The design approval phase of PMA certifies that a replacement or modification article complies with the airworthiness standards of eligible products (aircraft, engine, or propeller). The applicant shows this compliance through tests and computations unless the article is identical to the article design on a type-certificated product. Identicality means that an article is the same in all respects to an article design in a type-certificated product. Evidence of license agreement shows this identicality.