The code should be written in Fortran 77, Fortran 90, High Performance Fortran, or C. Data should be passed between processors by explicit message passing. PARKBENCH does not specify which message passing system should be used, but one that is available on a number of parallel platforms is preferable. Eventually it is expected that MPI will become the message passing system of choice, but in the meantime portable systems such as PVM, PICL, Express, PARMACS, and P4 are acceptable alternatives. The codes in the Compact Applications suite should not contain any assembly coded portions, although assembly code may be used in optimized versions of the code.