A circuit passing through different vendor equipment (shown as green and blue device symbols) and passing through various protection schemes is modeled by a set of objects that represent physical and logical connections. The LayeredOver relationship is used to define the dependencies between the objects. In GUID-367C4F35-8877-4C39-84D5-9AD1A2589D37.html#GUID-367C4F35-8877-4C39-84D5-9AD1A2589D37___OTM_ELEMENTS_SONET_84906,

when an object is shown vertically above another object, a LayeredOver relationship is implied.