Hello Ludwig. Try Kreutzer (2011) who analyses the CC0 dedication. His report is useful for servers located in Germany because he quotes German law. Generally the CC0 dedication is recommended over the PDDL dedication for software for reasons I don’t have at hand.
By the way, your opening premise is not quite correct. Copyright protects originality not effort, albeit at a rather low threshold. For instance, the German Copyright Act (UrhG §2(2)) says (emphasis added) “Only the author’s own intellectual creations constitute works within the meaning of this Act.” Other jurisdictions use similar but not identical criteria. The European database right protects effort irrespective of creativity, but that effort must be substantial. Whether either right applies to the metadata associated with an energy dataset depends on the details. HTH, Robbie.
On reflection, it seems to me that a BibTeX entry would not meet the threshold for copyright. Indeed, any number of people should, when presented with the same document, produce, more or less, the same record. But a collection of BibTeX entries which required substantial effort to assemble would attract a European database right. Note that a database right can be waived with a simple statement to that effect.
Another little known Creative Commons instrument is the Creative Commons Public Domain Mark (CC PDM), used to mark works that are already in the public domain. This instrument is to allow such works to be more easily discovered and recognized as such. It should not be used for waiving copyright: the CC0 is provided for that purpose.
The Open Data Commons PDDL dedication is worded in database terms. It might therefore be more appropriate for databases. As noted earlier, the CC0 is strongly preferred for software.
Kreutzer, Till (2011). Validity of the Creative Commons Zero 1.0 universal public domain dedication and its usability for bibliographic metadata from the perspective of German copyright law. Berlin, Germany: Büro für Informationsrechtliche Expertise.