An applicant can request authorisation to rectify obvious mistakes in the international application.

If the RO finds defects under Art. 14(1)(a), it invites the applicant to correct them by submitting replacement sheets which will be stamped "SUBSTITUTE SHEET (RULE 26)", and these will retain the original filing date if submitted within the set time limit.[Art. 14; Rule 26; ]

The sole purpose of the title is to inform the public about the technical information disclosed in the application.

It is normally not possible under Art. 34(2)(b) to add completely new drawings to an application, since in most cases a new drawing cannot be unambiguously derivable from the mere text of the description. For the same reasons amendments to drawings should be carefully checked for compliance with Art. 34(2)(b).

For drawings based on the priority document, see GL/PCT‑EPO H‑II, 2.2.2 and subsections.

The examiner should apply the guidelines of section H‑V, 4.1, in the Guidelines for Examination in the EPO mutatis mutandis.

The EPO applies option GL/ISPE A20.21[2] of the Appendix to Chapter 20 of the ISPE Guidelines.