The affix ṇini is added to the root in denoting agent, showing that there is some 'necessity' or 'indebtedness' or 'obligation' on the part of the agent in connection with the action denoted by the verb.,
Thus अवश्यं कारी 'must be done'. The compounding here takes place by 2.1.72. So also शतं दायी 'ought to be given a hundred'; सहस्रं दायी; निष्कं दायी &c.,