Pāṇini sūtras

And the affix laṅ comes after a verb when the particles ha and śaśvat are in connection with it, and when the verb denotes past action unperceived by the speaker, and before the commencement of the current day.

1. ha+śaśvatoḥह+शश्वतोः

   Part	Lexeme	Sandhi form	Meaning	Stem + termination
   hह्	haह	haह	ha [word]	haह
   śश्	śaśvatशश्वत्	śaśvatoḥशश्वतोः	śaśvat [word]शश्वत् [wओर्द्]	śaśvatशश्वत् + plus oḥओः

2. laṅलङ्

   Part	Lexeme	Sandhi form	Meaning	Stem
   lल्	laṅलङ्	laṅलङ्	imperfect (past)	laṅलङ्

3. caच

   Part	Lexeme	Sandhi form	Meaning	Stem
   cच्	caच	caच	and	caच

Anuvṛtti

1. an+adyataneअन्+अद्यतने 3·2·111

   Part	Lexeme	Sandhi form	Meaning	Stem + termination
   aअ	naन	anअन्	not	naन
   aअ	adyatanaअद्यतन	adyataneअद्यतने	today	adyatanअद्यतन् + plus eए

2. liṭलिट् 3·2·115

   Part	Lexeme	Sandhi form	Meaning	Stem
   lल्	liṭलिट्	liṭलिट्	perfect	liṭलिट्