"Last month's 'Extreme Linux' introduced MPI-2, the latest
Message Passing Interface (MPI) standard. MPI has become the
preferred programming interface for data exchange--called message
passing--for parallel, scientific programs. MPI has evolved since
the MPI-1.0 standard was released in May 1994. The MPI-1.1
standard, produced in 1995, was a significant advance, and the
MPI-2 standard clarifies and corrects the MPI-1.1 standard while
preserving forward compatibility with MPI-1.1. A valid MPI-1.1
program is a valid MPI-2 program..."