The objects of the CallbackOptions class determine page behaviour in Callback mode. The collection of the CallbackOption class children contains the list of active elements and controls to be sent to a user in the current request. The PersistControls and GroupControls properties allow showing constantly updatable and group controls, respectively. If any active element is not to call a request in the Callback mode, add its identifier in the NonCallbackControls property. The IsAcceptableControl method allows defining if a control will be sent to a client in the current request. You can influence the operating results of this method in the run-time by assigning your handler to the ControlAccepted event. If, for some reason, you need to change the behaviour of all the objects of this class, you may use its successor with the overrided OnControlAccepted method in your projects. The objects of the CallbackOptions class have no visual effect on a page and they can be located in any place of any template. You can have only one object for the whole project located, for instance, on the main page. It is, however, not convenient to work with. It is more logical to locate the class objects on the templates that have active elements and to list only active elements of this template in the collection of the CallbackOption class, as shown in the demo project.