343.4—Procedure on complaints.
        
        (a) Responses.
         The carrier must file an answer to a complaint filed pursuant to  section 13(1) of the Interstate Commerce Act within 20 days after the filing of the complaint in accordance with Rule 206.
    
    
        
        (b) Commission action.
         Commission action, including any hearings or other proceedings, on a complaint will be  limited to the issues raised in the complaint.