(a) Where the receiving Office receives a correction of defects under Rule 26.4 or authorizes a rectification of an obvious mistake under Rule 91, it shall:
(i) indelibly mark, in the upper right-hand corner of each replacement sheet, the international application number and the date on which that sheet was received;
(ii)indelibly mark, in the middle of the bottom margin of each replacement sheet, the words “SUBSTITUTE SHEET (RULE 26)” (where the replacement sheet contains a correction of defects under Rule 26) or “RECTIFIED SHEET (RULE 91)” (where the replacement sheet contains the rectification of an obvious mistake under Rule 91) or their equivalent in the language of publication of the international application;
(iii) indelibly mark on the letter containing the correction or rectification, or accompanying any replacement sheet, the date on which that letter was received;
(iv) keep in its files a copy of the letter containing the correction or rectification or, when the correction or rectification is contained in a replacement sheet, the replaced sheet, a copy of the letter accompanying the replacement sheet, and a copy of the replacement sheet;
(v) subject to item (vi), promptly transmit any letter and any replacement sheet to the International Bureau, and a copy thereof to the International Searching Authority;
(vi) where transmittals under Article 12(1) have not yet been made, transmit any letter and any replacement sheet to the International Bureau together with the record copy and, except where the international application is considered withdrawn and Rule 29.1(iii) applies, a copy of the said letter or replacement sheet to the International Searching Authority together with the search copy. The record copy and the search copy shall contain any replaced sheet.
(b) Where the receiving Office refuses to authorize the rectification of an obvious mistake under Rule 91, it shall proceed as indicated under paragraph (a)(i), (iii) and (iv) and promptly transmit any letter and any proposed replacement sheet to the International Bureau. If the record copy has not yet been sent to the International Bureau, any letter and any proposed replacement sheet shall be transmitted together with the record copy.