The affix phak comes in the sense of a gotra (Patronymic) descendant, optionally after the words 1. droṇa 2. parvata and 3. jīvanta,
This debars इञ् of 4.1.95. Thus द्रौणायनः or द्रौणिः, पार्वतायनः or पार्वतिः जैवन्तायनः or जैवन्तिः ॥
The affix फक् is employed in denoting a remote (gotra) offspring and not an immediate descendant or son. How is then अश्वत्थामा the son of Drona, called द्रौणायनः and not द्रौणिः in the phrase \अश्वत्थामा द्रौणायनः\? The द्रोण here does not refer to the Drona of the Mahabharat, but to some ancient founder of a clan of that name, and his descendants were called द्रौणायनाः ॥ In modern times, by an easy error, Asvatthama was called Draunayana, owing to the similarity of sounds.,