After a Pronominal aṅga (stem) ending in a , ī is substituted for the Nominative 1st-Case plural as,
Thus सर्वे (सर्व + ई), विश्वे, ये, के, ते ॥ Though सर्व + इ would have also given सर्वे, the long ई is taken for the sake of subsequent sutras, in forming त्रपुणी, जतुनी ॥,