deriv SD cv (371) ashtadhyayi.com hei.de L 371 ETT STT a 6.4.10 ALPH OLDHOMEPAGE NEWHOMEPAGE

sAnta;mahatas saMyogasya

सान्तॱमहतः संयोगस्य ONPANINI 64010

(Before a strong that is not the /sambuddhi, lengthen the last vowel) of clusterending s स्-enders and mahat- महत्.

These bases end in a cluster when previous rules give them /num.

Example. The base zreyasu has /udit because it is formed with Iyasun, so it gets /num when strong by ugidacAMs..., then it ends in the cluster ns न्स् —

zreyasu- m + /su
→ zreyanss श्रेयन्ःस्, with /num by ugidacAMs...
→ zreyAnss श्रेयान्ःस् by this rule
→ **zreyAn श्रेयान् m "better"

cakSus चक्षुस् + /zi
→ cakSus चक्षुस् + /num + /zi by napuMsakasy...
→ cakSuns चक्षुन्स् + /zi by midacontyAtp...
→ cakSUns चक्षून्स् + i इ by this rule
→ cakSUMs चक्षूंस् + i इ by nazcApadAnt...
→ cakSUMSi चक्षूंषि (by numvisarjan..., there is /Satvam even though /M comes in between)
→ !**cakSUMSi चक्षूंषि "3+ eyes".

**manAMsi मनांसि

I don't understand the wording of the original sUtra.

The literal translation is "(replace with a long that nexttolast vowel) of a clusterending mahat or a clusterending s-ender". It is a bit weird that the vowel before nt न्त् or ns न्स् is called a nexttolast, but it sort of makes sense because it was called a nexttolast before the /num was added.