New Zone Event?

[Enodoc]

Is there an event which fires when you go into a new zone (ie, through a loading screen)? I've found EVENT_ZONE_CHANGED which only seems to fire when you enter or leave POI areas, and EVENT_ZONE_UPDATE which I can't find the firing criteria for at all, but nothing for actually entering a new zone (ie, firing for a change of ZoneId or ZoneIndex). Also, what's the difference between ZoneId and ZoneIndex? More functions seem to use the latter.

Thanks for any assistance!