The document describes the Diedric system for representing 3D figures using orthogonal projections. It explains that the system projects a figure onto perpendicular planes to show the front, left profile, and floor views. It provides instructions for drawing the axes and individual views of a figure, and notes conventions like using the same scale across views and indicating hidden lines with dashed lines. The document includes examples of drawing different views of objects and concludes with an exercise showing views of various figures.