40 CFR 410.41 - Specialized definitions.
(a) The term simple manufacturing operation shall mean all the following unit processes: Desizing, fiber preparation and dyeing.
(b) The term complex manufacturing operation shall mean “simple” unit processes (desizing, fiber preparation and dyeing) plus any additional manufacturing operations such as printing, water proofing, or applying stain resistance or other functional fabric finishes.
(c) For NSPS ( § 410.45) the term desizing facilities shall mean those facilities that desize more than 50 percent of their total production. These facilities may also perform other processing such as fiber preparation, scouring, mercerizing, functional finishing, bleaching, dyeing and printing.