The lowest minimum prominence threshold of any definition of an Irish mountain is (e.g. the Vandeleur-Lynam), however most definitions, including the International Climbing and Mountaineering Federation (UIAA) criteria, do not consider prominences below as being mountains (e.g. must at least be an Arderin or a Hewitt). Many British definitions consider a peak with a prominence below , as being a top, and not a mountain (e.g. must be a Marilyn). A widely used definition of an Irish mountain requires a minimum prominence of (e.g. a HuMP), and is the basis for the 100 Highest Irish Mountains.