In forming the feminine with the affix ṅīp the letter ai having udātta accent is the substitute of the finals 1. vṛṣākapi 2. agni 3. kusati and 3. kusīda ,
The words वृषाकपि and कुसीद have udatta accent on the middle vowel (Phit Su II. 19), the feminine of these has udatta, however, on the final. The words 'agni' and the rest have the udatta on the final (Phit su 1. 1), their substitute ऐ will necessarily be udatta, by the rule of sthanivat bhava, even if the present sutra had not explicitly declared it to be so. Thus वृषाकपायी (Rig Veda X. 86. 13) 'the wife of Vrishakapi', अग्नायी, (Rig Ved. I. 22. 12) the wife of 'Agni', कुसितायी 'wife of Kusita', कुसिदायी 'the wife of Kusidai'. The present rule only applies when the sense of the feminine word is that of 'wife of'. Otherwise we have वृषाकपिः स्त्री 'the women Vrishakapi' and not वृषाकपायी ॥ For the accent of the word वृष, See 6.1.203.,