The affix ṅīp is used in denoting the feminine after a prātipadika (Nominal Stem) ending in yañ -- gargādibhyo yañ [[4.1.105]].,
Thus गार्ग्य + ङीप् = गार्ग्य + ई 6.4.148 = गार्ग् + ई 6.4.150 = गार्गी 'a female descendant of Garga'; so also वात्सी ॥
Vart:- This rule applies when the affix यञ् denotes a descendant, and not otherwise. Therefore ई will not be applied to form the feminine of द्वैप्य of द्वीप् + यञ् 4.3.10. Its feminine will be द्वैप्या 'a living on or relating to an island'.
The separation of this sutra from the last, (for the affix यञ् could well have been included in the same), is for the sake of the subsequent aphorisms; in which the anuvritti of यञ् only runs and not of others.,