A common way to extend CIM classes is to define derivatives of the CIM class. When a client requests objects of the type for CIM_Process, it is possible to return instances that are actually of a derived type such as Vendor_Process. The WS-Management CIM Binding Specification defines details for handling polymorphism in the resultSet, as specified in [DMTF-DSP0227] section 9.3.
The Web Services Management Protocol Extensions for Windows Vista service MUST ignore the PolymorphismMode element.
The Web Services Management Protocol Extensions for Windows Vista service MUST return instances of both base and derived classes. Each returned instance MUST contain the properties of the base class. Each returned instance MAY omit the properties from the derived classes and MAY set the instance type of derived classes to the base class.