Deficits are expressed in units of metric tons of carbon dioxide equivalent and are calculated under OAR 340-253-1020. (21) Diesel fuel or ???diesel??? means a compression ignition engine fuel conforming to the specifications of either ASTM D975 or ASTM D7467. (22) ???Diesel substitute??? means any fuel, other than diesel fuel, that may be used in an engine designed for diesel use. (23) ???Ethan