Mustangserver 1.2, available since January 8th, 2024, sported minor changes, the only differences being that /combineXML now supports XRechnung 3 as output and
/parse as well as /invoice2XML accordingly support email addresses of tradeparties, not only of their contacts: Already previously one could validate XRechnung 3.0.

This new version has now been set as default on Monday, 29 January 2024.