v is optionally the substitute of the Particle u when it is preceded by may consonant (all consonants with the exception of the semi-vowels, sibilants, ha and ña) and is followed by a vowel.,
Thus शमु अस्तु वेदिः or शम्वस्तु वेदिः, तद् उ अस्य रेतः or तद्वस्य रेतः, किम् उ आवपनम् or किम्वावपनम् ॥ The उ is a Pragrihya by 1.1.14, and therefore would have remained unchanged, this ordains व् optionally. This व being considered asiddha, the म् is not changed to anusvara in किम्वावपनम्, शम्वस्तु &c, by 8.3.23.
When this उ is followed by इति, and preceded by a मय् consonant, then by (I. I. 17), it is optionally प्रगृह्य, and it may be replaced by ऊँ ॥ When it is not a pragrihya, then it is changed to व् by यणादेश (VI. I. 77), or to व् by the present sutra. In the case of यणादेश व्, there is anusvara by 8.3.23, as किंविति ॥ When it is a Pragrihya, then it is changed to व् by the present sutra as किम्विति or किमु इति ॥ So also with ऊँ substitute, where the व्ँ will be nasal : as किम्विँति, or ऊँ will remain unchanged, as किम् ऊँ इति ॥ Thus we have five forms with इति ॥,