A long vowel is substituted for the final vowel of the preceding word, before the verbs 1. nah 2. vṛt 3. vṛṣ 4. vyadh 5. ruc 6. sah and 7. tan when these roots take the affix kvi,
Thus उपानह् (उपानत् Nominative Singular), so also, परीणत्, नीवृत्, उपावृत्, (with vrt) प्रावृट्, उपावृट्, (with vrsh) ममावित्, हृदयावित्, श्वावित् (with vyadh) नीरुक्, अभीरुक्, (with ruch) ऋताषट्, (with sah) तरीतट् (with tan). The nasal is elided after गम् before क्वि 6.4.40, by an extension of that rule, it is elided after तम् also. Why do we say when क्वि follows? Observe परिणहनम् ॥,