The peak must have a prominence of at least 200 feet. Prominence is the vertical distance a given summit rises above the lowest col/saddle (called a key col) connecting it to a higher summit (called a line parent). The line parent is defined as the closest higher peak to a given summit, following ridge lines past the key col. This site uses clean prominence for calculating prominences; using the highest contour line at the key col, and the lowest contour line for peak closed contours. When calculating prominence, except for Ishpatina Ridge – Tower Peak, only peaks residing in Ontario are considered as candidates for line parents. See here for more about prominence.