Pāṇini sūtras

And the affix tasi comes optionally after a word ending in the third case-affix, when such word is joined to the verb “hûya”, or the noun “pâpa”; not denoting an agent.

1. hīyamāna+pāpa+yogātहीयमान+पाप+योगात्

   Part	Lexeme	Sandhi form	Meaning	Stem + termination
   hह्	hīyamānaहीयमान	hīyamānaहीयमान	hāहा	hīyamānहीयमान् + plus aअ
   pप्	pāpaपाप	pāpaपाप	pāpa [word]पाप [wओर्द्]	pāpपाप् + plus aअ
   yय्	yogaयोग	yogātयोगात्	connection	yogयोग् + plus ātआत्

2. caच

   Part	Lexeme	Sandhi form	Meaning	Stem
   cच्	caच	caच	besides	caच

Anuvṛtti

1. anyatarasyāmअन्यतरस्याम् 5·4·42

   Part	Lexeme	Sandhi form	Meaning	Stem + termination
   aअ	anyataraअन्यतर	anyatarasyāmअन्यतरस्याम्	optional	anyataraअन्यतर + plus syāmस्याम्

2. tasiḥतसिः 5·4·44

   Part	Lexeme	Sandhi form	Meaning	Stem + termination
   tत्	tasiतसि	tasiḥतसिः	tasतस्	tasतस् + plus iḥइः

3. tṛtīyāyāḥतृतीयायाः 5·4·46

   Part	Lexeme	Sandhi form	Meaning	Stem + termination
   tत्	tṛtīyतृतीय्	tṛtīyāyāḥतृतीयायाः	instrumental	tṛtīyतृतीय् + plus āyआय्