New norm ST.26 for sequence listings in patent applications will enter into force on 01/01/2022.
It will be compatible with International Nucleotide Sequence Database Collaboration (INSDC) database provider requirements.
Whereas the current ST.25 norm is in txt (ASCII format) with numeric identifiers, the new ST.26 norm will be in XML format with elements and attributes.
ST.26 norm will apply for applications with a filing date as of 01/01/2022, while ST.25 will remain effective for applications with a filing date prior to 01/01/2022.
An introduction to norm ST.26 can be found here