SDN (Specially Designated National)

A person, entity, or vessel named on OFAC’s Specially Designated Nationals and Blocked Persons List. Their property and interests within US jurisdiction are blocked (frozen), and US persons are generally prohibited from dealing with them. Listings carry identifiers (passport, IMO number, MMSI, address) so screening can match across renaming and aliases. The 50 Percent Rule extends the block to entities owned 50 percent or more by SDNs. A designated vessel is blocked property, barring most dealings worldwide for US persons.