If you are using Visio as a source format, you do not have an object-oriented database as the source of the file. In addition to this, even though Visio uses templates and stencils, it does not force a user to use certain shapes for a well-defined object. Therefore, the quality and consistency of the source Visio files determines the success of an import.
Before a Visio import can happen, the mapping of Visio stencils and shapes to ARIS model, object and connection types need to be done. This is only needed for Visio imports (and not for other source file types, which rely on an industry standard), and there can only be one mapping at a time.
You find the "mapping.xml" in Administration > Evaluations > Reports > Visio import.