This option remember your preferred file format to save the result.
The format can be one of these three:
A file will be created for every tables (data to export) when saving the result in Hyper-Text Markup Language or Comma-Separated Values format. The name of the table will be appended at the end of the filename (e.g. Warehouses to Customers-Distance.csv).
Saving the result with more than 256 columns is not possible in MS Excel 97-2003 or MS Access 2000 due to column limitation. If ever the limit is exceeded, those two formats will not be available to save the file.