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.

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

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: