You can create a new part directly from an existing part. The new part, called a derived part, has the original part as its first feature. By default, the derived part is linked to the original part by means of an external reference. This means that any changes you make to the original part are reflected in the derived part.
When you create a derived part that is linked to the base part, the Description property of the derived part’s cut list uses the same evaluated value as the base part. The derived part’s units and dimensions are disregarded.
When a part has an external reference, its name in the FeatureManager design tree is followed by an arrow ->. To see the name, location, and status of the externally referenced document, right-click the derived part, and select List External Refs.
When you create a derived part by inserting or mirroring a part, you can break the link to the original part so that you can edit the new part and the original part independently. Once broken, references to the original part cannot be restored.
When you derive a component part from an assembly, you can also break the link to the original part by controlling the creation of external references.
There are three types of derived parts: Insert parts, Mirror parts, and Derived component parts.