(c) The competent authority shall authorize the rectification under this Rule of a mistake if, and only if, it is obvious to the competent authority that, as at the applicable date under paragraph (f), something else was intended than what appears in the document concerned and that nothing else could have been intended than the proposed rectification.

(d) In the case of a mistake in the description, claims or drawings or in a correction or amendment thereof, the competent authority shall, for the purposes of paragraph (c), only take into account the contents of the description, claims and drawings and, where applicable, the correction or amendment concerned.

(b) Where the rectification of an obvious mistake has been authorized under Rule 91.1, the document concerned shall be rectified in accordance with the Administrative Instructions.

Applicants often attempt to rely upon the priority application to establish a basis for obvious mistake. The priority document (application) cannot be used to support obvious mistake corrections to the description, claims, or drawings or in a correction or amendment thereof. The rectification is obvious only in the sense that the competent authority (i.e., the receiving Office, the International Searching Authority, the International Preliminary Examining Authority, or the International Bureau), as appropriate, would immediately realize that something else was intended other than what appears in the document and that nothing else could have been intended than what is offered as rectification. Examples of obvious mistakes that are rectifiable include linguistic errors, spelling errors and grammatical errors so long as the meaning of the disclosure does not change upon entry of the rectification. Changes to chemical or mathematical formulas would not generally be rectifiable unless they would be common knowledge to anyone. A missing chemical formula or missing line of text would not be considered to be an obvious mistake subject to rectification.

Applicants often attempt to rely upon the priority application to establish a basis for obvious mistake. The priority document (application) cannot be used to support obvious mistake corrections to the description, claims, or drawings or in a correction or amendment thereof. The rectification is obvious only in the sense that the competent authority (i.e., the receiving Office, the International Searching Authority, the International Preliminary Examining Authority, or the International Bureau), as appropriate, would immediately realize that something else was intended other than what appears in the document and that nothing else could have been intended than what is offered as rectification. Examples of obvious mistakes that are rectifiable include linguistic errors, spelling errors and grammatical errors so long as the meaning of the disclosure does not change upon entry of the rectification. Changes to chemical or mathematical formulas would not generally be rectifiable unless they would be common knowledge to anyone. A missing chemical formula or missing line of text would not be considered to be an obvious mistake subject to rectification.

Applicants often attempt to rely upon the priority application to establish a basis for obvious mistake. The priority document (application) cannot be used to support obvious mistake corrections to the description, claims, or drawings or in a correction or amendment thereof. The rectification is obvious only in the sense that the competent authority (i.e., the receiving Office, the International Searching Authority, the International Preliminary Examining Authority, or the International Bureau), as appropriate, would immediately realize that something else was intended other than what appears in the document and that nothing else could have been intended than what is offered as rectification. Examples of obvious mistakes that are rectifiable include linguistic errors, spelling errors and grammatical errors so long as the meaning of the disclosure does not change upon entry of the rectification. Changes to chemical or mathematical formulas would not generally be rectifiable unless they would be common knowledge to anyone. A missing chemical formula or missing line of text would not be considered to be an obvious mistake subject to rectification.

Applicants often attempt to rely upon the priority application to establish a basis for obvious mistake. The priority document (application) cannot be used to support obvious mistake corrections to the description, claims, or drawings or in a correction or amendment thereof. The rectification is obvious only in the sense that the competent authority (i.e., the receiving Office, the International Searching Authority, the International Preliminary Examining Authority, or the International Bureau), as appropriate, would immediately realize that something else was intended other than what appears in the document and that nothing else could have been intended than what is offered as rectification. Examples of obvious mistakes that are rectifiable include linguistic errors, spelling errors and grammatical errors so long as the meaning of the disclosure does not change upon entry of the rectification. Changes to chemical or mathematical formulas would not generally be rectifiable unless they would be common knowledge to anyone. A missing chemical formula or missing line of text would not be considered to be an obvious mistake subject to rectification.

