Element Referencing
It's a modeler, not a drawing tool
No matter you want to add supplementary reference to a model elements, or to establish a referencing relationship among elements, you can easily achieve thorugh the reference feature.
The reference feature allows you to add different kinds of reference to model elements: File, Folder, UML, model element, diagram, shape, etc. Best of all, the references are not just navigable within the editor but also from the documents generated / published.