Patents [CAP.400 (8) An appeal shall lie from any decision of the Registrar under this Section. (As amended by C.N. No. 185 of 1964; S.l. No. 175 of 1965 and AcT No. 18 of 1980) 31. (I) Subject to the provisions of this section, where an appli­ cation for a patent is pending or has been granted thereon for an invention (hereinafter referred to as the main invention) and the applicant or patentee applies for a further patent in respect of any improvement in or modification ofthe main invention, the Registrar may, if the applicant so requests, grant a patent for the improvement or modification as a patent of addition. (2) Subject to the provisions of this section, where an invention, being an improvement in or modification of another invention, is the subject of an independent patent and the patentee in respect of that patent is also the patentee in respect of the patent for the main inven­ tion, the Registrar may, if the patentee so requests, by order revoke the patent for the improvement or modification and grant to the patentee a patent of addition in respect thereof, bearing the same date as the date of the patent so revoked. (3) A patent -hall not be granted as a patent of addition unless the date ~f lodging of the complete specification was the same as or later than the date of lodging of the complete specification in respect of the main invention . . (4) A patent of addition shall not be sealed before the sealing of the patent for the main invention. and if the period within which, but for this provi Ion. I-Je sealing of a patent of addition could be made under section.' <y-five expires before the period within which the sealing of the patent for the main invention may be so made. the seal­ ing of the patent of addition may be made at any time within the last­ mentioned period. (5) A patent of addition shall remain in force for as long as the patent for the main invention shall remain in force, including any extension of the term thereof but no longer, and no fees shall be payable for renewal of a patent of addition: Provided that. where the patent for the main invention is revoked, the Registrar or the High Court, as the case may be, may order that the patent of addition shall become an independent patent, and 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. but 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 Patents of addition 33