The affix ṅīṣ is used in the feminine according to the opinion of the Eastern Grammarians after the word śoṇa,
Thus शोणी or शोणा वडवा 'a red or bay mare'. By Phit Sutra II. 10 referred to already in 4.1.39 the udatta in शोणा falls on the first syllable, and by 4.1.40 it would have taken ङीष् always; but the present sutra makes a niyama rule and restricts the application of ङीष् according to the opinion of Eastern Grammarians only, and not of others.,