DATA: wa_subty       TYPE subty,
          wa_moabw       TYPE subty,
          wa_stext       TYPE sbttx,
          wa_value_tab   LIKE LINE OF value_tab,
          wa_help_fields LIKE LINE OF help_fields,
          lv_param       TYPE c.

    retfield = 'SUBTY'.

    CLEAR wa_help_fields.
    REFRESH help_fields.
    wa_help_fields-tabname    = 'T591A'.
    wa_help_fields-fieldname  = 'SUBTY'.
    APPEND wa_help_fields TO help_fields.

    wa_help_fields-tabname    = 'T591S'.
    wa_help_fields-fieldname  = 'STEXT'.
    APPEND wa_help_fields TO help_fields.

    GET PARAMETER ID 'ZIT0057' FIELD lv_param.

    IF lv_param EQ abap_true.

      SELECT  subty
      INTO wa_subty
      FROM  t591a
          WHERE  infty = flt_val.

        IF ( wa_subty = '1' OR wa_subty = '2' OR wa_subty = '3' ).
          APPEND wa_subty TO value_tab.
          SELECT stext FROM t591s INTO wa_stext WHERE infty = flt_val AND subty = wa_subty AND sprsl = sy-langu.

            APPEND wa_stext TO value_tab.
          ENDSELECT.
        ENDIF.


      ENDSELECT.
    ENDIF.