This is supplementary/alternative to my previous idea.
Examining the internal waves of my presupposed "impulse," I realized some counts might mismatch Elliott's Law.
Instead, this move may form a corrective wave, e.g., complex correction (WXYXZ, Gray) or Diagonal Triangle (ABCDE, red; could be longer if with a thrust).
The chart would be self-explanatory, but the Triangle annotation is shifted for visibility.
In either scenario, the retracement in the fourth (corrective) wave is deeper than that of the impulse.
