[Tyhm]

A good clarification for the documentation too.
onCreated - serverside - [this is an example, please don't expect me to be right] called when the NPC is created by the NPCServer, typically when the level is first uploaded or when the NPCServer is restarted. In the case of Non Database NPCs (See Database NPCs, [and that would be a link]), this is also called when the level is updated.
- clientside - called when the NPC is first encountered by the player and thus 'created' locally. Also called when the level is updated. [maybe, depends on if people still use "update level" to restart the NPCs fresh, and if it works clientside, and if it works serverside, all three questions at once.]
onPlayerEnters - serverside - called whenever any player enters the level by any means - walking, warping, connecting, reconnecting, anything. Also checked when the NPCServer restarts or the level is updated, but only if there is a player still in the level (to the NPC, the player just "entered" - "enter" and "poof into existance" are synonimous)
onPlayerEnters - clientside - called whenever the player enters the level. For checking if another player entered their level, you'd need [link to functioncall here].
onHit - serverside - called whenever any damage is dealt to this NPC by any source...

I'm sure I'm beating a dead horse by this point, just speaking to hear myself talk - ye who write the documentation, you get what I'm sayin' right?