Hi, I am working on implementing MPI_T events in MPICH and came across a potential issue. MPI_T_EVENT_SET_DROPPED_HANDLER does not take a user_data argument, but the callback signature and standard text suggest that it should be there. The argument user_data is the pointer to user-allocated memory that was passed to the MPI implementation during callback registration. Am I correct in understanding that user_data is specified for each callback registration? I.e. if a user registers callbacks for different safety levels, those callbacks can be associated with different user_data buffers. If so, it seems the dropped handler registration is missing this functionality. Thanks, Ken