The guideline of alternation states that if wave two of an impulse is a sharp retracement, expect wave four to be a sideways correction, and vice versa. Figure 22 shows the most characteristic breakdowns of impulse waves, both up and down. Sharp corrections never include a new price extreme, i.e., one that lies beyond the orthodox end of the preceding impulse wave. They are almost always zigzag (single, double or triple); occasionally they are double threes that begin with a zigzag. Sideways corrections include flats, triangles, and double and triple corrections. They usually include a new price extreme, i.e., one that lies beyond the orthodox end of the preceding impulse wave.