period. (5) A patent of addition shall remain in force for as long as the patent for the main invention remains in force, including any extension of the term thereof in terms of paragraph (d) of section ninety-seven, but no longer, and no fee shall be payable for the renewal of a patent of addition: Provided that, where the patent for the main invention is revoked, the Registrar or the Tribunal, as the case may be, may order that the patent of addition shall become an independent patent in which case— (a) the fees payable in respect of such independent patent and the times for the payment thereof shall be determined according to the date of the former patent of addition; (b) the normal term of the independent patent shall not extend beyond the date on which the patent for the main invention would have expired if it had not been revoked. (6) The grant of a patent of addition shall be conclusive evidence that the invention is a proper subject for such a patent, and shall not be refused, nor shall any such patent be liable to be revoked or invalidated on the ground only that the invention claimed in the complete specification does not involve any inventive step having regard to the main invention, so, however, that the provisions of this subsection shall not apply to an independent patent referred to in the proviso to subsection (5). (7) A patent for a main invention and its patent of addition shall not be capable of assignment apart from one another. (8) An appeal shall lie from any decision of the Registrar under this section. 27 Renewal of patents (1) Subject to subsection (2), every patent shall lapse if the fees prescribed for its renewal are not paid within the prescribed times. [amended by Act 9 of 2002, with effect from the 20th December, 2002.] (2) The Registrar may, upon application by the patentee and subject to the payment of such additional fees as may be prescribed, extend the time for payment of a fee referred to in subsection (1) for a period not exceeding six months. 28 Restoration of lapsed patents (1) Where a patent has lapsed by reason of the failure to pay any renewal fee within the prescribed time or any extension in terms of subsection (2) of section twenty- seven of that time, the patentee may, within three years from the date on which the patent lapsed, apply in the prescribed manner to the Registrar for the restoration of the patent and any patent of addition: Provided that where the patent was held by two or more persons jointly, the application may, with the leave of the Registrar, be made by one or more of those persons without joining the others. (2) An application in terms of subsection (1) shall contain a statement, to be verified in such manner as may be prescribed, fully setting out the circumstances which led to the failure to pay the renewal fee. (3) After receiving an application in terms of subsection (1) the Registrar— (a) may require from the applicant such further evidence as he considers necessary; (b) shall, if he considers it to be necessary or the applicant so requires, permit the applicant to be heard in connection with his application. (4) If the Registrar is satisfied that prima facie the failure to pay the renewal fee was unintentional and there was no undue delay in making the application he shall direct the patentee to advertise the application in the Journal and any person may, within the prescribed period, give notice to the Registrar of opposition to the application on either or both of the following grounds— (a) that the failure to pay the renewal fee was not unintentional; or (b) that there has been undue delay in the making of the application. (5) If, after publication of a notice in terms of subsection (4)—