
This is the classical "Horse Stance". The thighs must be parallel to the floor and knees pushed out and lined up above the toes (never push your knees in on a horse). The toes must also be pointed straight and kept flat on the floor. Your stance should look squared (boxed) when looking at it from a frontal view. Hips tucked in and chest out.
Some Wu Shu guys stick their butt out to help emphasize their chest out (military) posture. Never stick your butt out in your horse stance! That takes away from it's being firm and decreases it's strength and makes it flimsy.