Pāṇini sūtras

The affix u comes after the roots of the Tanâdi class and after the verb kṛ ‘to make’ when a sârvadhâtuka affix follows, signifying the agent.

1. tan+ādi+kṛñbhyaḥतन्+आदि+कृञ्भ्यः

   Part	Lexeme	Sandhi form	Meaning	Stem + termination
   tत्	tanतन्	tanतन्	tanतन्	tanतन्
   āआ	ādiआदि	ādiआदि	etc.	ādआद् + plus iइ
   kक्	kṛñकृञ्	kṛñbhyaḥकृञ्भ्यः	kṛकृ	kṛñकृञ् + plus bhyaḥभ्यः

2. usउस्

   Part	Lexeme	Sandhi form	Meaning	Stem
   uउ	usउस्	usउस्	usउस्	usउस्

Anuvṛtti

1. dhātoḥधातोः 3·1·22

   Part	Lexeme	Sandhi form	Meaning	Stem + termination
   dद्	dhātuधातु	dhātoḥधातोः	Sanskrit verbal root	dhātधात् + plus oḥओः

2. sārvadhātukeसार्वधातुके 3·1·67

   Part	Lexeme	Sandhi form	Meaning	Stem + termination
   sस्	sārvadhātuसार्वधातु	sārvadhātukeसार्वधातुके	sārvadhātukaसार्वधातुक	sārvadhātukसार्वधातुक् + plus eए

3. kartariकर्तरि 3·1·68

   Part	Lexeme	Sandhi form	Meaning	Stem + termination
   kक्	kartṛकर्तृ	kartariकर्तरि	agens	kartकर्त् + plus ariअरि