It's simple. Your model must contain a 3D line with the stationing. It is easy to create for example in iCON Office. A lots of model in Czech republic were doing like simple .trm model, but for last year, we push change creating models to .xml where is .trm and .l3d (3D lines) too, so operators are using functions like "hold slope", "side offsett" or u can see "kilometraz" in MC1.