DTM Slopes and retaining walls
Classically - The upper part of the retaining wall is marked with a red line. The task is to draw the lower part of the wall, to do it you would have to get to the red line and get down to the ground by every vertex.
Applying FLAT - After drawing the upper part with the red line and getting down to the ground level you can easily draw the lower part of the wall with accuracy of the route and without any additional operation.
See:
FLAT