MPEP App. AI, Section 413 – Incorporations by Reference under Rule 20.6, Corrections of Defects under Rule 26.4 and Rectifications of Obvious Mistakes under Rule 91

(a) Where the International Bureau receives from the receiving Office a letter containing a correction of any defects under Rule 26.4, or a replacement sheet and the letter accompanying it, the International Bureau shall transfer the correction to the record copy, together with the indication of the date on which the receiving Office received the letter, or shall insert the replacement sheet in the record copy. Any letter and any replaced sheet shall be kept in the file of the international application.
(b) Paragraph (a) shall apply mutatis mutandis to rectifications of obvious mistakes under Rule 91 authorized by the receiving Office, by the International Searching Authority or, where a demand has been made, by the International Preliminary Examining Authority and to corrections submitted by the applicant to the receiving Office or the International Searching Authority aimed at complying with the prescription of Rule 9.1 concerning certain expressions, drawings, statements or other matter.
(b-bis) Where the International Bureau receives from the receiving Office, under Sections 309(c)(iv), 310(b)(iv), or 310bis(b)(v), corrected sheets of the request or later submitted sheets, the International Bureau shall transfer any correction to the record copy and insert any later submitted sheets in the record copy.
(c) Where the International Bureau is notified by the International Searching Authority under Rule 43.6bis (b) that the rectification of an obvious mistake authorized under Rule 91 has not been taken into account for the purposes of the international search, the International Bureau shall notify the applicant, the designated Offices and, where a demand has been made, the International Preliminary Examining Authority accordingly.
(d) Where the International Bureau is notified by the International Preliminary Examining Authority under Rule 70.2 (e) that the rectification of an obvious mistake authorized under Rule 91 has not been taken into account for the purposes of the international preliminary examination, the International Bureau shall notify the applicant and the elected Offices accordingly.