Publishing an event from the Windows SDK - clarification needed

The SDK documentation shows:
ParticleCloud.SharedCloud.PublishEventAsync("event_from_app", "event_payload", true, 60);

by way of example. And that’s it. I can see “event_from_app” must be the event name, and “event_payload” is obvious too. But what is the ‘true’ for? Is this the public/private setting? If I want this event private should this be true or false? Even looking through the Cloud API docs (not the Win SDK docs), it doesn’t actually state whether ‘true’ means ‘private’ or ‘public’, wrt publishing events.

Can anyone enlighten me?