Abstract: An embodiment of the present invention is directed to a method for compiling, storing, and interpreting, as often as needed, a representation of any MPI datatype, including the steps of compiling a tree representation of an MPI datatype into a compact, linear data gather scatter program (DGSP) wherein the DGSP is of a form general enough to encode an arbitrarily complex datatype, registering the compact linear DGSP with a communications subsystem for later interpretation by the subsystem for at least one of sends, receives, packs and unpacks, creating a registered DGSP, and interpreting the registered DGSP. In one embodiment of the present invention, the form of the DGSP uses a single generalized representation. In another embodiment the single generalized representation covers any of the arbitrarily complex datatype patterns that can arise in this context.