During our meeting today we decided that MPI_Count should be at least as large as an MPI_Aint. We already had the restriction that it had to be as large as a C/Fortran integer. We want both restrictions (they cannot be combined because there is no guarantee that MPI_Aint > integer). I'll throw this out as a starting point for discussion: 2.5.8 Last sentence change to: The size of the MPI_Count type is determined by the MPI implementation with the restriction that it must be minimally capable of encoding a C int and Fortran INTEGER and any value that may be stored in an MPI_Aint type. Rational thingy: MPI_Count is used to communicate both the number of elements in a datatype and the bounds of a datatype. The number of elements in a datatype is specified at creation time using a C int or Fortran INTEGER. The bounds may be specified using an MPI_Aint. So, I was especially brief here. I did not want to get into the "new" routines vs. "old routines", but if you attempt to go into more depth than what I said, you will inevitably end up going down that path. I can think of a thousand ways not to say it, but its hard to come up with a good way. Dave *