The applicable license terms for this are the ones found at European Public License 1.1 without the Appendix.
This specifically means that the "Compatible Licences" described on the article 5 that are listed on the Appendix section of the original license terms do not apply to this software.
In replacement to the Appendix, the author expressily permits the integration of this software as a component or derivated work at projects under GNU AGPL.