diff --git a/developer_manual/digging_deeper/api.rst b/developer_manual/digging_deeper/api.rst
index 4a2fe107224..0df5cb20391 100644
--- a/developer_manual/digging_deeper/api.rst
+++ b/developer_manual/digging_deeper/api.rst
@@ -15,11 +15,13 @@ PHP testing API
 To avoid releasing incomplete public API, it is possible to release a
 testing version of the future API in the NCT namespace, following these rules:
 
-- An API can only live in this testing namespace for one major release,
-- Once tested, the API will be removed entirely or moved to the OCP public namespace,
-- If the API is not removed, the version from the NCT namespace will be marked as deprecated,
-- Deprecated API from the NCT namespace are kept for 2 major releases,
 - Code quality, comments, tests and psalm check are expected to be identical to the OCP namespace.
+- Classes must be tag as `@experimental`, including the current version of Nextcloud.
+- An API can only live in this testing namespace for one major release.
+- During this testing phase, the code and the API can be modified/restructured without limitation.
+- Once tested, the API will be removed entirely or copied to the OCP public namespace.
+- If the API is not removed, the version from the NCT namespace will be marked as deprecated.
+- Deprecated API from the NCT namespace are kept for 2 major releases.
 
 .. note::
   - API within the testing namespace might not have documentation other than in-code comments.