Typically, the components of an ObjectType are fixed and can be extended by subtyping. However, since each Object of an ObjectType can be extended with additional components, this standard allows extending the standard ObjectTypes defined in this document with additional components. Thereby, it is possible to express the additional information in the type definition that would already be contained in each Object. Some ObjectTypes already provide entry points for server-specific extensions. However, it is not allowed to restrict the components of the standard ObjectTypes defined in this standard. An example of extending the ObjectTypes is putting the standard Property NodeVersion defined in OPC 10000-3 into the BaseObjectType, stating that each Object of the Server will provide a NodeVersion.