PCT Receiving Office Guidelines
Chapter IV: Article 11(1) Check: Requirements for International Filing Date
Error by the Receiving Office
51. If the receiving Office discovers or, on the basis of the applicant’s reply, realizes that it should not have issued an invitation to correct since the requirements under Article 11(1) were fulfilled when the papers were received, it proceeds as outlined in paragraphs 43 and 44 (Rule 20.3(c)).