1. Substitute sheets (Rule 26)

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

In cases where the EPO is not the RO, substitute sheets may already have been allowed by the RO concerned and the file will then contain these substitute sheets in addition to the originally filed documents.

Where the EPO is (S)ISA or IPEA, the examiner must check whether the substitute sheets contain amendments/corrections that go beyond the strict limits of Rule 26 PCT and breach the prohibition on adding subject-matter, and inform the applicant in case substitute sheets under Rule 26 PCT go beyond the disclosure on the filing date.