Liner conferences may circumvent procedures for consultations on basic freight rates by the device of increasing surcharges for bunker prices or currency adjustment factors, often under formulae which shippers claim are not comprehensible. Currency adjustment surcharges may be introduced or increased as a result of the weakening of the world monetary situation and currency exchange inequities. Bunker price surcharges may be introduced or raised as a result of increased oil prices. For such reasons, while it is easier to assess the position in an individual trade, it is very difficult to judge the reasonableness of the levels of surcharges in general.