Child

From Second Life Wiki

Child refers to an object or agent connected to or associated with another asset. While it is often technically part of the asset, it is not in itself the asset. Prims sub-linked to other prims are an example of a child. An avatar standing in a sim next to the one you are in would be a "child agent" of the sim you are standing in. Similarly, an asset attached to your avatar would also be a child.