PendingOrderCancellationReason

 using cAlgo.API;
 namespace cAlgo.Robots
 {
     // This sample shows how to use PendingOrderCancellationReason
     [Robot(TimeZone = TimeZones.UTC, AccessRights = AccessRights.None)]
     public class PendingOrderCancellationReasonSample : Robot
     {
         protected override void OnStart()
         {
             PendingOrders.Cancelled += PendingOrders_Cancelled;
         }
         private void PendingOrders_Cancelled(PendingOrderCancelledEventArgs obj)
         {
             Print(obj.Reason);
             switch (obj.Reason)
             {
                 case PendingOrderCancellationReason.Cancelled:
                     // Do something if order cancelled
                     break;
                 case PendingOrderCancellationReason.Expired:
                     // Do something if order expired
                     break;
                 case PendingOrderCancellationReason.Rejected:
                     // Do something if order rejected
                     break;
             }
         }
     }
 }

 import clr
 clr.AddReference("cAlgo.API")
 # Import cAlgo API types
 from cAlgo.API import *
 # Import trading wrapper functions
 from robot_wrapper import *
 class Test():
     def on_start(self):
         api.PendingOrders.Cancelled += self.on_pending_orders_cancelled
     def on_pending_orders_cancelled(self, args):
         cancelledOrder = args.PendingOrder
         cancellationReason = args.Reason
         print(f"cancelledOrder: {cancelledOrder.Id} | cancellationReason: {cancellationReason}")