The manufacturer shall ensure that changes to documents are reviewed and approved either by the original approving functionary or another designated functionary which has access to pertinent background information upon which to base its decisions. The manufacturer shall define the period for which at least one copy of obsolete controlled documents shall be retained. This period shall ensure that documents to which medical devices or in vitro diagnostic medical devices have been manufactured and tested are retained for at least one year after the date of expiry of the medical device or in vitro diagnostic medical devices as defined by the manufacturer.