Letter” are the same thing. Cover Letter for Original DMFs Cover Letter for Subsequent Amendments and Annual Reports (Not applicable to Holder Transfer, New Holder Acceptance, Holder Name Change, Letter of Authorization, and Closure Requests) Cover Letter for Reactivation of a Closed Drug Master File The following Letters do not require a Cover Letter Holder Transfer New Holder Acceptance Holder Name Change Letter of Authorization Closure Request Withdrawal of Authorization References External links FDA: Guideline for drug master files Third Party Manufacturing in Pharma 2022 Intellectual property law Pharmaceutical industry Food and Drug Administration American medical research Drug safety Experimental drugs United States federal health legislation Biotechnology products