Not every move is an . Pullbacks against the trend are called corrections and usually have three parts. The main patterns: (5-3-5, sharp), (3-3-5, more sideways), (five three-part waves A to E) and such as W-X-Y. Wave 2 is often a zigzag, wave 4 then more likely a flat or triangle ().
Zigzag or flat?
In a zigzag, wave A is an impulse of five parts; B usually retraces 38.2–78.6% of A, C is often as long as A. In a flat, A has three parts, and B comes back to at least 88.7% of A. If B rises above the start of A, it is an expanded flat – the most common form. If C then ends before the end of A, it is a rare running flat.
Triangle and combination
A triangle has five waves A to E. In a contracting triangle each is at least 23.6% and usually at most 88.7% as long as the one before, A is the longest; in the rare expanding one 100–261.8% each, A the shortest. It appears in wave 4, B or X, rarely in Y or Z, never in wave 2. Combinations string three-part patterns together (W-X-Y, W-X-Y-X-Z); X retraces at most 88.7% of W.
Where counting errors happen
Most errors happen in corrections: wave B is taken for a new impulse, a flat for a zigzag, a combination for a simple ABC. Our rule does not recognize these patterns – it only checks how deep wave 2 retraces. So it does not rule out a triangle in wave 2 either.