The frames in a scene are arranged in a tree structure. Frames can have a parent frame and child frames. Remember, a frame that has no parent frame defines a scene and is called a root frame.
Child frames have positions and orientations relative to their parent frames. If the parent frame moves, the child frames also move.
An application can set the position and orientation of a frame relative to any other frame in the scene, including the root frame if it needs to set an absolute position. You can also remove frames from one parent frame and add them to another at any time by using the IDirect3DRMFrame::AddChild method. To remove a child frame entirely, use the IDirect3DRMFrame::DeleteChild method. To retrieve a frame's child and parent frames, use the IDirect3DRMFrame::GetChildren and IDirect3DRMFrame::GetParent methods.
You can add frames as visuals to other frames, allowing you to use a given hierarchy many times throughout a scene. The new hierarchies are referred to as instances. Be careful to avoid instancing a parent frame into its children, because that will degrade performance. Retained Mode does no run-time checking for cyclic hierarchies. You cannot create a cyclic hierarchy by using the methods of the IDirect3DRMFrame interface; instead, this is possible only when you add a frame as a visual.