Pāṇini sūtras

The substitution of sa for samāna is optional before udara when the affix yat is added to it.

1. vibhāṣā+udareविभाषा+उदरे

   Part	Lexeme	Sandhi form	Meaning	Stem + termination
   vव्	vibhāṣविभाष्	vibhāṣāविभाषा	option	vibhāṣविभाष् + plus āआ
   uउ	udaraउदर	udareउदरे	udara [word]	udarउदर् + plus eए

Anuvṛtti

1. uttara+padeउत्तर+पदे 6·3·1

   Part	Lexeme	Sandhi form	Meaning	Stem + termination
   uउ	uttaraउत्तर	uttaraउत्तर	last	uttarउत्तर् + plus aअ
   pप्	padaपद	padeपदे	word	padपद् + plus eए

2. saḥसः 6·3·78

   Part	Lexeme	Sandhi form	Meaning	Stem + termination
   sस्	saस	saḥसः	sa [word]	sस् + plus aḥअः

3. samānasyaसमानस्य 6·3·84

   Part	Lexeme	Sandhi form	Meaning	Stem + termination
   sस्	samānaसमान	samānasyaसमानस्य	samāna [word]समान [wओर्द्]	samānसमान् + plus asyaअस्य

4. yeये 6·3·87

   Part	Lexeme	Sandhi form	Meaning	Stem + termination
   yय्	yaय	yeये	yaय	yय् + plus eए