Plates bearing a specific manufacture number, for use in certain types of aircraft — Not backed, without internal layers of other material, - in coils or in coiled strips, in cut-to-length sheets, or in the form of circles; of a thickness exceeding 0,2 mm but not exceeding 6 mm; - in plates, of a thickness exceeding 6 mm — Of a thickness of not less than 0,8 mm, for use in the manufacture of aircraft parts