Model parts in the context of an assembly, using references to other components to complete the design. The design intent for new parts (sizes of features, placement of components in the assembly, etc.) comes from other components in the assembly. Build a virtual part in the context of an assembly by employing Top-Down assembly modeling techniques. Create features in the assembly context by referencing geometry in mating parts. Understand InPlace mates and external references. Identify external references in the FeatureManager design tree.