Sur le cou-de-pied is a ballet term meaning “on the ‘neck’ of the foot.” This term is for a position of the foot, not an actual step. The position of sur le cou-de-pied is when the working foot is placed on the other leg between the base of the calf muscle and the top of the ankle.
In Vaganova technique, sue le cou-de-pied is taught in two ways: basic and wrapped.
In the basic sur le cou-de-pied position to the front, the small toes of the pointed foot rest in the cou-de-pied position with the entire foot in front of the standing leg. The same idea holds true for sur le cou-de-pied to the back, or derriére, where the whole pointed foot is behind the standing leg, but now the big toe is pressing forward from the back.
In the wrapped sur le cou-de-pied position, the heel is placed in front of the standing leg, while the sole of the pointed foot is placed “wrapping” around the leg so that the toes are behind the leg and ankle of the standing leg.