
1514-220 (S) Module symbol file for module mpi is in a format not recognized by this compiler. Please compile the module with this compiler.
The mpi module was generated using XL Fortran 12.1, so it's incompatible with earlier versions of XL Fortran. We recently published a technote about this. Consider upgrading to take advantage of the extra type-checking offered by this module.
If you're unfamiliar with the mpi module, you can find more information here.