31. 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 attribute specifying that the previously received lower fragment is invalid.
31. 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 attribute specifying that the previously received lower fragment is invalid. 32. The method of claim 31 , wherein the update document includes information which is invalid in the previously received lower fragment.