An applicant can request authorisation to rectify obvious mistakes in the international application (see GL/PCT‑EPO H‑IV, 2). The examiner (if the request relates to the description, claims or drawings) will have to assess whether such a request can be authorised according to the criteria set out in Rule 91 – see GL/ISPE 8.07-8.08. If RO has erroneously authorised such rectification, this may affect the search (see GL/PCT‑EPO H‑IV, 2.1).
If the changes requested by the applicant before the receipt of the ISR are not rectifications, but rather amendments, the examiner must refuse them, because there is no right to amend the application until after the international search report has been established. This applies even if the applicant refers to them as rectifications and even if they would be allowable amendments not adding subject-matter to the application as originally filed. For example, reformulation of claims, deletion of technical terms, deletion or limitation of claims and the taking of subject-matter from the description into the claims must all be refused at this stage regardless of whether or not they might be allowable, since they are not rectifications, but rather substantive amendments.