Regulation and Compliance Terms
The public instruments that bind a ship and the bodies that enforce them: the carbon and sulphur rules, the flag, class and port-state regimes, and the safety codes behind them.
Carbon Intensity Indicator (CII)
An IMO operational measure of how much CO₂ a ship emits per unit of transport work, graded A to E each year.
Classification Society
An organisation that sets technical standards for ship construction and surveys vessels against them throughout their life.
COLREGs
The international "rules of the road" governing how ships navigate to avoid collisions at sea.
Energy Efficiency Design Index (EEDI)
An IMO design standard that caps the CO₂ emitted per unit of transport capacity for newly built ships.
Energy Efficiency Existing Ship Index (EEXI)
A one-time IMO design-efficiency standard that existing ships must meet, the in-service counterpart of the EEDI for new ships.
Flag State
The country in which a ship is registered, whose laws she sails under and which is responsible for her regulatory oversight.
International Maritime Organization (IMO)
The United Nations agency that sets global rules for ship safety, security and pollution prevention.
ISM Code
The IMO safety-management standard requiring shipping companies to operate a documented Safety Management System.
MARPOL
The IMO convention preventing pollution from ships: oil, chemicals, sewage, garbage and air emissions, across six annexes.
Memorandum of Understanding (MOU)
A regional agreement coordinating port-state-control inspections, such as the Paris and Tokyo MOUs.
Port State Control (PSC)
The inspection of foreign ships in national ports to verify they meet international safety and environmental standards.
Scrubber
An exhaust gas cleaning system that removes sulphur oxides from a ship’s emissions, letting her burn cheaper high-sulphur fuel.
Very Low Sulphur Fuel Oil (VLSFO)
Marine fuel blended to the global sulphur cap: the compliant fuel for most waters since the IMO sulphur rules took effect.
Where these terms show up on The Maritime
About these definitions. Plain-English reference definitions of standard shipping concepts: our own explanations, not legal advice. Each term page opens with the definition, explains how the concept works and links to the desk where The Maritime measures it. The first entry is Carbon Intensity Indicator (CII).
Glossary last reviewed: .