Long ī is substituted for the final of a or ā of a Nominal stem, before the Adverbial affix cvi -- abhūtatadbhāve kṛbhvastiyoge sampadyakartari cviḥ [[5.4.50]],
As शुक्ली करोति, शुक्ली भवति, शुक्ली स्यात् ॥ खट्वी करोति, खट्वी भवति and खट्वी स्यात् ॥,