aṅ is optionally the substitute of cli after that root which has an indicatory ir , when the parasmaipada terminations are used.,
Thus from भिदिर् (भिद) 'to divide', we derive अभिदत् or अभैत्सीत्. But we have अभित्त in the Atmanepada. So from छिदिर् — अच्छिदत् or अच्छैत्सीत्.,