MARPOL 73/78
A3. Marine environmental legislation: MARPOL and its annexesDefinition
1973 Convention as modified by the 1978 Protocol.
MARPOL 73/78 is the combined instrument formed when the 1978 Protocol absorbed the 1973 Convention, which had not entered force on its own. The 1978 Protocol responded to a spate of tanker accidents and made Annex II optional for three years to ease ratification. The combined Annexes I and II entered into force on 2 October 1983, and the 1997 Protocol later added Annex VI on air pollution.
Source: MARPOL 73/78