I agree with Dick. We're getting very strong ISV feedback that an MPI-3 compatibility break will constitute a serious adoption barrier for them.

The other option would be to have an extra function like MPI_Get_count that extracts internal information from MPI_Status objects. Can that be implemented without breaking compatibility? Greg Bronevetsky Lawrence Livermore National Lab (925) 424-5756 [email protected] http://greg.bronevetsky.com