Organic compounds that occur in crude oils and petroleum products containing elements other than carbon and hydrogen, such as nitrogen, sulfur, and/or oxygen. NSO compounds also may contain to vanadium, nickel, sodium, and potassium. Compounds in this fraction are sometimes called non-hydrocarbons or resins. These NSO compounds are usually present in small quantities but may have considerable influence on product quality. Other fractions include saturates, aromatics, and asphaltenes.