PCT Receiving Office Guidelines
Chapter IX: Nucleotide and/or Amino Acid Sequence Listing
Incorporation by Reference; Missing and Erroneously Filed Parts
227B. Where the sequence listing is furnished to confirm incorporation by reference (Rule 20.6) the receiving Office may seek assistance from the International Bureau in comparing the sequence listing to be incorporated with the sequence listing from an earlier application.
227C. For any sequence listing incorporated by reference or furnished to complete or correct the international application after filing (Rules 20.5 and 20.5bis), the receiving Office makes the appropriate markings in the file name or metadata of the ST.26 XML file. If the receiving Office receives such a sequence listing on a physical medium, the receiving Office labels the medium with the words "SEQUENCE LISTING" together with other markings equivalent to those required for sheets (Sections 308(b) and 308bis to 310ter).