  TYPE
    nat$mdu_data_kind = 0 .. 15,
    nat$mdu_header = packed record
      reserved: boolean,
      kind: nat$mdu_data_kind,
      compressed: boolean,
      field: boolean,
      command: boolean,
      length: 0 .. 255,
    recend;

  CONST
    nac$mdu_binary_string = 0,
    nac$mdu_binary_octet = 1,
    nac$mdu_character_string = 2,
    nac$mdu_unsigned_integer = 3,
    nac$mdu_signed_integer = 4,
    nac$mdu_bcd = 7;

