It is necessary for user to specify on a map a basic line and point object from which the normal to basis will be dropped. The choice of a basic line can be carried out by two ways: by the consecutive indication of two point objects (the first point - the initial point, the second point - a terminal point) and by a choice of a piece of the metrics of linear or polygon object. This task is return task to a method of normals. Coordinates of a picket point are calculated as a result of a finding of a crossing's point of basis of construction and a normal dropped on it from already existing point of a map.
