0.
At startup time, the server sends a startup message to the system
object, with one argument, a list of strings giving the arguments passed
on the command line when the server was invoked.
If you use the set_heartbeat_freq() function to enable the
heartbeat, then the server will send a heartbeat message to the
system object periodically.
Methods on the system object can call administrative functions such as
shutdown() which ordinary objects are not permitted to call. In
most databases, the system object will define methods which allow
certain authorized objects to access these functions.