long mpiFilterConfigGet(MPIFilter       filter,
                        MPIFilterConfig *config,
                        void            *external)

FilterConfigGet gets a Filter's (filter) configuration and writes it into the structure pointed to by config, and also writes it into the implementation-specific structure pointed to by external (if external is not NULL).

The Filter's configuration information in external is in addition to the Filter's configuration information in config, i.e, the Filter's configuration information in config and in external is not the same information. Note that config or external can be NULL (but not both NULL).

external either points to a structure of type MEIFilterConfig{} or is NULL.