Hi Jeff, Thanks - I looked through quickly - there's nothing outlandish it there, IMHO - seems sensible/modest. Slide 9 question "both mpi.h and mpi_abi.h in same program?" Do you mean "in the same translation unit" or "in different libraries linked together into a single binary" or something else? I'm thinking that the World model encourages the user to pass a communicator from the place where MPI_INIT was called into each sub-program/library - there must be agreement between them on the type/value. There are a bunch of what-if scenarios here: passing an MPI_Status from one place to another using a parameter/return value suggests your option 1 is the correct answer there (language copy would work). Best wishes, Dan. From: mpiwg-abi <[email protected]> On Behalf Of Jeff Hammond Sent: 24 January 2023 15:01 To: [email protected] Subject: [mpiwg-abi] MPI-5 ABI proposal As requested, I have made a concrete proposal for the MPI-5 ABI. https://docs.google.com/presentation/d/1cU9ewMUa7w3eaRVtfzov8NinyjzNSp5nF_pe... Request edit access if you want to paint the bike shed with me. Jeff -- Jeff Hammond [email protected]<mailto:[email protected]> http://jeffhammond.github.io/