OptionalenabledOptionalpositionOptionalrotationOptionalscaleOptionalcomponentsOptionalchildrenOptionalassemblyWhen set, this object is an assembly instance: its components/children are
not authored inline but materialized from the referenced assembly plus the
link's override delta. components/children are omitted on
such a node. See AssemblyLink and TODO/assembly-system.md.
Quaternion [x, y, z, w]; omit for identity.