Both of these are done with the line head tilted at a steep angle Scalping is removing top growth leaving the earth bear.
Edging is trimming the grass back where it has spread over a sidewalk or drive way. During both edging and scalping, hold the unit a steep angle and in a position where the debris, and any dislodging dirt and stones, will not come back towards you even if it ricochets off
the hard surface. Although the picture shows how to edge and scalp every operator must find for himself the angles which suits his body size and cutting situation.