*... Sum Functions
*...... if Count Field not requested -> eliminate
  if ls_layout-countfname is initial.
    lt_extab-fcode = '&COUNT'.
    append lt_extab.
  else.
    l_count_field = 'X'.
  endif.
[b]*...... if no field allows a sum then eliminate sum function[/b]
  read table lt_fieldcat transporting no fields
             with key no_sum = space
                      tech   = space.
  if sy-subrc ne 0.
    lt_extab-fcode = '&FG_SUM'.
    append lt_extab.
  endif.
[b]*...... if one field allows a sum and is not displayable then
*       sum function must be deactivated
*...... if one field allows a sum and is displayable then
*       sum function must be available[/b] 
         read table lt_fieldcat transporting no fields
             with key no_sum = space
                      no_out = space
                      tech   = space.
  if sy-subrc ne 0.
    lt_extab-fcode = '&FG_SUM'.
    append lt_extab.
  endif.
[b]*...... if no Sum Functionality is requested -> eliminate[/b]
  if gt_grid-s_layout-no_sumchoice eq abap_true or
    ( gt_grid-s_layout-no_totalline = abap_true and
      gt_grid-s_layout-no_subtotals = abap_true ).
    lt_extab-fcode = '&FG_SUM'.
    append lt_extab.
  endif.
  read table lt_extab transporting no fields with key fcode = '&FG_SUM'.
  if sy-subrc eq 0.
    lt_extab-fcode = '&UMC'.
    append lt_extab.
    lt_extab-fcode = '&AVR'.
    append lt_extab.
    lt_extab-fcode = '&MIN'.
    append lt_extab.
    lt_extab-fcode = '&MAX'.
    append lt_extab.
    if l_count_field eq space.
      lt_extab-fcode = '&COUNT'.
      append lt_extab.
    else.
      delete lt_extab where fcode eq '&FG_SUM'.
    endif.
  endif.

[b]*... Subtotal Functions
*...... if no Sum Functions are available -> eliminate[/b] 
           read table lt_extab transporting no fields
                      with key fcode = '&FG_SUM'.
  if sy-subrc eq 0.
    lt_extab-fcode = '&FG_SUBTOT'.
    append lt_extab.
  endif.
  if gt_grid-s_layout-no_subchoice eq abap_true.
    lt_extab-fcode = '&FG_SUBTOT'.
    append lt_extab.
  else.
    call function 'LVC_KKB_SUBTOTALS_CHECK'
         exporting
              it_fieldcat_lvc         = lt_fieldcat[]
              is_layout_lvc           = ls_layout
*           I_LISTTYPE              =
*           I_INCL_INVISIBLE_FIELDS =
         exceptions
              no_subtotals_by_layout  = 1
              no_subchoice_by_layout  = 2
              no_do_sum_by_fieldcat   = 3
              others                  = 4.
    if sy-subrc <> 0.
      lt_extab-fcode = '&FG_SUBTOT'.
      append lt_extab.
    endif.
  endif.
*...... if no Subtotal Functionality is requested -> eliminate
  read table lt_extab transporting no fields
                      with key fcode = '&FG_SUBTOT'.
  if sy-subrc eq 0.
    lt_extab-fcode = '&SUM'.
    append lt_extab.
    lt_extab-fcode = '&AUF'.
    append lt_extab.
  endif.