The affix ṇamul comes after the verb kaṣ 'to rub' when the words nimūla and samūla are compounded with it in the Accusative -2nd case.,
Thus निमूलकाषं कषति 'he scrapes down to the roots'; समूलकाषं कषति 'he scrapes up to the roots'. In fact, the gerund of the root and the root itself denote the same thing; the whole sentence निमूलकाषङ्कषति being equal to निमूलं कषति. From this sutra up to sutra 3.4.46, the subsequent verb governing the previous word, must be derived from the same root from which the gerund is derived; see sutra 3.4.46.,