The Eliteserien, until 1991 known as the 1. divisjon and between 1991 and 2016 known as Tippeligaen, has employed a system of play-off qualification to determine promotion and relegation with the 1. divisjon (until 1991 the 2. divisjon). Various varieties have been in place since the system was introduced at the end of the 1972 season, but only one team has been promoted per year. The play-offs have always supplemented a system of direct promotion and relegation of two teams. The play-offs have been wavered twice, in the 1994 and 2011 seasons, when the top league was expanded to fourteen and sixteen teams, respectively.