19 CFR § 10.12 - Definitions.
(b) Assembly. “Assembly” means the fitting or joining together of fabricated components.
(c) Exemption. “Exemption” means the deduction of the cost or value of products of the United States which were assembled abroad in accordance with the requirements of subheading 9802.00.80, Harmonized Tariff Schedule of the United States (19 U.S.C. 1202), from the full value of the assembled article.
(e) Product of the United States. A “product of the United States” is an article manufactured within the Customs territory of the United States and may consist wholly of United States components or materials, of United States and foreign components or materials, or wholly of foreign components or materials. If the article consists wholly or partially of foreign components or materials, the manufacturing process must be such that the foreign components or materials have been substantially transformed into a new and different article, or have been merged into a new and different article.