cas_mon_dbspace_full - Monitor for dbspace_full - writes in 'sysadmin:cas_mon_dbspace_full'
cas_check_dbspace_full - Task for dbspace_full - fires alerts
If all fields empty, the default values from sensor-settings are enabled. You can have a red and yellow alert for megabyte free or percent free. Is both set, only the megabyte value is used. The checkbox ignore says, the dbspace is not checked.
If you empty all fields and press change the default would be enabled.