diff --git a/message_definitions/v1.0/common.xml b/message_definitions/v1.0/common.xml
index 10da77e4ba..081fbfdf0a 100644
--- a/message_definitions/v1.0/common.xml
+++ b/message_definitions/v1.0/common.xml
@@ -1417,7 +1417,7 @@
         <param index="1" label="Start Engine" minValue="0" maxValue="1" increment="1">0: Stop engine, 1:Start Engine</param>
         <param index="2" label="Cold Start" minValue="0" maxValue="1" increment="1">0: Warm start, 1:Cold start. Controls use of choke where applicable</param>
         <param index="3" label="Height Delay" units="m" minValue="0">Height delay. This is for commanding engine start only after the vehicle has gained the specified height. Used in VTOL vehicles during takeoff to start engine after the aircraft is off the ground. Zero for no delay.</param>
-        <param index="4">Empty</param>
+        <param index="4" label="Options" enum="ENGINE_CONTROL_OPTIONS">A bitmask of options for engine control</param>
         <param index="5">Empty</param>
         <param index="5">Empty</param>
         <param index="6">Empty</param>
@@ -3365,6 +3365,12 @@
         <description>Spektrum DSMX</description>
       </entry>
     </enum>
+    <enum name="ENGINE_CONTROL_OPTIONS">
+      <description>Engine control options</description>
+      <entry value="1" name="ENGINE_CONTROL_OPTIONS_ALLOW_START_WHILE_DISARMED">
+        <description>Allow starting the engine once while disarmed</description>
+      </entry>
+    </enum>
     <enum name="POSITION_TARGET_TYPEMASK" bitmask="true">
       <description>Bitmap to indicate which dimensions should be ignored by the vehicle: a value of 0b0000000000000000 or 0b0000001000000000 indicates that none of the setpoint dimensions should be ignored. If bit 9 is set the floats afx afy afz should be interpreted as force instead of acceleration.</description>
       <entry value="1" name="POSITION_TARGET_TYPEMASK_X_IGNORE">