The affix ṅīp is added, in forming the feminine to the stems that end in the syllable van , and r is the substitute of the final such syllable.,
Thus धीवन् (Unadi IV. 115) f. धीवरी 'a female artisan'; पीवन् f. पीवरी 'a young woman, a stout woman', शर्वन् f. शर्वरी 'night' (शृ + वनिप् 3.2.75) lit. that which destroys light. So also परलोकदृश्वरी ॥
Words ending in वन् are formed by the affixes ङ्वनिप्, 3.2.103 क्वनिप् and वनिप् 3.2.74 These words end in न् and consequently would have taken ङीप् even by 4.1.5; the necessity of the present sutra arose in order to teach the change of न् into र् in case of words ending in वन् ॥
Vart:- If the affix वन् is ordained to be added to a word ending in हश्, (a letter of हश् pratyahara), and is thus immediately preceded by a soft consonant then this rule does not apply, that is to say, there is neither the application of the affix ङीप् nor the change of म् into र् ॥ Thus सहयुध्वन् is both masculine and feminine as, सहयुध्वा ब्राह्मणः or ब्राह्मणी 'a Brahman brother or sister in arms'. In शर्वन् the वन् is preceded by र् which is a letter of हश् class, but as वन् is not ordained to be applied to शर् but to शृ, and we get the र् indirectly by guna, the vartika does not apply to such a case. Hence शर्वरी ॥,