The VLC line defines basic emulator parameters.

Logfile
Checking the Logfile box enables emulator logging.  By default, the log file name will be <base>.log.  The user has the option to modify the file name and location via the file name field and browse […] button.

Keep
By default, Avanti retains 6 log files.  If a log file is present when Avanti is launched, it is renamed <base>.log;-1.  On a subsequent Avanti launch, it would become <base>.log;-2, and so on.  The user can increase or decrease the number of log files retained using the keep field.