on back
knees bent
feet flat on floor
hands at side
motionless

(position to be sexually used)

Kajira of Gor, page 422

Prone on the back, knees bent with feet flat on the ground, hands at the side, and motionless.

"On your back," he said, "knees raised, heels on the floor." I then lay before him, in a standard, supine capture position.