The export options applicable for Excel export files are as follows:
If you select this check box, the exported Excel file will include metadata about each column from the source database table (name, data type, size).
Include column headers
Select this check box if the exported Excel table is to include the database column names.
Substitution for NULL-values
Select from the list or type the string that should appear in the exported Excel file when there is a NULL value in the data being exported. You can also type in a value that is not contained in the drop-down list.