What conventional signs are used to show the relief on the terrain plans?

The relief on terrain plans and maps is depicted using linear conventional signs, namely, using contours and semi-horizontals. A horizontal is an imaginary line passing through points with the same elevation. The height of the points through which the horizontal passes is necessarily signed on plans and maps. The direction towards catchments is indicated by bergstrokes. The contours are drawn through a distance equal to the accepted height of the relief section. Dotted semi-horizontals can be drawn between the horizontals.