Why is Stan documentation CC-BY-ND?

Hi all, I was writing something to encourage my colleagues to stop recommending CC-BY-NC and I thought I would give Stan as an example of CC-BY, but then I found out it’s CC-BY-ND. Is there a reason why? I found an offer to help change it here, but no reply.
To be clear, I am not a CC expert so am open to whatever the reason is (I mean other than gate-keeping).

I’m also not a CC expert and I’m not sure what the original reason was for that choice. Maybe @Bob_Carpenter knows?

For CmdStanR we’ve always listed the code as BSD and doc as CC-BY (GitHub - stan-dev/cmdstanr: CmdStanR: the R interface to CmdStan · GitHub), but you’re right that the main user’s guide, reference manual and functions reference at Stan Documentation are listed as CC-BY-ND. I honestly didn’t even realize that!

I always assumed all the documentation was CC-BY until the other day when I checked.

But maybe nowadays it’s a way to avoid the documentation being used as training data (as though I believe anyone is checking): https://creativecommons.org/using-cc-licensed-works-for-ai-training-2/ ? Though I doubt that was the rationale…

I’m probably to blame, though it was over 15 years ago, so I’m a little fuzzy on the details. We would have changed to “CC-BY” when this came up last time, but that would require getting permission from everyone who has contributed to the docs, so we just left it.

It’s “ND” (no derivative products) rather than “NC” (non-commercial). So the motivation would have been to stop other people from hosting variant forms of our documentation.

What’s funny is that early in the project, people were turning our doc into books on Amazon, which didn’t violate our license because we didn’t have the “NC” clause. I don’t know that anyone ever bought one, but it’s distracting because people would think it’s an official release.