|Description||string||RelatedTopologyGraph associates a TopologyGraph instance with a ConnectivityCollection. This relationship is different from a topology graph collecting ConnectivityCollections. It describes the embedding of a lower layer topology within a ConnectivityCollection. For example, a layer 3 IP subnet (represented by an instance of IPConnectivitySubnet) collects a set of IPProtocolEndpoints. It might also be associated with a TopologyGraph describing the layer 2 switched Ethernet topology over which the IP subnet runs. This association of Layer 3 to Layer 2 is described as a Dependency relationship, where the Layer 3 connectivity is dependent on the Layer 2 topology.