Field help (EXTERASE) 

Information for the monthly DSN:

The Overwrite box is not available for the monthly DSN. On extraction of a monthly DSN, existing records not declared are indeed systematically overwritten.

Information for the leave/return DSN:

If the Overwrite box is checked, the employee data already extracted and not declared will be overwritten by the new extraction.

Information for the contract end DSN:

If the Overwrite box is not checked, the contract data and contract end payment data
already extracted and not declared will be overwritten by the new extraction. If all the data is already extracted and if the Overwrite box is not checked, no data is extracted.