In MO there are state appointed Rules and Mechanics interpreters. I think there are around 5 or 6 rules interpreters and 5 or 6 mechanics intrepreters from across the state, usually in certain geographic areas. The main job duty of these folks is to hold preseason rules meetings (all officials must attend) and mechanics clinics (1-3 year officials must attend). In addtion to that, usually just be a point of contact person for any officials/coaches in the area that have a question regarding rules or mechanics. Replacements are usually made based on recommendations from the outgoing intrepreter.