|  |  | 
        
          |  |  | 
        
          | AB | 
            
              | Message acknowledgement |  
              | Indicates that an acknowledgement relating to receipt of message is required. |  | 
        
          | AC | 
            
              | Acknowledge - with detail and change |  
              | Acknowledge complete including changes. |  | 
        
          | AI | 
            
              | Acknowledge only changes |  
              | Acknowledgement of changes only is required. |  | 
        
          | NA | 
            
              | No acknowledgement needed |  
              | Specifies that no acknowledgement is needed in response to this message. |  |