Every member of the Institute in practice shall, and any other member may, use the designation of a cost accountant and no member using such designation shall use any other description, whether in addition thereto or in substitution therefore:

Provided that nothing in this section shall be deemed to prohibit any such member from adding any other description or letters to his name, if entitled thereto, to indicate membership of such other Institute of accountancy, whether in India or elsewhere, as may be recognised in this behalf by the Council, or any other qualification that he may possess, or to prohibit a firm, all the partners of which are members of the Institute and in practice, from being known by its firm name as cost accountants.