the iaru rules go into great detail about certain procedures that are unique to international championships events. not every ardf competition follows all of these rules. common variations to the generally accepted rules exist at local events. most smaller events do not have large juries or on-course referees. some events will use simpler start procedures, such as using only one starting corridor instead of two. ardf events on the two meter band in north america sometimes use frequency modulation instead of amplitude modulation for the transmission of the morse code identifications.