I have submitted a new 2.2 proposal to add several new datatypes to the C and C++ bindings, most of them in order to keep up with the C99 standard. This proposal also adds MPI_AINT and MPI_OFFSET as predefined datatypes. Comments are welcome. https://svn.mpi-forum.org/trac/mpi-forum-web/wiki/mpi22/ NewPredefinedDatatypes -Dave Goodell Argonne National Laboratory