The affix lyuṭ is added to the root when the name of an action is expressed, in the neuter gender.,
Thus हसनं छात्रस्य 'the laughter of the student'; शोभनं 'beauty'; जल्पनं 'speech'; शयनं 'sleep'; आसनम् 'seat'.
The separation of this sutra from the last, in which it might well have been included, is for the sake of the subsequent aphorisms, in which the anuvritti of lyut only runs, and not that of क्त ।,