(1) Subject to the provisions of Article 139, a European patent may only be revoked under the law of a Contracting State, with effect for its territory, on the following grounds:
(a) if the subject-matter of the European patent is not patentable within the terms of Articles 52 to 57;
(b) if the European patent does not disclose the invention in a manner sufficiently clear and complete for it to be carried out by a person skilled in the art;
(c) 99 if the subject-matter of the European patent extends beyond the content of the application as filed or, if the patent was granted on a divisional application or on a new application filed in accordance with Article 61, beyond the content of the earlier application as filed;
(d) if the protection conferred by the European patent has been extended;
(2) If the grounds for revocation only affect the European patent in part, revocation shall be pronounced in the form of a corresponding limitation of the said patent. If the national law so allows, the limitation may be effected in the form of an amendment to the claims, the description or the drawings.