I haven't confirmed this yet, but I'm not filing a bug because perhaps this instead should be the subject of an MPI-3 erratum discussion. For those who - like me - (didn't) don't know what "horks" mean, I recommend that you do not Google it. The definition from urbandictionary.com is quite foul. Best, Jeff ---------- Forwarded message ---------- From: Michael Raymond <[email protected]> Date: Thu, Nov 15, 2012 at 1:15 PM Subject: Re: [Mpi-forum] MPI 3.0 implementation slides To: Jeff Hammond <[email protected]> As a way of saying thank you for all the great info: MPIR_Comm_split_type_impl() horks on split_type == MPI_UNDEFINED even though the 3.0 standard allows it. -- Michael A. Raymond SGI MPT Team Leader (651) 683-3434 -- Jeff Hammond Argonne Leadership Computing Facility University of Chicago Computation Institute [email protected] / (630) 252-5381 http://www.linkedin.com/in/jeffhammond https://wiki.alcf.anl.gov/parts/index.php/User:Jhammond