an Entity references as follows:
National service is the system of voluntary government service, usually military service. Conscription is mandatory national service. The term national service comes from the United Kingdom's National Service (Armed Forces) Act 1939. The length and nature of national service depends on the country in question. In some instances, national service is compulsory, and citizens living abroad can be called back to their country of origin to complete it. In other cases, national service is voluntary.