deriv LSK ETT STT aSTA ALPH OLDHOMEPAGE NEWHOMEPAGE

/etad- / एतद्

The pronoun nounbase /etad- means "this". To add a /sup to it, first add the /sup after /tad-, and then attach e ए in front —

/etad- + /su
→ e ए + () tad तद् n + /su )
→ e ए + tad तद् n + /su
→ !**etad एतद् n "this"

or also

!**etat एतत् n "this", normalizing

When the noun from /tad- starts with s स्, we get /Satvam after e ए —

e ए + tad तद् m + /su → e ए + **sas सस् → eSas एषस् with /Satvam

e ए + tad तद् f + /su → e ए + **sA सा → eSA एषा with /Satvam

This is not how /pANini does it.

True.