### Question
How is the "unit" defined?


### Answer
The term **unit** is defined in *42 U.S.C. § 7651a* as follows -

> a fossil fuel-fired combustion device

#### Citation:
  - *42 U.S.C. § 7651a*
  - Heading: **CHAPTER 83-ENERGY EXTENSION SERVICE > SUBCHAPTER IV&ndash;A-ACID DEPOSITION CONTROL**

