It is a patch on top of an open source license, BSD-2-Clause.
Legal terms aren't exactly like computer code, but the analogy works here. Unmodified BSD-2-Clause meets OSI's "test suite", the Open Source Definition, and FSF's test suite, "What is free software?". Patched, L0-NC fails both test suites. Passing isn't about provenance of the "raw material". It's about what the terms do.
The reason I did that, even though I could easily write a more modern and approachable permissive license than BSD-2-Clause, which is almost as old as I am, was to make automatic reversion back to open source terms very clear. The "patch" touches the header notice, and adds a third condition. The automatic waiver removes the new, third condition. That means BSD-2-Clause and some extra stuff in notice are left.
Legal terms aren't exactly like computer code, but the analogy works here. Unmodified BSD-2-Clause meets OSI's "test suite", the Open Source Definition, and FSF's test suite, "What is free software?". Patched, L0-NC fails both test suites. Passing isn't about provenance of the "raw material". It's about what the terms do.
The reason I did that, even though I could easily write a more modern and approachable permissive license than BSD-2-Clause, which is almost as old as I am, was to make automatic reversion back to open source terms very clear. The "patch" touches the header notice, and adds a third condition. The automatic waiver removes the new, third condition. That means BSD-2-Clause and some extra stuff in notice are left.