Manufacturer has the meaning given in section 216 of the Clean Air Act. In general, this term includes any person who manufactures a stationary engine for sale in the United States or otherwise introduces a new stationary engine into commerce in the United States. This includes importers who import stationary engines for resale.
40 CFR § 60.4248
As used in this subpart, all terms not defined herein shall have the meaning given them in the CAA and in subpart A of this part.