+----------------------+-----------------+-------------------------+
| Confirmation (RUECK) | Counter (RMZHL) | Finish Execution (IEDD) |
+----------------------+-----------------+-------------------------+
|                30116 |               1 | 08/26/2014              |
|                30116 |               2 | 08/27/2014              |
|                30116 |               3 | 09/27/2013              |
+----------------------+-----------------+-------------------------+

SELECT MAX( rmzhl ), iedd FROM afru
                          INTO (@DATA(lv_rmzhl), @DATA(lv_iedd))
                          WHERE rueck = '0000030116'
      GROUP BY rmzhl, iedd.
      ...
      <some fancy code here>
      ...
ENDSELECT.

SELECT SINGLE iedd
  FROM afru
  INTO @DATA(lv_iedd)
  WHERE rueck = '0000030116'
    AND rmzhl = ( SELECT MAX( rmzhl ) FROM afru WHERE rueck = '0000030116' ).