Article 84 of the European Patent Convention (EPC) requires that the claims of a European patent application “shall define the matter for which protection is sought” and “shall be clear and concise and be supported by the description.”[i] To assist practitioners and patent examiners, the European Patent Office (EPO) provides patent examination guidelines interpreting the EPC. Recently, the EPO updated these guidelines, including Guideline F-IV 4.3, which interprets the requirements of EPC Article 84. New Guideline F-IV 4.3 provides strict description (i.e., specification and drawings) amendment requirements by providing that “[a]ny inconsistency between the description and the claims must be avoided if it could throw doubt on the subject-matter for which protection is sought and therefore render the claim unclear or unsupported under Art. 84,” such as where “[p]art of the description and/or drawings is inconsistent with the subject-matter for which protection is sought.”[ii] This may occur where parts of the description are not encompassed by the wording of the claims or are inconsistent therewith, such as may reasonably result from making amendments to the claims that are narrower than the full scope of the original description. In such situations, Guideline F-IV 4.3 specifically instructs that “[t]he applicant must remove any inconsistencies by amending the description either by deleting the inconsistent embodiments or marking them as not falling within the subject-matter for which protection is sought.”[iii]