The registrar may order the register to be rectified by the making, amendment or deletion of any entry therein, and such order may be made either on a request in the prescribed manner or without such request: Provided that where the registrar intends to make an order otherwise than upon a request, he shall give notice of his intention to do so to the patentee or the applicant for the patent, as the case may be, and to any other person who appears to him to be concerned, and shall give such patentee or applicant or other person an opportunity of being heard before making the order.