Pāṇini sūtras

After the verbs vṛit to exist &c., Parasmaipada is optionally employed when the affixes sya (Future and conditional) and san (Desiderative) follow.

German An vṛt u. s. w. im Futurum, Conditionalis und Desiderativ. (92)

1. vṛtbhyaḥवृत्भ्यः

   Part	Lexeme	Sandhi form	Meaning	Stem + termination
   vव्	vṛtवृत्	vṛtbhyaḥवृत्भ्यः	vṛtवृत्	vṛtवृत् + plus bhyaḥभ्यः

2. sya+sanoḥस्य+सनोः

   Part	Lexeme	Sandhi form	Meaning	Stem + termination
   sस्	syaस्य	syaस्य	syaस्य	syस्य् + plus aअ
   sस्	sanसन्	sanoḥसनोः	desiderative ending	sanसन् + plus oḥओः

Anuvṛtti

1. parasmaipadamपरस्मैपदम् 1·3·78

   Part	Lexeme	Sandhi form	Meaning	Stem + termination
   pप्	parasmaipadaपरस्मैपद	parasmaipadamपरस्मैपदम्	active voice	parasmaipadपरस्मैपद् + plus amअम्

2. vāवा 1·3·90

   Part	Lexeme	Sandhi form	Meaning	Stem
   vव्	vāवा	vāवा	optionally	vāवा