PCT International Search and Preliminary Examination Guidelines
8.11 The following authorities are competent to authorize rectifications in the international application and associated papers:
(ii) if the mistake is in the description, claims or drawings or in a correction thereof: the International Searching Authority, unless the International Preliminary Examining Authority is competent under item (iii);
(iii) if the mistake is in the description, claims, drawings or in a correction thereof, or in an amendment under Article 19 or 34, where a demand for international preliminary examination has been made and has not been withdrawn and the date on which the international preliminary examination is to start in accordance with Rule 69.1 has passed: the International Preliminary Examining Authority;
(iv) in the case of a mistake in a document not referred to in items (i) to (iii) submitted to the receiving Office, the International Searching Authority, the International Preliminary Examining Authority or the International Bureau, other than a mistake in the abstract or in an amendment under Article 19: that Office, Authority or Bureau, as the case may be.
8.12 If an International Authority receives a request for rectification of an obvious mistake in the request (where that International Authority is not also the receiving Office) or where it receives any other paper for which it is not the authority competent to authorize the rectification, it transmits that request together with any proposed replacement sheet to the appropriate authority, as listed above, and informs the applicant accordingly. It may, instead of transmitting the request, inform the applicant that the request should be sent to the authority competent to rectify the mistake. For the language(s) in which a request for rectification must be submitted, see Rule 12.2(b).