In the assembly mode, it is possible to add or subtract the material of one set of parts to or from another set of parts that are in the same assembly. When this is done, a new feature called a merge or cutout is added to each of the parts to which the action was performed.

If the merge or cutout was created using the Reference option (rather than copy), the new feature will depend on the parts that it references. This means that when retrieving the part with the merge or cutout feature, Creo Parametric will have to retrieve all the reference parts into session in order to re-create the merge. This means that the reference parts have to always reside somewhere where Creo Parametric can find them.

To create a merge or cutout feature without any external references or dependencies, use the Copy option. This will add a new feature to all the parts, but will break all association with the reference parts.

If you often reuse parts in different assemblies, it is not recommended that you use a Reference Merge or Cutout. You will find that many of your parts will become overloaded with external references, and it will become a nightmare to manage all of your models.