These events are initiated by the plugin system itself to allow certain functionality to simplify plugin development.
EVENT_PLUGIN_INIT (Execute)
This event is triggered by the MantisBT plugin system after all registered and enabled plugins have been initialized (their init() functions have been called). This event should always be the first event triggered for any page load. No parameters are passed to hooked functions, and no return values are expected.
This event is the first point in page execution where all registered plugins are guaranteed to be enabled (assuming dependencies and such are met). At any point before this event, any or all plugins may not yet be loaded.
Suggested uses for the event include:
Checking for plugins that aren't require for normal usage.
Interacting with other plugins outside the context of pages or events.