Windows username in log file name

That would be really nice if Windows username could be stored in the name of the log file.
!U should mean username.

Example: !D-!M-!Y-!T_!@_!U.log --> 10-06-2016-132600_ftp.winscp.net_WinUserName.log

You can use environment variables in the path
https://winscp.net/eng/docs/local_path

!D-!M-!Y-!T_!@_%USERNAME%.log

Thank you prikryl! Perfect solution for me. :)