Pāṇini sūtras

The u is the substitute of ru (the r substitute of s VIII.2.66) when it is followed by a soft consonant and preceded by an apluta short a

German Für ein solches aus s entstandenes r wird nach a auch vor tönenden Consonanten u substituirt. (114)

1. ha+śiह+शि

   Part	Lexeme	Sandhi form	Meaning	Stem + termination
   hह्	haह	haह	hakāraहकार	hह् + plus aअ
   śश्	śश्	śiशि	ŚŚ	śश् + plus iइ

2. caच

   Part	Lexeme	Sandhi form	Meaning	Stem
   cच्	caच	caच	besides	caच

Anuvṛtti

1. saṃhitāyāmसंहितायाम् 6·1·72

   Part	Lexeme	Sandhi form	Meaning	Stem + termination
   sस्	saṃhitāसंहिता	saṃhitāyāmसंहितायाम्	continuous speech	saṃhitसंहित् + plus āyआय्

2. ya+ṇ+a+ciय+ण्+अ+चि 6·1·77

   Part	Lexeme	Sandhi form	Meaning	Stem + termination
   aअ	aअ	aअ	akāraअकार	aअ
   cच्	cच्	ciचि	CC	cच् + plus iइ

3. e+ṅaḥए+ङः 6·1·109

   Part	Lexeme	Sandhi form	Meaning	Stem + termination
   eए	eए	eए	ekāraएकार	eए
   ṅङ्	ṅङ्	ṅaḥङः	NaNअ	ṅङ् + plus aḥअः

4. u+tउ+त् 6·1·111

   Part	Lexeme	Sandhi form	Meaning	Stem
   uउ	uउ	uउ	ukāraउकार	uउ
   tत्	tत्	tत्	TT	tत्

5. roḥरोः 6·1·113

   Part	Lexeme	Sandhi form	Meaning	Stem + termination
   rर्	ruरु	roḥरोः	ruरु	rर् + plus oḥओः