External references in models

An external reference is a reference from one model file to an object in another model file.

External references represent objects that exist outside a model file. Typically, external references are resolved automatically without the user knowing.

If you change an external reference and initiate a merge, a difference is registered against the external reference, not against the referenced object.


The following example shows what happens when you change an external reference and initiate a merge.

Model file X has an external reference to an object in model file Y.
  1. User A checks out model file X and changes the external reference to point to an object in model file Z.
  2. User A checks in model file X and initiates a merge with another version of the same model.
  3. The merge registers a difference against the external reference because it now points to a different object.

In this example, if you changed the object in model file Y without changing the external reference from model file X, a difference would not be generated. The state of a referenced object outside a model file is not relevant during a merge.