citation-style-language
Update styles & locales to CC BY-SA 4.0
Perhaps we can look into updating all repository styles and locales to CC BY-SA 4.0, e.g. at the time of the next CSL release. Making a one-time switch would be much easier to manage than allowing 3.0 and 4.0 side-by-side in the repos.
There might be some ways to do this without getting approval from all contributors, which would be hard to get. https://opensource.stackexchange.com/questions/7430/can-i-upgrade-the-version-of-cc-by-sa-from-3-0-to-4-0-in-my-modification suggests 3.0-to-4.0 license upgrades are acceptable for "adaptations" of the original work.
We could thus either make this license switch for a CSL release where we "touch" all styles during the upgrade process to the new CSL version, so we can argue we made an adaptation of each individual style. Alternatively, we could argue we're changing the license of the repository as a whole and treat it as a monolithic object, and just tag/branch the old 1.0.1 styles under their original 3.0 license, and use 4.0 for the "master" branch once we switch it to the next CSL version.
https://creativecommons.org/Version4 and https://www.quora.com/What-are-the-differences-between-Creative-Commons-V3-0-and-V4-0 describe some changes/advantages of the new license. Another small benefit would be that GitHub recognizes CC BY-SA 4.0 so we can properly label the styles and locales repos with this license. See e.g. https://github.com/imthenachoman/How-To-Secure-A-Linux-Server:
I think this is a good idea. At that time, the README or CONTRIBUTING files should be updated to specify that the license may be updated in the future. Something like:
You hereby agree that all contributed Content to the Citation Style Language repositories may be used under the terms of a Creative Commons Attribution ShareAlike 4.0 International license or any later version of a Creative Commons Attribution ShareAlike International License.
From the adaptation perspective, upgrading versions will require at minimum changing the version number and for most styles, some at least minor automatable changes (e.g., removing <category>, changing and="text" to and="long").
At that time, the README or CONTRIBUTING files should be updated to specify that the license may be updated in the future.
We could also have a checklist item in the PR template.
removing
<category>
Where is that discussed?
I see that I misspoke and you only were referring to the field-category.
That ticket was only about removing the CSL terms for the categories, not the categories themselves. See e.g. https://github.com/citation-style-language/locales/commit/0374188ca0784c1d5cde3d1a2655897b9f4c8292#diff-02f55ffcdfd2e4f568976768bb2d97caL81 for their removal from the CSL locale files. I think we should keep labeling styles with the appropriate field categories.
We should also switch all new documentation (like the spec) from CC BY SA 3.0 to 4.0.
Virtually all styles will take an update to replace modified variable names (eg, event to event-title), all locales will take new terms. So we will be in good place to change licenses.