Creo NC Sheetmetal > Manufacturing Model > Design Model
  
Design Model
The Design (Reference) Model, represents the finished product and is used as the basis for all NC sequences. Select features, surfaces, grain orientation and edges on the design model as references for each NC sequence. Referencing the geometry of the design model sets up a parametric relationship between the design model and the workpiece. When the design model is changed, all associated NC sequences are updated to reflect the change.
The Design (Reference) Model
Before using a sheet metal part as a manufacturing reference model, make sure that it is unbent into the flat state. Add an Unbend All feature if necessary.