Default Notification interval

[meolic]

We have a service, where notification interval is not specified. No template is used for this service. The definition is as shown below. The question is, what is the default notification interval? In fact, we get re-notifications for this service every 2 hours. But, the server may be somehow changed by previous admin and I do not know, what has been changed after the installation. Where to check for default notification interval? I would expect, that if I use an empty value for notification interval (i.e. leave it out from the definition) then this should be the same as value 0, i.e. re-notifications should not be sent.

define service {
host_name localhost
service_description notify_main_10min
check_command notify_main!600!!!!!!!
max_check_attempts 1
check_interval 1
retry_interval 1
active_checks_enabled 1
passive_checks_enabled 0
check_period 24x7
obsess_over_service 0
check_freshness 0
event_handler_enabled 0
flap_detection_enabled 0
process_perf_data 1
notification_period 24x7
notifications_enabled 0
contacts admin
stalking_options n,
register 1
}

[ssax]

The notification interval would be inherited from the host if not defined on the service.

I just removed it from both the host and the service and removed all the templates from both and mine is showing 30 so they must have 30 hardcoded somewhere.