Germany has created free licences some years ago. They are fully comparable to CC0 and CC BY.
- Data licence Germany - Zero - Version 2.0 (dl-de-zero-2.0)
- Data licence Germany – attribution – version 2.0 (dl-de-by-2.0)
I suggest to add these 2 licences because some German municipalities are publishing Open Data sets under dl-de-zero-2.0 and (dl-de-by-2.0
This way we can add these datasets to the DATA namespace on Wikimedia Commons.