Finally pt can be defined on morphisms of Frm rather canonically by defining, for a frame morphism "g" from "L" to "M", pt("g"): pt("M") → pt("L") as pt("g")("p") = "p" o "g". In words, we obtain a morphism from "L" to 2 (a point of "L") by applying the morphism "g" to get from "L" to "M" before applying the morphism "p" that maps from "M" to 2. Again, this can be formalized using the other descriptions of points of a locale as well – for example just calculate ("p" o "g") −1(0).