Version Operation
There is a version element associated with each Virtual Channel Description, Virtual Channel Map, and Master SI table. A version is changed when any element, attribute, or linked file is modified. Since it expected that the System Information is stable once a network has been established, this allows for the ITF Device to monitor only one file, the Master SI table, to know that a value has changed. It will then be a simpler matter to follow the version chain to find out what parameter has changed. Note that this implies that the Master SI table is multicast pushed to the ITF devices.