we need to have a meeting to discuss how to implement handles and predefined handle constants e.g. MPI_COMM_WORLD and MPI_INT. i think we have consensus that we will do e.g. typedef struct MPI_ABI_Datatype * MPI_Datatype; since that is the only option that provides type-safety. there is an open question about using integer literal constants (MPICH-style) or addresses (OMPI-style). there are merits to both. i want to get consensus so that i can update the ABI proposal one way or the other.https://www.when2meet.com/?18843291-UxaiH is for scheduling. i will set the meeting time on Monday morning. i can host Teams or Google Meet. if you prefer Zoom, you can agree to host it. jeff -- Jeff Hammond [email protected] http://jeffhammond.github.io/