1. A method implemented by a client in a broadcasting system for managing metadata for multimedia program content scheduled for broadcast in the broadcasting system, the method comprising: receiving in the client from a provider in the broadcasting system an electronic document containing metadata related to the scheduled multimedia program content, wherein the electronic document has a hierarchical structure based on a prescribed syntax and the hierarchical structure includes an upper fragment located above a lower fragment which is identified by a fragment identification; requesting an update for the previously received lower fragment in the client; and in response to the request, receiving in the client an update document having a structure based on the prescribed syntax, the update document including the upper fragment and an invalid element, wherein the invalid element specifies that information in the previously received lower fragment is invalid.
2. The method of claim 1 comprising deleting the previously received lower fragment in response to receiving the invalid element.