Hi all, In the latest mpi-4.0 RC pg 758, ln 16 describing MPI_T_EVENT_GET_INFO: If the argument to enumtype provided by the user is the MPI_T_ENUM_NULL pointer, no enumeration type is returned. This differs from previous get info functions. E.g. MPI_T_PVAR_GET_INFO: ... or the argument enumtype is the null pointer, no enumeration type is returned. IMO, the user providing MPI_T_ENUM_NULL to enumtype doesn't make sense. The user would pass a null pointer, as it is an output argument. Ken