Reference Radiographs are nondestructive testing standards universally accepted because of their high reliability in accept-reject actions. These reference radiographs illustrate the categories and severity levels of discontinuities that may occur in aluminum-alloy and magnesium-alloy die castings. They are intended to provide: A guide enabling recognition of discontinuities and their differentiation both as to type and severity level through radiographic examination. Example radiographic illustrations of discontinuities and a nomenclature for reference in acceptance standards, specifications, and drawings. The set of reference radiographs consists of five 8-1/2 by 11 in. cardboard frames containing radiographs covering discontinuities in aluminum and magnesium alloy die-castings. The first four frames each contain two sets of four graded levels of increasing severity, while the last frame contains two ungraded radiographs. The five frames are contained in a 10-1/2 by 11-1/2 in. ring binder.