deriv SD cv (868) ashtadhyayi.com hei.de L 868 ETT STT a 8.2.42 ALPH OLDHOMEPAGE NEWHOMEPAGE

radAbhyAn niSThAto naH pUrvasya ca daH

रदाभ्यां निष्ठातो नः पूर्वस्य च दः ONPANINI 82042

After r र् d द्, replace /niSThA with n न्, and the d द् too.

So r र् + /kta turns into rN र्ण् —

zRR शॄ + /kta
→ zirta शिर्त by RRta::iddh...
→ zIrta शीर्त by halica
→ zIrna शीर्न by this rule
→ zIrNa शीर्ण with /Natvam
→ !**zIrNa- शीर्णॱ "broken"

sam सम् + kRR कॄ + /kta → !**saGkIrNa- संकीर्णॱ "narrow", same steps

And d द् + /kta turns into nn न्न् —

bhid भिद् + /kta
→ bhin भिन् + na न by this rule
→ !**bhinna- भिन्नॱ "untangled, cut, rent asunder"

sad सद् + /kta
→ san सन् + na न by this rule
→ !**sanna- सन्नॱ "set down"

And of course all nn न्न् are liable to get /Natvam —

/ni + **sanna- सन्नॱ
→ niSanna- निषन्नॱ because sad सद् is a Sa-root
→ niSaNna- निषण्नॱ with /Natvam, by aTkupvAGnumvy...
→ niSaNNa- निषण्णॱ by STunASTuH
→ !**niSaNNa- निषण्णॱ "seated; depressed"

Why does lU लू + /kta make **lUna- लूनॱ?

See lvAdibhyaH >>.