Open .xml files with a spreadsheet software (like Excel).
FSE
Version 2024 will be the only supported version server side by ELSTER as of 2026-04-27.
Version 2024 has significant structure and format changes compared to version 2023 (cf. examples in your repository) and can be used productive since 2025-11-24.
On 2026-02-23 an updated version of the plugin ElsterFSE_KapG_202401 will be released, to introduce a character limit of max. 72 charachters in field /KapG/Nachreichung/NrgFreierEintrag.
Exceeding currently this limit of 72 characters in the field /KapG/Nachreichung/NrgFreierEintrag might cause processing issues on ELSTER side (more information ELSTER-Forum).