How should we license this repository?

[namurphy]

This repository will probably contain a combination of source code, Jupyter notebooks, and written/graphical content. The main PlasmaPy repository uses the BSD 3-clause license, which is appropriate for source code. However, the BSD license is not appropriate for written/graphical content, and a Creative Commons license would work better.

We should clarify the licensing of this repository (as well as similar other PlasmaPy repositories) as early as we can so that we don't have to change licensing later on (which can get messy). Here is my first attempt at language in LICENSE.md that I am hoping will clarify what license is used for which part of the project:

Source code files and code snippets included in this project are licensed under the BSD 3-clause license. All other content in this project (including content produced by source code and code snippets) is licensed under the Creative Commons Attribution 4.0 International (CC BY 4.0) license.

Is this language sufficient? Is there anything we should add or clarify?

[namurphy]

Here is some sample language from the choosealicense GitHub repository:

The content of this project itself is licensed under the Creative Commons Attribution 3.0 license, and the underlying source code used to format and display that content is licensed under the MIT license.

[namurphy]

Another possibility is using the Creative Commons Attribution-ShareAlike 4.0 International (CC BY-SA 4.0) which requires derivative works (as opposed to integral works, I guess?) to be shared under the same license as the original. This is similar to a copyleft license.

A big advantage of CC BY-SA 4.0 is that it will allow for greater compatibility with Wikipedia. If we use CC BY 4.0, materials from our repository could be uploaded to Wikipedia, but it would limit our ability to adapt materials from Wikipedia. If we use CC BY-SA 4.0, then we will be more free to share materials back and forth with Wikipedia (with attributions). I'm certain there will be times where Wikipedia has a highly appropriate figure for a tokamak or some other plasma phenomena that we would like to use. An alternative would be to specifically say that figures adapted from Wikipedia are under a ShareAlike license, though this could end up being cumbersome.

At the moment, I am in favor of:

• Using CC BY 4.0 for PlasmaPy Tutorials and PlasmaPy Enhancement Proposals, with the permissive BSD 3-clause license for code.
  • This will allow others to use what is developed here more freely since all others would have to do is provide attribution in order to use the content. I think it is less likely that we will want to use content from Wikipedia for these repositories.
• Using CC BY-SA 4.0 for Plasma Education repository, with the permissive BSD 3-clause license for code.
  • This will make it easier to use content from Wikipedia since we will have much more compatible licenses.