The OPC UA Meta Model (the OPC UA Address Space Model) is represented by UML classes and UML objects marked with the stereotype <<TypeExtension>>. Those stereotyped UML objects represent DataTypes or ReferenceTypes. The domain model can contain user-defined ReferenceTypes and DataTypes, also marked as <<TypeExtension>>. In addition, the domain model contains ObjectTypes, VariableTypes etc. represented as UML objects (see Figure B.1).
The OPC Foundation specifies not only the OPC UA Meta Model, but also defines some Nodes to organise the AddressSpace and to provide information about the Server as specified in OPC 10000-5.