Commonly referred to as the NIAS (Non incident or accident statement) or NIS (Non incident statement), this is a letter which acts as a statement that a component, part or aircraft has not been involved in an “accident” or “incident” during a noted time scale of operation and is issued by a CAMO (Continued Airworthiness Management Organisation) typically.
The letter will state typically the period of operation that it covers along then with the operator details or owner details making the statement.
The specifics for the item covered should also be noted. This will differ a little depending on what the statement is for; for example, an aircraft NIAS would note the Aircraft Registration, MSN (Manufacturers Serial Number), Total Airframe Hours & Cycles at the time of the statement along then with the PN (Part Number) or SN (Serial Number) for major components like the engines.