The Korean Intellectual Property Office (KIPO), along with other intellectual property offices all over the world, adopted the new ST.26 standard for nucleotide and amino acid sequence listings, which went into effect worldwide on Friday, July 1, 2022. The ST.26 (XML) is a new standard for the presentation of nucleotide and amino acid sequence listings in patent applications proposed by the World Intellectual Property Organization (WIPO). 

The previous ST.25 (TXT) standard had some deficiencies, which prompted WIPO to adopt the new standard. For example, because the ST.25 format was not compliant with that of internationally recognized nucleotide sequence databases, data could have been lost when a nucleotide sequence in the ST.25 format was entered into public databases (e.g., NCBI). In addition, since the ST.25 rules were not clear, intellectual property offices worldwide interpreted and enforced the rules differently. Further, sequence types that are common today (e.g., nucleotide analogs, D-amino acids, branched sequences) are not covered by ST.25 rules. Finally, data in the ST.25 format are not structured, making the format difficult to use for automated validation and data exchange.

As a result, at the fifth session of the Committee on WIPO Standards (CWS) held in 2017, Member States of the WIPO agreed to adopt WIPO Standard ST.26 for all national, regional and international-level patent applications which contain sequence listings. In view of WIPO's adoption of ST.26 as the standard for presenting nucleotide and amino acid sequence listings, KIPO has also adopted the ST.26 (XML) system.

KIPO announced that the following patent applications should be filed under the ST.26 format:

• Patent / utility model applications filed on or after July 1, 2022.
• Applications claiming Paris Convention priority that are filed on or after July 1, 2022 (not based on the priority date): as a result, the required formats may be different between the priority application and the subsequent application.
• PCT applications filed on or after July 1, 2022 and their national phase applications (not based on national phase entry date): thus, for KR national phase applications, the ST.26 format is required only for the cases where international filing date is on or after July 1, 2022.
• Divisional applications, converted applications, split-off applications, or applications by legitimate right-holders, whose parent or original application is filed on or after July 1, 2022 (not based on the filing date of the follow-on application): for example, for a divisional application filed after July 1, 2022 whose parent application was filed before July 1, 2022, a sequence listing may be submitted in ST.25 format.

Under the ST.26 system, the sequence listing should only be electronically submitted (i.e., not on paper) and should be submitted in XML format, instead of TXT format. Also, unlike ST.25, the ST.26 system requires the following: (i) D-amino acid, (ii) Linear portions of branched sequences, and (iii) nucleotide analogs, if applicable. For annotation of sequences, the ST.26 system requires not only feature keys (i.e., description of one or more residues of a sequence identified by location) but also qualifiers (i.e., further description of features). Lastly, the ST.26 system does not allow the inclusion of sequences having fewer than 10 specifically defined nucleotides, or fewer than four (4) specifically defined amino acids. The sequence listings may recite the relevant sequence identification numbers (i.e., an "intentionally skipped sequence" or an empty/placeholder sequence) for short sequences, while the details should be described in the specification.

For applications that do not comply with the ST.26 system, KIPO announced that it will not provide any grace period for submitting the sequence listing under the ST.26 format. If a patent application is filed under the non-compliant format (e.g., ST.25 format), the applicant may substitute with the compliant ST.26 format voluntarily or in response to an office action issued by KIPO. However, since the new format is intended to include more details of the sequence compared to the old format, a new matter issue may arise, unless those details are sufficiently supported by the originally-filed specification. Thus, we recommend paying extra attention to the format of the sequence listing and making sure that the right format is filed. KIPO will be establishing a system to ensure that the sequence listings are submitted in the proper format, depending on the application type and the filing date.