The set of Objects and related information that the OPC UA Server makes available to Clients is referred to as its AddressSpace. The model for Objects is defined by the OPC UA Object Model (see 4.2).
Objects and their components are represented in the AddressSpace as a set of Nodes described by Attributes and interconnected by References. Figure 3 illustrates the model of a Node and the remainder of 4.3 discusses the details of the Node Model.
Figure 3 – AddressSpace Node Model