 The height of a summit above its highest col (called the key col) is effectively a measure of a mountain's topographic prominence.Cols lie on the line of the watershed between two mountains, often on a prominent ridge or arête.For example, the highest col in Austria, the "Obere Glocknerscharte" ("Upper Glockner Col", ), lies between the Kleinglockner () and Großglockner () mountains, giving the Kleinglockner a minimum prominence of 17 metres.