Typically, instances of an OPC UA Server depend on the configuration of the Server and are based on TypeDefinitions. However, sometimes there are also standardized Instances defined by Companion Specifications.

Mostly, those are static Nodes which are entry points into the AddressSpace like the “Root” and “Objects” folders of the base specification or the “DeviceSet” of the Devices specification.

Sometimes, there are also standardized Variables (like all the capability and diagnostic information defined in OPC 10000-5). Those are not static but bound to a specific server. To work correctly in an aggregating server, it is important to mark those Nodes in the NamespaceMetadata Object of the Namespace as non-static.