Hi All, It looks like we forgot to include the removal of the "safe" qualifier from the tag argument as a part of the change to MPI_Intercomm_create: https://svn.mpi-forum.org/trac/mpi-forum-web/ticket/305 Specifying that the tag argument must be "safe" was made unnecessary by this change, since it eliminates the possibility of interference with user communication. ~Jim.