Pāṇini sūtras

s is the substitute of a visarga before an affix beginning with a hard guttural or labial.

German Vor einem mit einem tonlosen Guttural oder Labial anlautenden Suffix tritt s an die Stelle des Visarjanīya. (38)

1. saḥसः

   Part	Lexeme	Sandhi form	Meaning	Stem + termination
   sस्	saस	saḥसः	sakāraसकार	sस् + plus aḥअः

2. a+pada+ādauअ+पद+आदौ

   Part	Lexeme	Sandhi form	Meaning	Stem + termination
   aअ	aअ	aअ	not	aअ
   pप्	padaपद	padaपद	word	padपद् + plus aअ
   āआ	ādiआदि	ādauआदौ	first syllable	ādआद् + plus auऔ

Anuvṛtti

1. visarjanīyasyaविसर्जनीयस्य 8·3·34

   Part	Lexeme	Sandhi form	Meaning	Stem + termination
   vव्	visarjanīyaविसर्जनीय	visarjanīyasyaविसर्जनीयस्य	visarga	visarjanīyविसर्जनीय् + plus asyaअस्य

2. ku+pvoḥकु+प्वोः 8·3·37

   Part	Lexeme	Sandhi form	Meaning	Stem + termination
   kक्	kuकु	kuकु	guttural	kक् + plus uउ
   pप्	puपु	pvoḥप्वोः	labial consonant	pप् + plus voḥवोः