Folks who commission from the ranks (CFR - which is distinctly different from becoming an officer with previous NCM service) from the non-engineering/technical trades are usually commissioned as MARS officers, but not employed as such. We used to call them "71Z." In other words, they are MARS officers in name only and are usually employed as instructors in schools (often in the field of their previous NCM trade - e.g. An ex communications chief instructing junior officers at VENTURE in communications), Area Cadet Oficers, recruiters, various staff positions, etc. They can do many things where there experience is valuable, but where they don't have to be able to navigate or con ships. Only if they want to do the traditional MARS stuff, will they have to take the courses.