MPI-4.1 is a minor update to the MPI standard. It contains mostly corrections and clarifications to the MPI-4.0 document. Several routines, the attribute key MPI_HOST, and the mpif.h Fortran include file are deprecated. A new routine provides a way to inquire about the hardware on which the MPI program is running. Any valid MPI-4.0 program is a valid MPI-4.1 program with the exception of semantic changes listed in Chapter Semantic Changes and Warnings.