Entity
An entity is any dynamic object in the game, except for those listed below. Each entity can have up to two scripts attached - one for the entity class and one for the entity instance.
Entities are separated into the player entity, items, NPCs, props, cameras and markers.
Non-entities
The following dynamic objects are not backed by any entities and cannot be scripted:
Lights
Lights are part of the the level and cannot be scripted or created dynamically. This includes fireplaces and torches on walls, but not 
Torch items. Some lights respond to the Ignite (
) and Douse (
) spells and can be turned on or off by combining certain items with them using Interact (Double Click).
Arrows
Arrows shot by the player use the graph/obj3d/interactive/items/weapons/arrow/arrow.teo 3D object from the item but are non-interactive except for damaging and being stopped by the first entity or scene mesh that they hit.
Zones
Zones trigger script events but cannot be scripted themselves or created dynamically as they are part of the level.
Spells
New spells cannot be created but spells can be cast with the spellcast command. The spell instances are not entities.