--- a/src/ai/api/ai_vehicle.hpp	Tue Mar 27 11:55:16 2007 +0000
+++ b/src/ai/api/ai_vehicle.hpp	Tue Mar 27 11:56:05 2007 +0000
@@ -56,6 +56,9 @@
 	 * @return the VehicleID of the new vehicle, or an invalid VehicleID when
 	 *   it failed. Check the return value using IsValidVehicle. In test-mode
 	 *   0 is returned if it was successful; any other value indicates failure.
+	 * @note in test-mode it means you can't assign orders yet to this vehicle,
+	 *   as the vehicle isn't really built yet. Build it for real first before
+	 *   assigning orders.
 	 */
 	VehicleID BuildVehicle(TileIndex depot, EngineID engine_id);