{ .... }
type
 VA_FN = function(const par1, par2{, ...}: Pointer): Boolean;
  cdecl varargs;
{ .... }
//
// varargs without "external" keyword
//
function fn(const par1, par2{, ...}: Pointer): Boolean; cdecl;
var
 last_arg: Pointer absolute par2;
 ptr_args: array[0..MAXLONG shr 2] of Pointer absolute last_arg;
 dw_args: array[0..MAXLONG shr 2] of Cardinal absolute last_arg;
 s_args: array[0..MAXLONG shr 2] of PChar absolute last_arg;
 w_args: array[0..MAXLONG shr 2] of WideString absolute last_arg;
begin
 // ptr_args[1] is first optional argument
 Result := (ptr_args[1] {par3} = Pointer(1)) and
  (dw_args[2] {par4} = 2) and
  (string(ptr_args[3]) = 'CHAR') and
  (w_args[4] = 'WCHAR');
end;
procedure test_fn;
begin
 // VA_FN typecast
 VA_FN(@fn)({par1}nil, {par2}nil, {par3}Pointer(1), {par4}2, {par5}'CHAR',
  {par6}WideString('WCHAR'));
end;