IdentifiedObject: This is a root class to provide common identification for all classes needing identification and naming attributes.
ReportingGroup: A reporting group is used for various ad-hoc groupings used for reporting.
Terminal: An AC electrical connection point to a piece of conducting equipment.
TopologicalNode: For a detailed substation model a topological node is a set of connectivity nodes that, in the current network state, are connected together through any type of closed switches, including jumpers.