This Appendix describes the operation of ten subroutines used to support the AUXILIARY and MAIN programs of ALSIM. Flow charts and listings of all programs are provided. The major portion describes the FORTRAN subprogram FORTM which is used to read input data, assign values to matrix elements, perform matrix searches and assign parameters to GPSS transactions during simulation model execution. Six other subroutines, mostly written in IBM System/370 Assembly Language, are used in the initialization phase of the simulation to link FORTM to the MAIN program and to provide an in-core read and write capability. Two additional assembly language subroutines and a FORTRAN subroutine are used during simulation of the airport landside. The first assembly language subroutine assigns the number of passenger bags to be retrieved by the deplaning passenger transaction and generates random numbers to simulate waiting times at the bag claim facility. The second subroutine performs the same function as ASSIGN and LOGIC blocks of GPSS, but is FORTRAN callable. The FORTRAN subroutine of this group detects argument errors of the previous subroutine and prints error messages.