TODO: Define attribute server API
diff --git a/TODO b/TODO
index 1d4e789..b4682e8 100644
--- a/TODO
+++ b/TODO
@@ -129,3 +129,11 @@
 
   Priority: Low
   Complexity: C2
+
+- Define attribute server API. External applications needs to register,
+  change attributes and to be notified about changes. Example: Proximity,
+  Time and Alert Profiles. "Local Service hierarchy" in the attribute-api
+  needs to be proposed and a RFC shall be sent to the ML.
+
+  Priority: Low
+  Complexity: C2