See https://github.com/mpi-forum/mpi-standard/pull/875. I expect to read this more than once but we have to start somewhere. This PR defines the overall structure and specifies many of the ABI features. Many of the choices have strong consensus in the working group. The constants are not listed in tables yet because that's a bunch of LaTeX tedium for which I have not yet had time. Nothing in this PR depends on the values of the constants, and thus they can be added in a second PR. There are open issues regarding Fortran that will be added later, possibly as a different PR, depending on the working group discussion later today. The current proposal assumes one choice of MPI_Aint, which is only relevant in the context of exotic platforms like CHERI that have wide pointers (pointers are bigger than addresses). Jeff -- Jeff Hammond [email protected] http://jeffhammond.github.io/