, roll-on/roll-off cargo ships, short-sea
passenger ships, specialized tankers, tanker tug-barges, and
vehicle carriers.

A captive register is a register of ships maintained by a
territory, possession, or colony primarily or exclusively
for the use of ships owned in the parent country; it is also
referred to as an offshore register, the offshore equivalent
of an internal register. Ships on a captive register will
fly the same flag as the parent country, or a local variant
of it, but will be subject to the maritime laws and taxation
rules of the offshore territory. Although the nature of a
captive register makes it especially desirable for ships
owned in the parent country, just as in the internal
register, the ships may also be owned abroad. The captive
register then acts as a flag of convenience register, except
that it is not the register of an independent state.

A flag of convenience register is a national register
offering registration to a merchant ship not owned in the
flag state. The major flags of convenience (FOC) attract
ships to their registers by virtue of low fees, low or
nonexistent taxation of profits, and liberal manning
requirements. True FOC registers are characterized by having
relatively few of the registered ships actually owned in the
flag state. Thus, while virtually any flag can be used for
ships under a given set of circumstances, an FOC register is
one where the majority of the merchant fleet is owned
abroad. It is also referred to as an open register.

A flag state is the nation in which a ship is registered and
which holds legal jurisdiction over operation of the ship,
whether at home or abroad. Maritime legislation of the flag
state determines how a ship is crewed and taxed and whether
a foreign-owned ship may be placed on the register. An
internal register is a register of ships maintained as a
subset of a national register. Ships on the internal
register fly the national flag and have that nationality but
are subject to a separate set of maritime rules from those
on the main national register. These differences usually
include lower taxation of profits, use of foreign nationals
as crew members, and, usually, ownership outside the flag
state (when it functions as an FOC register). The Norwegian
International Ship Register and Danish International Ship
Register are the most notable examples of an internal
register. Both have been instrumental in stemming flight
from the national f