Dear Mathieu,

On Wed, Nov 29, 2017 at 10:45 PM, Mathieu Stumpf Guntz <> wrote:

I forward here the message I initially posted on the Meta Tremendous Wiktionary User Group talk page, because I'm interested to have a wider feedback of the community on this point. Whether you think that my view is completely misguided or that I might have a few relevant points, I'm extremely interested to know it, so please be bold.

As having contributed to many open database and as user of many open database, the CCZero is my default choice for making data open. Adoption of this license is, IMHO, the prime reason Wikidata is growing so fast, and integrated so fast in many use cases. License incompatibilities have been a major concern in open source development and academic research. Yes, there too, there is a continuous almost-religious and unsolved discussion about copylefting, but the plain experience there is that the closer to the idea of public domain, the easier it is to use. The advantages of CCZero have been widely discussed in the life sciences, and while not everyone choice, the benefits outweigh the disadvantages for many. I also note that public domain (which CCZero formalizes across jurisdictions) is still the "ideal" license when uploading images to Wikimedia, suggesting more of Wikimedia actually finds the CCZero idea very welcome.

Also stress that in no way I recognize myself in your comments about Denny and Google. And your comment that "freedom of one is murder and slavery of others" needs some refinement, IMHO; my definition of "freedom" is quite different and I experience your definition as abusive and offensive.

The CCZero license of Wikidata is essential to my contributions and use of Wikimedia products. The chemistry knowledge in Wikidata is 100x more useful (to me) than that in Wikipedia etc. That is in part because of the machine readability, but also to a large part by the choice of CCZero.

I hope this helps,

with kind regards,


E.L. Willighagen
Department of Bioinformatics - BiGCaT
Maastricht University (
ORCID: 0000-0001-7542-0286