Pāṇini sūtras

After a word denoting direction, the first vowel of the name of a village or city in the land of the eastern people, gets the Vṛiddhi before a Taddhita affix having an indicatory ñ, ṇ or k

1. prācāmप्राचाम्

   Part	Lexeme	Sandhi form	Meaning	Stem + termination
   pप्	prāñcप्राञ्च्	prācāmप्राचाम्	eastern	prप्र् + plus ācआच्

2. grāma+nagarāṇāmग्राम+नगराणाम्

   Part	Lexeme	Sandhi form	Meaning	Stem + termination
   gग्	grāmaग्राम	grāmaग्राम	village	grāmग्राम् + plus aअ
   nन्	nagaraनगर	nagarāṇāmनगराणाम्	town	nagarनगर् + plus āMआM

Anuvṛtti

1. uttara+padasyaउत्तर+पदस्य 7·3·10

   Part	Lexeme	Sandhi form	Meaning	Stem + termination
   uउ	uttaraउत्तर	uttaraउत्तर	following	uttarउत्तर् + plus aअ
   pप्	padaपद	padasyaपदस्य	word	padपद् + plus asyaअस्य

2. diśaḥदिशः 7·3·13

   Part	Lexeme	Sandhi form	Meaning	Stem + termination
   dद्	diśदिश्	diśaḥदिशः	direction	diśदिश् + plus aḥअः