allocate.c: Used for initial allocation of MPI processors child.c: Does the work assigned to children. err-handler.c: Handles errors. extern.h: Has all the external variables. Do a #define extern in one file to make sure that these externs are also defined. Done in allocate.c in the current set up. hello_world.c: Contains the main/driver program. This one executes all teh children. localmpi.h: All the local function prototypes and #define'd constants. master.c: Handles returns and cleans up.