Hi All, We should try to reach a decision on this issue before the end of the week. I think it would be helpful to hear some other opinions. So far, we have three options to choose from: 1) Require that the displacement unit be the same at all processes for MPI_Win_allocate_shared(). 2) Allow different displacement units at each process in shared memory windows and allow processes to determine the displacement unit at remote processes via MPI_Win_shared_query(). This is in addition to the MPI-2 self-query already possible with MPI_Win_get_attr(MPI_WIN_DISP_UNIT). 3) Allow different displacement units at each process in shared memory windows and provide only the MPI-2 self-query already possible with MPI_Win_get_attr(MPI_WIN_DISP_UNIT). Manual communication would be needed to exchange disp_unit information. A (very) rough summary of the discussion on this issue: * Given that non-uniform disp_unit values are currently allowed, processes may need to use disp_unit in address calculations. * Requiring programmers to use the disp_unit at each process in address calculations diminishes the usefulness of the shared memory programming model. It's also not clear if there is a use case to support the non-uniform disp_unit model. Thanks, ~Jim.