let t d_info = t_record
          [| pack (t_option d_info);
             pack (t_list (t_tuple [| p_int; pack d_info |]));
             pack (t_list (t_tuple [| Locations.Zone.packed_descr;
                                      pack d_info |]));
             pack (t_option d_info);
             pack (t_list (t_tuple [| Locations.Zone.packed_descr;
                                      pack d_info |]));
          |]