Bhadrasana - Grace and Skill
Bhadra भद्र : connotation of auspicious, skilful, beautiful, graceful [See Spokensanskrit]. To make it more complicated, the Hatha Yoga Pradipika states that it also goes by the name of Goraksasana. English terms for this position include the "Butterfly", "Locked Lotus", "Gentle", and the "Throne."
"Place the heels on either side of the seam of the Perineum, keeping the left heel on the left side and the right one on the right side, holding the feet firmly joined to one another with both the hands. This Bhadrasana is the destroyer of all diseases.
The expert Yogis call this Goraksa asana. By sitting with this asana, the Yogi gets rid of fatigue." Hatha Yoga Pradipika, sloka 55-56-57
Sitting on the ground, bring your feet to the perineum with the soles facing and touching one another. Hold the feet with both hands drawing the heels towards the pelvis and moving the knees to the ground. The spine is vertical
The figure below shows one of the several variations involving the rotation of the ankle joint.