(b) plant varieties, which are subject to the provisions of Law No. 9/94 on the Protection of Plant Varieties. 25. Methods of surgical or therapeutic treatment for the human or animal body and diagnostic methods applied to the human or animal body shall not be considered industrially applicable inventions for the purposes of Article 22 above. This provision shall not apply to products, in particular substances or compositions, for the implementation of one of these methods. 26. An invention shall be considered to be new if it does not form part of industrial prior art. Prior art shall consist of everything made available to the public by means of written or oral description, use or any other way before the date on which the patent application is filed in Morocco or a patent application is filed abroad, for which priority has been validly claimed. By way of derogation to the provisions of this Article, disclosure of the invention shall not be taken into consideration in the following two cases: (1) if it has occurred in the six months prior to the date of filing of the patent application; (2) if it stems from the publication, after the date of filing, of an application for an earlier patent and if, in either case, it leads directly or indirectly (a) to a manifest abuse practised on the applicant or his legal predecessor; (b) to the fact that the invention has been presented for the first time by the applicant or his legal predecessor at official or officially recognized international exhibitions, organized in the territory of one of the countries of the International Union for the Protection of Industrial Property. However, in the latter case, the fact that the invention has been exhibited must be declared when the application is filed. 27. An invention shall be considered to involve an inventive step if, for a person skilled in the art, it is not obvious from the state of the art. 28. An invention shall be considered industrially applicable if it can be made or used in any kind of industry, including agriculture. 29. Throughout the term of the patent, the patent owner or his successors in title may make improvements or additions to the invention, which shall be evidenced by certificates of addition granted subject to the same formalities and conditions as the main patent and producing the same effects as that patent. The provisions of this Law relating to invention patents shall apply to certificates of addition except for the provisions relating to the term of the patent and to the payment of the prescribed fees for the renewal of said patent, which are provided for in Articles 17(a) and 82 of this Law respectively. The term of protection for the certificate of addition shall end at the same time as that of the main patent. Certificates of addition granted at the request of one of the successors in title shall benefit all of the others.