Whenever a material, part, process, or appliance is required to be approved under this Part, it may be approved:
(a) under an APMA; or
(b) under an ATSO authorisation or letter of ATSO design approval; or
(c) in conjunction with type certification procedures for an aircraft, aircraft engine or propeller; or
(d) under Subpart 21.N; or
(da) in a manner prescribed by the Part 21 Manual of Standards; or
(e) in any other manner approved by CASA.
Source FARs section 21.305 modified.