Reference

Captain's license glossary

The acronyms every course seller uses without expanding them, defined plainly and in the order they matter to a first-time applicant.

What do MMC, OUPV, and TWIC stand for?

MMC is the Merchant Mariner Credential, the physical document the National Maritime Center issues once you qualify. OUPV is Operator of Uninspected Passenger Vessels, the six-pack license for up to six paying passengers. TWIC is the Transportation Worker Identification Credential, a separate Transportation Security Administration background check most mariners also need. The full list below defines every acronym you will hit on a course seller's page.

Assessment period: A recommended waiting time after a criminal conviction, published in tables at 46 CFR 10.211, that the National Maritime Center applies before normally granting a credential. It runs from completion of the sentence and is longer for more recent or more serious offenses. Eligibility with a record.
Code of Federal Regulations (CFR): The published U.S. federal regulations. Merchant mariner credentialing, including sea-time credit and the OUPV and Master requirements, is governed largely by Title 46 of the CFR, Part 11.
eVTR (electronic Vessel Trip Report): A required electronic trip report filed after each fishing trip by federally permitted for-hire and commercial vessels in the Greater Atlantic (Northeast and Mid-Atlantic) region and by Atlantic HMS permit holders, typically within 48 hours of completing the trip. It is the Atlantic-coast counterpart to the Southeast's SEFHIER reporting system: which one applies depends on which federal permit and region your trips fall under. See eVTR in a state's requirement stack.
Gross Register Tonnage (GRT): A measure of a vessel's internal volume, not its weight, used to set the Master license tiers (25, 50, and 100 Ton). The tonnage of the vessels you served on and the vessel you intend to operate affects which Master tier you qualify for.
Highly Migratory Species (HMS): NOAA Fisheries' term for Atlantic tuna, sharks, swordfish, and billfish (blue and white marlin, roundscale spearfish, sailfish), managed under their own federal permit system because they range across huge distances and jurisdictions. A for-hire operator taking anglers after any of these needs the Atlantic HMS Charter/Headboat permit plus the HMS Angling permit, with an added shark endorsement to target sharks. See the offshore trip context in the insurance guide.
Inland route: A route designation for inland waters, bays, sounds, and Great Lakes service. You earn an Inland endorsement from sea time documented on those waters. It does not extend offshore, so it is narrower than a Near Coastal endorsement. How sea time sets your route.
Limited-entry permit: A federal fishery permit issued under a moratorium: NOAA or the state stopped issuing new permits at some point, so the only way to get one today is to buy or lease an existing permit tied to a specific vessel or operator. Alaska's Charter Halibut Permit and the Gulf of Mexico reef fish for-hire permit both work this way; a new operator generally cannot apply cold and must acquire one on the secondary market. See Alaska's limited-entry halibut permit.
Master license: A captain's license that authorizes commanding an inspected vessel and carrying more than six paying passengers, tiered by vessel tonnage as Master 25, 50, or 100 gross register tons. The tier you earn depends on documented sea time on vessels of qualifying size. OUPV vs Master.
Merchant Mariner Credential (MMC): The single federal document issued by the U.S. Coast Guard National Maritime Center that authorizes a person to work aboard a U.S. vessel. The captain's license is an officer endorsement, such as OUPV or Master, printed in this credential.
National Maritime Center (NMC): The U.S. Coast Guard unit that evaluates applications and issues the Merchant Mariner Credential. The NMC makes the final determination on eligibility, sea-time credit, and medical fitness for every captain's license.
Near Coastal: A route designation covering ocean waters generally out to 100 nautical miles offshore. You earn a Near Coastal endorsement when enough of your documented sea time was on near-coastal or ocean waters, and it also lets you work inland waters. OUPV routes explained.
Operator of Uninspected Passenger Vessels (OUPV): The entry-level captain's license, commonly called the six-pack because it allows carrying up to six paying passengers on an uninspected vessel. It is issued as either an Inland or a Near Coastal route depending on where your sea time was earned.
Protection and Indemnity (P&I): The standard maritime term for liability insurance: coverage for your legal liability to others, most importantly a paying passenger's injury, plus things like wreck removal or damage to another vessel or a dock. It is separate from hull insurance, which covers physical damage to your own boat. Marinas, fuel docks, and booking platforms typically ask charter operators for proof of P&I, not hull. Read the full insurance norms guide.
Regional Examination Center (REC): A local U.S. Coast Guard office where mariners submit applications, verify identity, and take exams. Your application routes through an REC before evaluation at the National Maritime Center.
Small Vessel Sea Service Form (CG-719S): The Coast Guard form that documents your sea time, filled out per vessel and signed by that vessel's owner or operator (or self-certified if you own it). It records the days, water type, and tonnage the National Maritime Center evaluates. The CG-719 forms walkthrough.
Snapper-grouper complex: The South Atlantic Fishery Management Council's Snapper Grouper Fishery Management Plan, the largest FMP in its jurisdiction: 55 species of snappers, groupers, and related reef fish managed together from North Carolina through the Atlantic coast of Florida. A federal permit applies to for-hire vessels targeting these species in federal waters, separate from any state charter license. See how it applies on Florida's charter page.
Standards of Training, Certification and Watchkeeping (STCW): An international convention setting minimum training and certification standards for mariners. Some captain's license routes and larger tonnage or offshore endorsements require associated STCW certificates such as basic training.
Transportation Worker Identification Credential (TWIC): A biometric security card issued by the Transportation Security Administration that most merchant mariners must hold. You generally need a TWIC before or alongside your captain's license application, and it has its own separate processing time.