A peak is a fold. Both panels have to meet.

Climb is one panel. Descent is the other. If they do not meet over the hole, the fold is a brochure, not a book.

People talk about "higher" as if it were a blessing. Higher that does not fold back down in mist is a clip. Lower that still folds clean in still air can be the hold gate. Dax will say which panel failed. He will not sell you a taller brochure.