Ham - Ksha

Ham -                                             Ksha
5 Letters of Great Emptiness - 6 Letters of Empty Potential
Here, Khedrupje only gives two points: that the letters "haṃ" and "kṣa" represent the five and six letters of great emptiness; "haṃ" indicating the awareness of great bliss and "kṣa" the secret lotus of Mahāmudrā. The two of these in inseperable union purify of obscurations all the six elements, and this is indicated by the five and six letters of great emptiness.

Much the same could be said of the two syllables "e" and "waṃ". These are usually depicted either side of the Kālacakra monogram.