पूङः क्त्वा च

The word 'optionally' of the previous sutra 1.2.21 does not govern this sutra, because the word 'optionally' has been again used in the next sutra 1.2.23; of which there would have been no necessity had the word 'optionally' governing force in this sutra, for then this would have also governed the next sutra. The anuvritti of न सेट् however is to be read in this sutra.

By rule 7.2.51, after the verb पू the affixes Nishtha and क्त्वा ktva take the intermediate इ. So that क्त्वा ktva being set (by virtue of Rule 7.2.51) would have been non-kit by Rule 18; and it might be asked what is the necessity of repeating it in this sutra, when sutra 1.2.18 comprised the case. The reason of this repetition is that by mentioning क्त्वा ktva in this sutra, it has governing force over the succeeding sutras. As पवितः, पवितवान्.,