user exit for notification

hello gurus,

              to make damage analysis of equipment's in MCI5 report i made damage and cause code as mandatory in notification.(only then order can be created through notification)

               But my user has a problem that he can know the damage and cause only once after finishing the order.

         so am thinking of to have a user exit before completing the order (TECO).

            So my requirement is to have a user exit which doesn't permit the order to complete technically until and unless damage and cause code is entered in notification.

so can any one please suggest me the right user exit which satisfies my requirement.

thank you.