What does AN stand for in military nomenclature?

In military nomenclature, "AN" stands for "Army-Navy." This designation is used to identify specific standards and specifications established for materials and equipment used by both the Army and the Navy. The Army-Navy system was developed to ensure interoperability and standardization across different military branches, which is crucial for maintaining effective operational capabilities. This nomenclature system simplifies communication and procurement processes, as it provides a common reference for the various divisions within the military when it comes to equipment and materials used in operations.