Modification to the MOS system is a dynamic process that affects the Human Resource Development Process (HRDP), i.e . Total Force Structure Process (TFSP), Manpower, and Training Development Processes. MOS system modification requires a clear understanding of the process to produce timely and coordinated staff actions which in turn prevent erroneous classifications and assignment of personnel and unsynchronized modifications to TIOs, and manpower and training plans. MOS system modification, force structure changes, and manpower and training management are calibrated annually. Enclosure (1) explains terms used in the MOS system modification process.