deriv LSK ETT STT aSTA ALPH OLDHOMEPAGE NEWHOMEPAGE
This word is used to stop the inheritance of words meaning "optionally".
E.g., sUtra sa::uttamasya erases a certain s स् of the /leT optionally. Then next sUtra nityaGGitaH erases the s स् of the /liG /laG /luG /lRG compulsorily. If the latter sUtra did not have the word /nityam, it would inherit the "optionally" word from the former.