Call function 'gui_download'

Question

Hallo Friends,
I am using the above fuction in my program. I want the header of my internal table to be writen als header in the text file. So, I created another Itab (Itab-col_1) and appended all the headers in this, which I later use as below.
Problem:
1.
I am not satisfied with the downloaded output in file.txt  I want the header to be excactly over the column content. Please see my output:
MANDT     LIFNR     LAND1     NAME1     NAME2     NAME3
010§§§§§§0000010000§§§§§§§§§§§§§§§§§§DE§§§§§§Test
010§§§§§§0000100000§§§§§§§§§§§§§§§§§§US§§§§§§TEST
§ § means Space
It is Obvious LAND1 should be over DE / US, NAME1 should be over Test / TEST etc etc     
2.
I would like filed seperator to be ( ; ) not space. The flag 'X' gives space.
CALL FUNCTION 'GUI_DOWNLOAD'
    EXPORTING
      filename                  = str
      filetype                    = 'ASC'
      write_field_separator = 'X'
      dat_mode                = 'X'
    TABLES
      data_tab                   = itab_kreditor
      fieldnames                = itab_datei_col_header
    EXCEPTIONS
      file_write_error           = 1
      file_not_found            = 19
      OTHERS                   = 22.
So, how can I solve these two problems.
Blacky.

Answer 1

CALL FUNCTION 'GUI_DOWNLOAD'
  EXPORTING
  BIN_FILESIZE                    = BIN_FILESIZE
    filename                        = filename
  FILETYPE                        = 'ASC'
  APPEND                          = ' '
<b> WRITE_FIELD_SEPARATOR           = ';'</b>
  HEADER                          = '00'
  TRUNC_TRAILING_BLANKS           = ' '
  WRITE_LF                        = 'X'
  COL_SELECT                      = ' '
  COL_SELECT_MASK                 = ' '
  DAT_MODE                        = ' '
  CONFIRM_OVERWRITE               = ' '
  NO_AUTH_CHECK                   = ' '
  CODEPAGE                        = ' '
  IGNORE_CERR                     = ABAP_TRUE
  REPLACEMENT                     = '#'
  WRITE_BOM                       = ' '
  TRUNC_TRAILING_BLANKS_EOL       = 'X'
  WK1_N_FORMAT                    = ' '
  WK1_N_SIZE                      = ' '
  WK1_T_FORMAT                    = ' '
  WK1_T_SIZE                      = ' '
IMPORTING
  FILELENGTH                      = FILELENGTH
  TABLES
    data_tab                        = data_tab
  FIELDNAMES                      = FIELDNAMES
EXCEPTIONS
  FILE_WRITE_ERROR                = 1
  NO_BATCH                        = 2
  GUI_REFUSE_FILETRANSFER         = 3
  INVALID_TYPE                    = 4
  NO_AUTHORITY                    = 5
  UNKNOWN_ERROR                   = 6
  HEADER_NOT_ALLOWED              = 7
  SEPARATOR_NOT_ALLOWED           = 8
  FILESIZE_NOT_ALLOWED            = 9
  HEADER_TOO_LONG                 = 10
  DP_ERROR_CREATE                 = 11
  DP_ERROR_SEND                   = 12
  DP_ERROR_WRITE                  = 13
  UNKNOWN_DP_ERROR                = 14
  ACCESS_DENIED                   = 15
  DP_OUT_OF_MEMORY                = 16
  DISK_FULL                       = 17
  DP_TIMEOUT                      = 18
  FILE_NOT_FOUND                  = 19
  DATAPROVIDER_EXCEPTION          = 20
  CONTROL_FLUSH_ERROR             = 21
  OTHERS                          = 22
IF sy-subrc <> 0.
MESSAGE ID SY-MSGID TYPE SY-MSGTY NUMBER SY-MSGNO
        WITH SY-MSGV1 SY-MSGV2 SY-MSGV3 SY-MSGV4.
ENDIF.
Regards
Vasu