PCT International Search and Preliminary Examination Guidelines
8.01 Mistakes which are due to the fact that something other than that which was obviously intended were included in the contents of the international application or in a later submitted paper (for example, linguistic errors, spelling errors) may be rectified if a request for rectification is submitted within 26 months from the priority date and the necessary criteria are met. The mistake must be “obvious” in the sense that it is obvious to the competent authority:
(i) that something else was intended than what appears in the document concerned; and
(ii) that nothing else could have been intended than the proposed rectification.
8.02 It must be clearly apparent to the competent authority that a mistake was made. No special attributes are ascribed by Rule 91 to the person in the competent authority making the finding whether an alleged mistake is obvious and thus rectifiable. It is thus left to the practice of each authority as to whether, for example, the notional reader should in all cases be an average person with no special skills or, particularly in cases of mistakes in the description, claims and drawings, a “person skilled in the art”. The competent authority makes the determination whether a mistake is rectifiable.
8.03 In the context of Rule 91, the word “authority” may, depending on the circumstances as set out in the Rule, refer to the receiving Office, the International Bureau, the International Searching Authority or the International Preliminary Examining Authority (see paragraph 8.12).
(i) the recognition that there was indeed a mistake; and
(ii) an assessment as to whether the proposed rectification was the only meaning which could have been intended.
In other words, it first must be apparent that a mistake has been made. Then it must be clear that nothing else could have been intended other than the proposed rectification.
8.05 Examples of obvious mistakes that are rectifiable include linguistic errors, spelling errors and grammatical errors, so long as the meaning of the disclosure would not change if the rectification was made. An obvious mistake is not solely limited to such kinds of mistakes, but for the correction to the description, claims, or drawings, the finding by the competent authority as to whether an alleged mistake is obvious must be made only on the basis of the description, claims and drawings,without any reliance on extrinsic documents. The contents of priority documents should not be taken into account for the purposes of considering whether mistakes in the description, claims or drawings are obvious and thus rectifiable. Mistakes in a chemical or mathematical formula would not generally be rectifiable unless the correct formula was common knowledge.
(i) in the request part of the international application or a correction thereof; or
the finding of the competent authority takes into account only the contents of the international application itself and, where applicable, the correction concerned, or in said document, together with any other document submitted with the request, correction or document, as the case may be, any priority document in respect of the international application that is available to the authority in accordance with the Administrative Instructions, and any other document contained in the competent authority’s international application file at the applicable date under paragraph 8.07.
(i) where the alleged mistake is in a part of the international application as filed (including the request – see Article 3(2)): the international filing date;
(ii) where the alleged mistake is in a document other than the international application as filed, including a mistake in a correction or an amendment of the international application: the date on which the document containing the alleged mistake was received.
Where the alleged mistake is in a part of the international application as filed, the two-part rectification test discussed in the paragraph 8.04 must be applied as at the international filing date. Knowledge that came into being after the international filing date may not be used to rectify such a mistake. Where the alleged mistake is in another document, the two-part test must be applied as at the date on which the document was filed. Knowledge that came into being after that date may not be relied upon.