All, An implementation of the MPI_Comm_split_type function is now publicly available in MPICH2 here: http://www.mcs.anl.gov/research/projects/mpich2/downloads/tarballs/nightly/trunk/ (please use r9071 or higher). The latest tarball will be generated in a few minutes. Thanks, -- Pavan -- Pavan Balaji http://www.mcs.anl.gov/~balaji