Clarifications on license

Signed-off-by: Robert Schmidt <robert.schmidt@openairinterface.org>

NOTICE

 <!-- SPDX-License-Identifier: CC-BY-4.0 -->
 
-The source code is distributed under [**Collaborative Standards Software
-License (CSSL) v1.0**](LICENSE).  Some files, such as for orchestration,
-are distributed under [MIT license](preferred)(MIT.txt). Documentation is
-distributed under [Creative Commons Attribution 4.0 International
-license](LICENSES/preferred/CC-BY-4.0.txt).
+The source code is distributed under Collaborative Standards Software License
+(CSSL) v1.0. Some files, such as for orchestration, are distributed under MIT
+license. Documentation is distributed under Creative Commons Attribution 4.0
+International license. All the files without an explicit copyright header have
+an implicit "Copyright of OpenAirInterface Authors".
 
 For more details of the license, refer to the `LICENSES` directory for a list
 of preferred and exceptionally-applied licenses.

README.md

@@ -40,7 +40,18 @@ Some files, such as for orchestration, are distributed under
 [MIT license](preferred)(MIT.txt). Documentation is distributed under
 [Creative Commons Attribution 4.0 International license](LICENSES/preferred/CC-BY-4.0.txt).
 
-Please see [NOTICE](NOTICE.md) for other licenses which are used in the software.
+All the files without an explicit copyright header have an implicit "Copyright
+of OpenAirInterface Authors".
+
+Please see [NOTICE](NOTICE) for other licenses which are used in the software.
+
+In the past OAI source code has been re-licensed sometimes, here is the
+history:
+
+1. CSSL v1.0 starting tag 2026.w14
+2. OAI Public License v1.1 starting tag v1.0 till af4b0d53
+3. OAI Public License v1.0: starting tag v.04 till v1.0
+4. GPL 3: starting tag v.0 till v.04 (only initial implementation of 4G)
 
 # Where to Start #