Programs, such as Fortran programs, reside at low core memory addresses (just above the Supervisor). Fortran allocates space at the highest addresses for any variables and arrays declared COMMON. If a follow-on phase of the program contains a corresponding COMMON declaration, then information in this common area can be shared among phases. Phases could omit the COMMON declaration without problem, provided those phases were not so large as to have their program code invade the common area. COMMON storage not only shares data between phases; lower-memory COMMON variables can be used to pass data among a main program and subprograms within a single phase, though the data could be lost on moving to the next phase.