Sometimes you may want parts or subassemblies to be included on a drawing, but only for reference purposes. Reference parts typically provide a frame of reference for the components in the drawing view to a higher level assembly or to a completed product.
For example, when creating a drawing of the head subassembly (A) for a grinder, you may want to display the case and switch (B) as reference parts to illustrate the relationship between the head subassembly and the completed product.
You can specify that a part or subassembly is a reference part when you are placing a part view of an assembly or you can edit the drawing view properties for the part view later. The Display As Reference option on the Display tab of the Drawing View Properties dialog box allows you to specify that a part or subassembly is a reference part.
In an assembly, you can also use the Occurrence Properties command to specify that an assembly occurrence is a reference part. You can then set the Derive "Display As Reference" From Assembly option on the Drawing View Properties dialog box to display the component as a reference part in the drawing.
When creating a parts list of an assembly, you can use the Exclude Reference Parts option on the List Control tab on the Parts List Properties dialog box to control whether reference parts are included in the parts list.