Many thanks! So it is not possible...

There's no such option. The point of the XML Log file is that you can process and reformat it any way you like.
See https://winscp.net/eng/docs/logging_xml#parse

yes, of course!
When I open an FTP connection in WinSCP it immediately creates a log file, which shows that I opened this connection.
I would like to disable such log files, and create a log file only when I really made an FTP transfer.

Sorry, that's bit vague. Can you describe what exactly do you want to achieve?

Hello
Everytime I open an FTP connection, it creates an XML logfile. Is it possible to restrict the log files for FTP transfers only?

Thank you.