By default, you cannot change the description of a class after it has been read at startup time. The whole Rogue Wave® Server model is considered as stable as soon as a script file is loaded or instances of dynamic objects are created. To change this behavior and to be able to update the Rogue Wave Server model at runtime, you must call the function IlsDynMvServer::CanUpdateModel just after the dynamic server has been initialized by a call to the function IlsDynMvServer::Initialize. You can extend the definition of a class (by adding attributes and relations, for instance) but you cannot remove any existing class members. The new class definition must be a superset of the old class definition.