This optional parameter specifies the format for each logging
line. You can use this to control exactly what statistics are logged and
in what order they appear.
If Format is not defined, statistics data
will be logged in the following order (also shown is the special character
that is available for that data in the Format specification). All fields
will be colon separated.
# Log the timestamp, objtype, name and average response time
Format %0:%1:%2:%23