When all references exist inside a single CAD model, the references are considered internal. When one model makes use of geometry in a different file, this reference is considered to be external.

When an external reference is created and managed by Windchill, it is represented by a “reference” link in Windchill.

Windchill is capable of locating all drawings referenced by a drawing model and automatically relating them to the part of the model. In some cases, you may want to distinguish manufacturing drawings versus conceptual drawings by using a link in the database, rather than using the calculated relationship. The preference Create Content Links for Drawings controls whether the auto associate action creates a link in the database. The default is "No".

The Create Content Links for Drawings preference is only available in the Site and Organization contexts.