Mapping of the probability vector onto an equilateral triangle. Each QuartOP is represented as a probability vector P inside an equilateral triangle. The position of P is determined by the barycentric coordinates (p1, p2, p3), which correspond to the posterior probabilities or bootstrap support values of the three possible tree topologies. The vertices of the triangle T1, T2 and T3 represent the three possible unrooted tree topologies. Geometrically, each of the coordinates (p1, p2, p3) equals the distance between P and the side of the triangle opposite the corresponding vertex. Points closer to a vertex Ti have a larger corresponding probability pi and represent a more probable tree topology than the two alternatives. All the points are classified by their position in one of three zones: "total" zone, "90%" zone and "99%" zone, which are depicted schematically and not drawn to scale. In this diagram, point P corresponds to a dataset which has highest probability for the topology T3, but the probability is below 90%, so the point P is located in the "total" zone, but not in the 99% or 90% zone. Figure adapted from .