The affixes āya and those that follow it i.e. āya , īyaṅ and ṇiṅ are optionally added, when it is desired to express one's self with an ārdhadhātuka affix.,
Thus ता 3rd. sing. of the Future is an ardhadhatuka affix. It is optional to retain the aya of gopaya before this affix. So we have गोपायिता or गोप्ता 'he will protect'. So also अर्तिता or ऋतीयिता; कमिता or कामयिता.
But for this sutra, the affixes आय &c. would have come always even when ardhadhatuka affixes were to be applied. This makes it optional. Therefore proper ardhadhatuka affixes should be applied when we retain आय &c. and when we do not retain them. Thus the ardhadhatuka क्तिन् 3.3.95 will be employed in forming the feminine noun from the simple root, but the ardhadhatuka अ 3.3.102 will be employed in forming the feminine when आय &c. are retained. Thus गुप्तिः or गोपावा.,