Update license to a less-arcane OSI-endorsed option?

[sadielbartholomew]

We discussed licensing briefly in our ES-DOC team video call this week, prompted by a support email requesting we add an OSI-endorsed license to this particular codebase, specifically:

I would like to ask if an OSI-endorsed license could be added to this repo (and contributor guidelines, Ideally). It would be immensely useful to be able to extend the existing work with additions, or be able to maintain a fork that we could use to expand on existing controlled vocabularies as well as receive upstream changes.

(they did go on to confirm also that they aren't interested in commercially profiting from use of the codebase).

Notably, whilst it is clear that the current license, 'CECILL-2.1' as registered in a plain text file under the root directory of the repo, is in fact OSI-endorsed, since it is confirmed as such here on an official listing, and we can convey that to the people in question who enquired, (at least) some of us do think it might be beneficial to update the license on this repo (and on other relevant ES-DOC libraries such as pyesdoc) to use a license which is less arcane, since most of the more-common licences e.g. those covered by choosealicense.com are more readily understood by developers, whereas CECILL-2.1 might have to be explicitly pored over. The present license was added ~5 years ago under the consideration of IPSL mostly (hence CECILL which is of French legal origin), apparently, and it appears to be the case also for other ES-DOC libraries where a license has been added.

Considerations

Some considerations with regards to such a possible license update are:

• for any license change it is customary and strictly necessary to contact all contributors to the codebase, though for our core ES-DOC libraries this is only a small number of (mostly if not all) core team members so shouldn't be time-consuming or difficult;

• CeCILL is in fact consistent with the GNU GPL, e.g. as stated by the GNU here:

  The CeCILL is ... explicitly compatible with the GNU GPL.

  and therefore a direct switch to the well-known GNU GPL-3.0 (v3 being the latest, but v2 also being a possibility) could be intuitive and simplest?

• after surveying the repos under the ES-DOC organisation, I see that many other repos initiated several years ago that have CECILL-2.1 but some newer ones that have GNU GPL v3.0 already, such as esdoc-cdf2cim-archive and devops;

• we agreed we should check with relative organisations such as IS-ENES3 before making such a change, if we did want to go ahead with a change.

Parties

For the attention of @davidhassell ,@bnlawrence, @asladeofgreen, @charliepascoe, @AtefBN, @MartinaSt, and anyone else with an investment here initially. I am sending an email to everyone mentioned and including someone relevant from IS-ENES3 in order to broadcast this where it can have everyone's attention since I know many don't monitor GitHub 'mentions', but this Issue (referenced) might be a better place, being open, to register thoughts and in particular approval or otherwise, than in a closed email thread.