A reference is created when one element of a CAD drawing makes use of another element of a design as part of its definition. When all references exist inside a single CAD drawing, the references are considered internal. When one drawing makes use of design elements of a second drawing, this reference is considered to be external. External references in AutoCAD are modeled in Windchill using required EPMReferenceLinks of type, “Drawing Structure.”

By default, all AutoCAD CAD documents are created as CAD document type, CAD Part. However, if you intend to use an AutoCAD drawing as a standard external reference, then it is possible to categorize it as a CAD Part with a special sub-type, Standard Drawing, upon its creation in AutoCAD in order to help with searching for drawings that are regularly used as XREFs.

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".

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".