Clarify LTS lifetime
Signed-off-by: Janos Follath <janos.follath@arm.com>
diff --git a/BRANCHES.md b/BRANCHES.md
index a2ea074..0ce47e8 100644
--- a/BRANCHES.md
+++ b/BRANCHES.md
@@ -23,6 +23,9 @@
compatibility on major version changes (e.g. from 3.x to 4.0). We also maintain
ABI compatibility within LTS branches; see the next section for details.
+New LTS branches are usually created around the time of a new major version.
+After a new LTS branch is created, it remains supported for at least 3 years.
+
## Backwards Compatibility for application code
We maintain API compatibility in released versions of Mbed TLS. If you have