Optionally when va or ma follow, the na of han is changed to ṇa , when preceded by an upasarga competent to cause the change.,
Thus प्रहण्वः, परिहण्वः, or प्रहन्वः and परिहन्वः, प्रहण्मः or प्रहन्मः परिहण्मः or परिहन्मः ॥
This sutra enjoins an option in certain cases, where it would have been obligatory by the last rule.,