Pāṇini sūtras

The affix ṭach comes after sakthi when preceded by uttara, mṛiga, and pûrva in a Tatpurusha compound, as well as when a thing is compared with it.

1. uttara+mṛga+pūrvātउत्तर+मृग+पूर्वात्

   Part	Lexeme	Sandhi form	Meaning	Stem + termination
   uउ	uttaraउत्तर	uttaraउत्तर	uttara [word]	uttarउत्तर् + plus aअ
   mम्	mṛgaमृग	mṛgaमृग	mṛga [word]मृग [wओर्द्]	mṛgमृग् + plus aअ
   pप्	pūrvaपूर्व	pūrvātपूर्वात्	pūrva [word]पूर्व [wओर्द्]	pūrvaपूर्व + plus tत्

2. caच

   Part	Lexeme	Sandhi form	Meaning	Stem
   cच्	caच	caच	besides	caच

3. sakthnaḥसक्थ्नः

   Part	Lexeme	Sandhi form	Meaning	Stem + termination
   sस्	sakthiसक्थि	sakthnaḥसक्थ्नः	sakthi [word]	sakthसक्थ् + plus naḥनः

Anuvṛtti

1. samāsa+antāḥसमास+अन्ताः 5·4·68

   Part	Lexeme	Sandhi form	Meaning	Stem + termination
   sस्	samāsaसमास	samāsaसमास	Sanskrit compound	samāsसमास् + plus aअ
   aअ	antaअन्त	antāḥअन्ताः	end	antअन्त् + plus āMआM

2. tatpuruṣasyaतत्पुरुषस्य 5·4·86

   Part	Lexeme	Sandhi form	Meaning	Stem + termination
   tत्	tatpuruṣaतत्पुरुष	tatpuruṣasyaतत्पुरुषस्य	tatpuruṣaतत्पुरुष	tatpuruṣतत्पुरुष् + plus asyaअस्य

3. ṭacटच् 5·4·91

   Part	Lexeme	Sandhi form	Meaning	Stem
   ṭट्	ṭacटच्	ṭacटच्	ṭacटच्	ṭacटच्

4. upamānātउपमानात् 5·4·97

   Part	Lexeme	Sandhi form	Meaning	Stem + termination
   uउ	upamānaउपमान	upamānātउपमानात्	comparison	upamānउपमान् + plus ātआत्