Muybridge horse · sprite plates

Stage · scrolling ground at the gait's own speed

Plate · the cycle laid out as Muybridge printed it (current frame boxed)

Gait diagram · stance bars per leg (Hildebrand), playhead = current frame

Near side = right legs (the sprite faces right, as Sallie Gardner ran). A bar is a hoof on the ground; gaps between all four bars are the "unsupported transit" Stanford bet on.