Amendment 21-38 of Part 21 was published May 26, 1972. This was the next rule change to affect PMAs. This rule eliminated the incorporation by reference of type certification requirements in favor of PMA-specific data submission requirements. This change established the separate process and separate requirements for data that must be submitted by an applicant for a PMA (prior to this there was no explicit distinction between the application data requirements for type certificated products and the data requirements for PMAed articles).