PVInstance
Anything with a place in a 3D scene: parts, models, cameras, null objects, shaders and clouds.
PVInstance is abstract: you never insert one. It is the shared parent of BasePart, Model, Camera, NullObject, Shader and Cloud, so IsA("PVInstance") is true for each of them. It adds no members of its own; each of those classes keeps its own place in the scene, a CFrame or, for a Model, a pivot.
From Instance 22
Subclasses