There is some movement in the metadata world.
DCAT-AP will be the new metadata standard for governmental data.
Most German data centres will be implementing it.
There is a European Joinup with lots of info and a GitHub repo for feedback to the German version.
An adaptation as the OEP metadata is supposable.
To come back to the original topic: The DCAT-AP is licensed under ISA Open Metadata Licence v1.1 .