THE United States Coast Guard has published a final version of what owners and tank vessel operators have to do when responding to worst case discharges of oil, or threats of such discharges. These guidelines for owners and tank vessel operators are modifications to requirements by the US Coast Guard. On Febrary 5, 1993, the US Coast Guard issued an interim final rule (IFR) for Tank Vessel Response Plans. As mandated by the Oil Pollution Act of 1990, the IFR set requirements for owners and operators of tank ships to develop and submit plans for responding to actual or threatened worst case discharges of oil, a discharge of the ship's cargo in adverse weather conditions. Requirements also include response plans for average most probable discharges and maximum most probable discharges, and the designation of a qualified individual to direct contracted response resources. The IFR set requirements for tank vessels carrying oil as cargo in bulk, except offshore supply vessels and fishing ships of less than 750 gross tonnes. In accordance with the Federal Government's Edible Oil Regulatory Reform Act, the final rule sets separate sections for requirements associated with petroleum and non-petroleum oils. Specific response plan requirements for petroleum and more flexible requirements for non-petroleum oils are essentially intact; but they are addressed in separate sections to facilitate requirement for future modification justified by more experience and research.