### Question
How does NATURAL GAS define heavy petroleum fuel oil?


### Answer
Under *15 U.S.C. § 717y*, **heavy petroleum fuel oil** is defined as:

> number 4, 5, or 6 fuel oil which is domestically refined

#### Citation:
  - *15 U.S.C. § 717y*
  - Heading: **CHAPTER 15B-NATURAL GAS**

