Maybe I've missed something because I'm coming late to this, but it
surprises me that people do not seem concerned about keeping track of
licenses (not just credit) for the data we'll host.
At least in the EU, recently compiled or modified databases are protected
by database rights. Maybe the WMF is not affected by such restrictions, and
only needs to respect U.S. law. But many Wikidata editors do live in the
EU, and so do many potential re-users of the data, in other Wikimedia
projects and beyond. I'm concerned that failing to keep track of data
licensing will put them at unnecessary legal risk, and will hinder
Wikimedia's wider mission of providing free educational material.
For instance, once Wikidata content is incorporated into Wikipedia
articles, projects like Wikipedia CD Selection (
) might not be
able to freely release their DVD of selected Wikipedia articles in the EU
unless it respects the licenses under which the data has been released.
(Perhaps this is the case already, but Wikidata will make it much more
visible to data owners.) We will find it very difficult to respect these
licenses if we don't keep track of them from the beginning.
Recording the source of the data is a vital part of this, but it isn't
sufficient. For instance, U.K. government data is often released under the
Open Government License (
requires not just credit but (where possible) a link to the license itself.
What to do with data from the EU that's not freely licensed is a thornier
issue. Just adding it to Wikidata is arguably illegal and against WMF's
I'm aware that many people feel database rights are a bad idea (including
me). But they are part of the law in many countries, including Hungary
(where phase 2 will be launched), so we shouldn't just ignore them.
Going back to the original question, I think the database of interwiki
links in Wikipedia is unlikely to creative enough to be copyrightable. The
CC-BY-SA-3.0-unported license used on Wikipedia is silent about database
rights, so databases that are not copyrighted do not trigger the BY-SA
requirements of the license. So I believe Wikidata's current work on
interwiki links doesn't violate CC-BY-SA.