Declaration Types in rpg 4 program

 Blank                                                            
     Leave the field blank if this specification does not define a
     data structure, a constant, a standalone field, an array, or a
     table.                                                       
                                                                  
 DS                                                               
     Type DS if this specification defines a data structure.      
                                                                  
 C                                                                
     Type C if this specification defines a constant.             
                                                                  
 PI                                                               
     Type PI if this specification defines a procedure interface. 
                                                                  
 PR                                                               
     Type PR if this specification defines a prototype for a call.
 S                                                                
     Type S if this specification defines a standalone field, an  
     array, or a table.