They should either be empty, or contain only ballast or other material of such a nature or so disposed as to make a thorough inspection possible.
A rule in major IMO conventions that, when inspecting a ship flying the flag of a State which is not a party to the Convention, Port State Control Officers must ensure that the treatment of such a ship and its crew is not more favourable than that of a ship flying the flag of a State party to that Convention. For example, many States have not yet ratified or acceded to MARPOL Annex VI, but ships flying their flags will still be required to meet the requirements of Annex VI to pass port State control inspections.
Broadly, ships flying flags of Party States, when on international voyages. Each chapter (I to XII) defines the ships to which that chapter applies. Application may depend on type of ship (e.g. chapter X - High Speed Craft), or date of build (e.g. chapter II-1 - Construction - subdivision and stability, machinery and electrical installations), area of operation (e.g. chapter V - Safety of navigation), tonnage (e.g. chapter IV - Radio communications) or cargoes (e.g. chapter VI - Carriage of cargoes and oil fuels). Each chapter may also exempt certain ships from the chapter's requirements.
International Load Line Exemption Certificates may be issued to ships of Convention size on international voyages in certain circumstances (see below). UK Load Line Exemption Certificates may be issued to ships which do not ply internationally or which are not Convention ships (i. e. are less than 150 GT or less than 24 m in length).
For example: costs of hiring a tug to refloat a stranded ship with cargo onboard; cost of discharging cargo in order to refloat a stranded ship or to carry out repairs at a port of refuge; salvage costs; agency fees at a port of refuge; surveyors' fees; warehousing charges; port charges; master's and crew's wage while a ship is being repaired; and Average Adjuster's fee.