In the United States, the Military Standard (also written as MIL-STD) is enforced by the Department of Defense and maintained by the U.S. Air Force, Army, and Navy. It exists to ensure products meet specific requirements for various defense-related purposes.
Note: The MIL-STD is not only used in the Military sector but also across non-defense organizations because of the thorough test methods that validate a product’s readiness for extreme conditions.
The letter that follows the Military Standard depicts the current revision. There is no particular time-frame that must pass for a revision to occur but it does go in alphabetical order. The current revision, issued Jan. 31, 2019, is MIL-STD-810H.