It applies to all ships irrespective of tonnage or voyage other than ships navigating exclusively in inland waters or waters within, or closely adjacent to, sheltered waters or areas where port regulations apply. A flag State can apply some flexibility in applying particular requirements based on the gross tonnage (GT) of ships and voyages. E.g.:- the requirement for certification and inspection of working and living conditions on a ship is not mandatory for ships under 500GT not taking international voyages or voyages between foreign ports. A determination can also be made under Article II paragraph 6. Ships or seafarers not on international voyages  need not comply with some requirements for English language documents such as medical certificates.