From Part 5:
The relations between Nodes and ConformanceUnits are defined at the end of the tables defining Nodes, one row per ConformanceUnit. The ConformanceUnit is reflected with a Category element in the UANodeSet file (see OPC 10000-6).

The Nodes defined in a table are not only the Node defined on top level, for example an ObjectType, but also the Nodes that are referenced, as long as they are not defined in other tables. For example, the ObjectType ServerType defines its InstanceDeclarations in the same table, so the InstanceDeclarations are also bound to the ConformanceUnits defined for the table. The table even indirectly defines additional InstanceDeclarations as components of the top-level InstanceDeclarations, that are not directly visible in the table. The TypeDefinitions and DataTypes used in the InstanceDeclarations, and the ReferenceTypes are defined in their individual tables and not in the table itself, therefore they are not bound to the ConformanceUnits of the table. As another example, the OrderedListType references the GeneralModelChangeEventType, which is defined in another table, and therefore not bound to the ConformanceUnits of the table. In case of ambiguity, the Category element of the UaNodeSet file provides the precise information.