### Question
How is the term retrofit defined?


### Answer
The term **retrofit** is defined in *42 U.S.C. § 7675* as the following:

> to upgrade existing equipment where the regulated substance is changed, which—


(i) includes the conversion of equipment to achieve system compatibility

#### Citation:
  - *42 U.S.C. § 7675*
  - Heading: **CHAPTER 85-AIR POLLUTION PREVENTION AND CONTROL > SUBCHAPTER VII-AMERICAN INNOVATION AND MANUFACTURING**

