Other than the two usual states i.e. Stopped, Running, there are certain intermediate states as well e.g. SERVICE_START_PENDING,SERVICE_STOP_PENDING,SERVICE_PAUSE_PENDING etc.
In order to consider all such states customer can use the provided option e.g.
Not_Stopped could be used as expected state where it will cover all the possible states other than Stopped.
When you first activate a profile for a specific service it will take the current state as the expected state.
It is up to you to configure this to the preferred state if it differs from this.
Probe uses standard system calls to fetch these service states e.g. EnumServicesStatus