Methods in OPC UA do not have a base class that they all derive from; they just all conform to the Method NodeClass. In AML, it is desirable to have a base SUC UaMethodNodeClass that represents the AML base SUC from which all UA Methods are instantiated. Since there is no Node that represents the Method NodeClass in a UA Namespace (because it is built-in to the UA meta-model), the SUC UaMethodNodeClass is defined in this metamodel library.