Rectification of errors apparent on the face of record permits authorities to correct obvious errors with natural justice safeguards. Any authority issuing a decision, order, notice, certificate or other document may correct an error apparent on the face of record on its own motion or when notified by an officer or the affected person within a short period from issuance; clerical or arithmetical corrections from accidental slips are excepted from the outer time limit, and where rectification adversely affects a person the authority must follow the principles of natural justice.