/utsarga / उत्सर्ग

/utsarga means general rule, and /apavAda means special rule, or exception.

/apavAda rules debar /utsarga rules. When more specific rules conflict with more general rules, the specific wins, because otherwise the specific would be useless.

Example. The general rule kharavasAn... teaches the replacing of all r र् with H ः before all s स्, including the s स् of /sup', as in manaru मनरु + /sup' → manaHsu and gIr गीर् + /sup' → gIHsu. And then the more specific rule rossupi teaches that the r र् of gIr- गीर् should stay unchanged before /sup', so gIr गीर् + /sup' → gIrsu. Whenever these two rules contradict each other, rossupi must win, because if kharavasAn... won, rossupi would never ever work and would be completely useless.