Credential means any or all of the following:

(1) Merchant mariner's document.

(2) Merchant mariner's license.

(3) STCW endorsement.

(4) Certificate of registry.

(5) Merchant mariner credential.

Merchant mariner credential or MMC means the credential issued by the Coast Guard under 46 CFR part 10. It combines the individual merchant mariner's document, license, and certificate of registry enumerated in 46 U.S.C. subtitle II part E as well as the STCW endorsement into a single credential that serves as the mariner's qualification document, certificate of identification, and certificate of service.