Accession
A1. The IMO and the international regulatory frameworkDefinition
Act by which a non-signatory state becomes party to a treaty already in force.
Accession is the act by which a state that did not sign a treaty during the signature period becomes a party to it, with the same legal effect as ratification. For IMO conventions the instrument of accession is deposited with the Secretary-General. Most parties to long-standing instruments such as SOLAS 1974 and MARPOL joined by accession rather than original signature.
Source: Vienna Convention on the Law of Treaties, Article 15