In these lists of mountains in Ireland, those within Northern Ireland, or on the Republic of Ireland – United Kingdom border, are marked with an asterisk, while the rest are within the Republic of Ireland. Where mountains are ranked by height, the definition of the topographical prominence used to classify the mountain (e.g. the change in elevation required between neighbouring mountains), is noted. In British definitions, a height of is required for a mountain, whereas in Ireland, a lower threshold of is sometimes advocated. 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. While Irish mountains are ranked according to Irish classifications, they are also ranked on classifications that cover Britain and Ireland (e.g. Simms and P600s). Definitions General concepts There is no consensus on the definition of "mountain", but in Britain and Ireland it is often taken to be a summit over 2,000 ft, or more latterly, 600 m. There is less consensus about the topographical prominence requirement (e.g. the change in elevation required between neighbouring mountains), which can vary between . Prominence is even strongly debated regarding UIAA classification of Himalayan mountains. In the alps, the UIAA requires a prominence of over 30 m to be a "peak" and over 300 m to be a "mountain". The lowest threshold of prominence in Britain and Ireland is . The only definition in which prominence is not used, is where topographic isolation is used (e.g. the use of "sufficient separation" for Munros). Most Britain and Ireland definitions no longer categorise prominences below (e.g. no new Nuttalls and Vandeleur-Lynams), and peaks with a prominence between are now defined as tops rather than mountains (e.g. the 227 Munro Tops). In Ireland, a prominence threshold of is proposed for a mountain. Main classifications Other classifications The term Dillon is used to describe any of the 212 Irish summits in Paddy Dillon's well–regarded Irish 2010 climbing guidebook: