If you do not specify the file name,
–In Non-ACS mode all the devices from DCR will be exported to the specified server.
–In ACS mode, only the devices that are not configured in ACS will be exported from DCR to the specified server.
The file format is the same as when you export the devices from DCR. If you perform an export to a CSV for example, the tool will use that last file unless another file is specified.