Reference of classification and posture, Here is my Iyengar classifications and posture Dictionary document, with credit to the Iyengar Yoga UK Schools, my teachers alive and dead. Readers of ‘Light on Yoga’ may find it interesting to see the whole book put into Iyengars perceived difficulty order. Iyengar developed this according to his own/ Indian ability, therefore placing some postures of great difficulty to westerners in a lower classification of his own, for example full lotus posture is only 4/ 60.