If a type in this specification lacks information for a specific scenario, it is possible to extend the type. This is done in a specific namespace to indicate that it is outside the scope of this specification. To extend a type, a subtype containing the additional information is created. Instances of this subtype can be used interchangeably with instances of its parent type in the overall Machine Tools node structure. As the subtyped object needs to contain all information the parent type requires, all clients using this specification can handle the information of the supertype in the subtype. Clients that don’t know the subtype might not use its additional information though.