Applicants often attempt to rely upon the priority application to establish a basis for obvious mistake. The priority document (application) cannot be used to support obvious mistake corrections to the description, claims, or drawings or in a correction or amendment thereof. The rectification is obvious only in the sense that the competent authority (i.e., the receiving Office, the International Searching Authority, the International Preliminary Examining Authority, or the International Bureau), as appropriate, would immediately realize that something else was intended other than what appears in the document and that nothing else could have been intended than what is offered as rectification. Examples of obvious mistakes that are rectifiable include linguistic errors, spelling errors and grammatical errors so long as the meaning of the disclosure does not change upon entry of the rectification. Changes to chemical or mathematical formulas would not generally be rectifiable unless they would be common knowledge to anyone. A missing chemical formula or missing line of text would not be considered to be an obvious mistake subject to rectification.

Applicants often attempt to rely upon the priority application to establish a basis for obvious mistake. The priority document (application) cannot be used to support obvious mistake corrections to the description, claims, or drawings or in a correction or amendment thereof. The rectification is obvious only in the sense that the competent authority (i.e., the receiving Office, the International Searching Authority, the International Preliminary Examining Authority, or the International Bureau), as appropriate, would immediately realize that something else was intended other than what appears in the document and that nothing else could have been intended than what is offered as rectification. Examples of obvious mistakes that are rectifiable include linguistic errors, spelling errors and grammatical errors so long as the meaning of the disclosure does not change upon entry of the rectification. Changes to chemical or mathematical formulas would not generally be rectifiable unless they would be common knowledge to anyone. A missing chemical formula or missing line of text would not be considered to be an obvious mistake subject to rectification.

(f) The applicable date for the purposes of paragraphs (c) and (e) shall be:

• (i) in the case of a mistake in a part of the international application as filed—the international filing date;
• (ii) in the case of a mistake 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 was submitted.

(c) Where the rectification of an obvious mistake has been authorized, it shall be effective:

• (i) in the case of a mistake in the international application as filed, from the international filing date;
• (ii) in the case of a mistake in a document other than the international application as filed, including a mistake in a correction or an amendment of the international application, from the date on which that document was submitted.

Obvious mistakes in the international application or other papers submitted by the applicant may generally be rectified under PCT Rule 91, if the rectification is authorized, as required, within the applicable time limit. Any such rectification is free of charge. The omission of entire sheets of the international application cannot be rectified under PCT Rule 91. Correction of such mistakes may only be made in accordance with PCT Rule 20.6. Mistakes in the abstract, in amendments under PCT Article 19 (unless the International Preliminary Examining Authority is competent to authorize the rectification under PCT Rule 91.1(b)(iii)), or in a priority claim or in a notice correcting or adding a priority claim where the rectification would cause a change in the priority, also cannot be rectified under PCT Rule 91.

(h) Where the receiving Office, the International Searching Authority, the International Preliminary Examining Authority or the International Bureau discovers what appears to be a rectifiable obvious mistake in the international application or another document, it may invite the applicant to request rectification under this Rule.

(d) Where the competent authority refuses to authorize a rectification under Rule 91.1, the International Bureau shall, upon request submitted to it by the applicant within two months from the date of the refusal, and subject to the payment of a special fee whose amount shall be fixed in the Administrative Instructions, publish the request for rectification, the reasons for refusal by the authority and any further brief comments that may be submitted by the applicant, if possible together with the international application. A copy of the request, reasons and comments (if any) shall if possible be included in the communication under Article 20 where the international application is not published by virtue of Article 64(3).

Rectifications must be authorized:
…
(D) by the International Bureau if the mistake is in any paper submitted to it other than the international application or amendments or corrections to the application.

(f) The applicable date for the purposes of paragraphs (c) and (e) shall be:
…
(ii) in the case of a mistake 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 was submitted.

(c) Where the rectification of an obvious mistake has been authorized, it shall be effective:
…
(ii) in the case of a mistake in a document other than the international application as filed, including a mistake in a correction or an amendment of the international application, from the date on which that document was submitted.

