About Reference Models
The Creo design model, also known as the reference model, represents the finished product and is used as the basis for all manufacturing operations. Features, surfaces, and edges are selected on the design model as references for each tool path. When the design model is changed, all associated manufacturing operations are updated to reflect the change.
Creo NC allows you to assemble the reference model using an existing model. Alternatively, you can assemble the reference model with features inherited or merged from an existing model.