Rectification of record errors: authorities may correct apparent mistakes within prescribed timeframes, with exceptions and natural justice safeguards. Section 161 authorises any issuing authority to rectify errors apparent on the face of a decision, order, notice, certificate or other document on its own motion or on notice from an officer or the affected person, subject to prescribed time limits; an exception to the outer time limit applies for clerical or arithmetical errors from accidental slips or omissions, and any rectification that adversely affects a person must follow the principles of natural justice.