Is CroPL Open Source?
Not if you insist on capitalizing it like that. CroPL is provided as source code (at least), but it’s commercial software, and I place a lot of limitations on your ability to pass it on. That’s “open source” in the old meaning of the words. In the last several years (well, decades), several groups have commandeered the term “Open Source” to mean compliance with various licenses on distribution, usually involving your giving away the code and the rights for the recipients to give it away, too. CroPL is not compatible with any “Open Source” license that I’m aware of.
