claims in respect of any such developments or additions, be deemed to have been made on the date on which the complete specification was lodged at the Patent Office. (7) Where a complete specification claims a new substance, the claims shall be construed as not extending to that substance when found in nature. 10 Effective date of claims of complete specification (1) A claim of a complete specification shall have effect from the date provided in this section in relation to that claim and a patent shall not be invalidated by reason only of the publication or use of the invention, so far as claimed in any claim of the complete specification, on or after the effective date of that claim or by the grant of another patent upon a specification claiming the same invention in a claim of the same or a later effective date. (2) Where the complete specification is lodged in pursuance of a single application preceded by a provisional specification or by a specification which is treated by virtue of a direction under subsection (6) of section eight as a provisional specification, and the claim is fairly based on the matter disclosed in that specification, the effective date of that claim shall be the effective date of the application. (3) Where the complete specification is lodged or proceeded with in pursuance of two or more applications accompanied by such specifications as are mentioned in subsection (2), and the claim is fairly based on the matter disclosed in one of those specifications, the effective date of that claim shall be the effective date of the application accompanied by that specification. (4) Where the complete specification is lodged in pursuance of a Convention application, and the claim is fairly based on the matter disclosed in the application for protection in a Convention country or, if the Convention application is founded upon more than one such application for protection, in one of those applications, the effective date of that claim shall be the effective date of the relevant application for protection. (5) Where, under subsections (1) to (4), any claim of a complete specification would, but for this subsection, have two or more effective dates, the effective date of that claim shall be the earlier or earliest of those dates. (6) In any case to which subsection (2), (3), (4) or (5) does not apply, the effective date of a claim shall be the date of lodging of the complete specification in Zimbabwe. 11 Examination of applications and specifications (1) An application for a patent, including any specification and other document accompanying such application or subsequently lodged within such time as may be prescribed at the Patent Office in pursuance of such application, shall be examined by an examiner for the purpose of ascertaining— (a) whether the application, specification and accompanying documents comply with the requirements of this Act, including whether any of the grounds of opposition specified in subsection (1) of section seventeen are applicable; and (b) in the case of a complete specification lodged after a provisional specification or of a Convention application, whether the matter claimed is substantially the same as that disclosed in the provisional specification or in the application lodged in the Convention country, as the case may be. (2) An examination or investigation required by this Act shall not be deemed to warrant the validity of any patent and no liability shall be incurred by the State, the Minister, the Registrar or any examiner or other officer of the Patent Office by reason of or in connection with any such examination or investigation or report or other proceeding consequent thereon. 12 Ante-dating and post-dating of applications and specifications (1) At any time after an application has been lodged under this Act and before acceptance of the complete specification, the Registrar may, at the request of the applicant and upon payment of the prescribed fee, direct that the application shall be