Sequence Listings – ST.26

Despite concerns expressed by IP practitioners and patent applicants, WIPO has implemented its the new standard on sequence listings (WIPO standard ST.26). It came into force on July 1, 2022, without a transition period.

The new standard differs considerably in its requirements (including the required information).  The table below briefly compares the most relevant differences between ST.25 and ST.26.

Comparison Sequence identifier Organism name To be included Sequence length Uracil representation AA representation Variables Feature location Mixed mode Title of the invention Applicant(s),Inventor(s) Priority information Format
ST.26 (in force) … as DNA, RNA or AA, together with a mandatory molecule type qualifier to further describe (mol_type) - genus/species (Latin),
- virus name
- synthetic construct
- unidentified MUST:
- D-amino acids
- Linear portions of branched sequences
- Nucleotide analogs Prohibited:
< 4 specific defined AA
< 10 specific defined nucleotides "t" = uracil in RNA and thymine in DNA One letter code Default value assumed for "n" and "X" (no definition) Strictly defined location formats
Feature key + qualifier NO longer possible; translation qualifiers to be used Several languages possible One applicant and optionally ONE inventor Only earliest priority can be included XML
ST.25 (old) …. as DNA, RNA or PRT - genius/species (Latin),
- virus name
- artificial sequence
unknown Not required:
- D-amino acids
- Linear portions of branched sequences
- Nucleotide analogs Possible:
< 4 specific defined AA
< 10 specific defined nucleotides "u" was uracil in nucleotide sequences Three letter code "n" and "X" must have a definition in a feature Formats not clearly defined
Feature key only Nucleotide sequences with AA translation shown below was possible One title only All applicants and all inventors All priority information may be included ASCI.txt

It is a challenge to convert sequence listings previously filed under ST.25 into the newer ST.26. However, it is a great relief that the new WIPO software is much easier to handle and makes it easy to export and import for translational purposes. Thus, I trust that we will not only quickly get used to the new standard but may eventually come to love ST.26  

If you have further questions: Here we are

The complete information on the new standard for generating and filing sequence listings, as well as access to the WIPO software can be found here: