46 CFR 12.201: General requirements for national and STCW rating endorsements.

(a) General. (1) An MMC issued to a deck or engineer officer will be endorsed for all entry-level ratings and any other ratings for which they qualify under this part. An applicant for any STCW endorsement must hold the appropriate national endorsement, unless otherwise specified.

(2) The authorized holder of any valid rating endorsement may serve in any capacity in the staff department of a vessel, except in those capacities requiring a staff officer; except that whenever the service includes the handling of food, no person may be so employed unless their credential bears the Food Handler's endorsement indicated by the notation “(F.H.)”.

(3) When an applicant meets the requirements for certification set forth in this part, the Coast Guard will issue the appropriate endorsement.

(b) Physical and medical requirements. The physical and medical requirements applicable to the endorsements in this subpart are found in 46 CFR part 10, subpart C.