diff --git a/AntennaTracker/mode.h b/AntennaTracker/mode.h
index bfdcad9ac7..0b0752cea6 100644
--- a/AntennaTracker/mode.h
+++ b/AntennaTracker/mode.h
@@ -13,6 +13,7 @@ public:
         GUIDED=4,
         AUTO=10,
         INITIALISING=16
+        // Mode number 30 reserved for "offboard" for external/lua control.
     };
 
     Mode() {}