(g) A mistake shall not be rectifiable under this Rule if:

• (i) the mistake lies in the omission of one or more entire elements of the international application referred to in Article 3(2) or one or more entire sheets of the international application;
• (ii) the mistake is in the abstract;
• (iii) the mistake is in an amendment under Article 19, unless the International Preliminary Examining Authority is competent to authorize the rectification of such mistake under paragraph (b)(iii); or
• (iv) the mistake is in a priority claim or in a notice correcting or adding a priority claim under Rule 26 bis.1(a), where the rectification of the mistake would cause a change in the priority date; provided that this paragraph shall not affect the operation of Rules 20.4, 20.5, 26bis and 38.3.

(e) In the case of a mistake in the request part of the international application or a correction thereof, or in a document referred to in paragraph (b)(iv), the competent authority shall, for the purposes of paragraph (c), only take into account the contents of the international application itself and, where applicable, the correction concerned, or the document referred to in paragraph (b)(iv), 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 authority’s international application file at the applicable date under paragraph (f).

(g) A mistake shall not be rectifiable under this Rule if:
…
(iv) the mistake is in a priority claim or in a notice correcting or adding a priority claim under Rule 26 bis.1(a), where the rectification of the mistake would cause a change in the priority date; provided that this paragraph shall not affect the operation of Rules 20.4, 20.5, 26bis and 38.3.

(d) Where the competent authority refuses to authorize a rectification under Rule 91.1, the International Bureau shall, upon request submitted to it by the applicant within two months from the date of the refusal, and subject to the payment of a special fee whose amount shall be fixed in the Administrative Instructions, publish the request for rectification, the reasons for refusal by the authority and any further brief comments that may be submitted by the applicant, if possible together with the international application. A copy of the request, reasons and comments (if any) shall if possible be included in the communication under Article 20 where the international application is not published by virtue of Article 64(3).

(f) A designated Office may disregard a rectification that was authorized under Rule 91.1 only if it finds that it would not have authorized the rectification under Rule 91.1 if it had been the competent authority, provided that no designated Office shall disregard any rectification that was authorized under Rule 91.1 without giving the applicant the opportunity to make observations, within a time limit which shall be reasonable under the circumstances, on the Office’s intention to disregard the rectification.

Obvious mistakes in the international application or other papers submitted by the applicant may generally be rectified under PCT Rule 91, if the rectification is authorized, as required, within the applicable time limit. Any such rectification is free of charge. The omission of entire sheets of the international application cannot be rectified under PCT Rule 91. Correction of such mistakes may only be made in accordance with PCT Rule 20.6. Mistakes in the abstract, in amendments under PCT Article 19 (unless the International Preliminary Examining Authority is competent to authorize the rectification under PCT Rule 91.1(b)(iii)), or in a priority claim or in a notice correcting or adding a priority claim where the rectification would cause a change in the priority, also cannot be rectified under PCT Rule 91.

Obvious mistakes in the international application or other papers submitted by the applicant may generally be rectified under PCT Rule 91, if the rectification is authorized, as required, within the applicable time limit. Any such rectification is free of charge. The omission of entire sheets of the international application cannot be rectified under PCT Rule 91. Correction of such mistakes may only be made in accordance with PCT Rule 20.6. Mistakes in the abstract, in amendments under PCT Article 19 (unless the International Preliminary Examining Authority is competent to authorize the rectification under PCT Rule 91.1(b)(iii)), or in a priority claim or in a notice correcting or adding a priority claim where the rectification would cause a change in the priority, also cannot be rectified under PCT Rule 91.

Rectifications must be authorized:

• (A) by the Receiving Office if the mistake is in the request;
• (B) by the International Searching Authority if the mistake is in the description, claims, or drawings or in a correction thereof or in any paper submitted to that Authority, unless the International Preliminary Examining Authority is competent;
• (C) by the International Preliminary Examining Authority if the mistake is in the description, claims, or drawings or in a correction thereof, or in an amendment under Article 19 or 34, or in any paper submitted to that Authority, where a demand for Chapter II examination has been filed and has not been withdrawn and the date on which international preliminary examination shall start in accordance with PCT Rule 69.1 has passed;
• (D) by the International Bureau if the mistake is in any paper submitted to it other than the international application or amendments or corrections to the application.