There are two recognized standards of Gas Oil that are currently in use: BS 2869 Class A2 and BS 2689 Class D. Class A2 has a maximum sulphur content of 10ppm and is used for off road vehicles and equipment, while Class D has a maximum sulphur content of 1000 ppm and can only be used for heating or static generators. Class A2 gas oil may be used for either application.