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, m (AA)), lies between the Kleinglockner ( m above sea level (AA)) and Großglockner ( m above sea level (AA)) mountains, giving the Kleinglockner a minimum prominence of 17 metres.