9. A method implemented by an apparatus for updating a previously supplied electronic document related to a schedule of broadcasting a plurality of television broadcast programs in a program broadcasting system, wherein the previously supplied electronic document is stored in a client of the program broadcasting system and has a hierarchical structure based on a prescribed syntax, the hierarchical structure including an upper fragment and a plurality of lower fragments located below the upper fragment in the hierarchical structure to describe, for each of the television broadcast programs, a program identifier, a title, broadcast information and corresponding program content information, the method comprising: requesting by the client an updated version for said previously supplied electronic document from a provider in the program broadcasting system; in response to the request, receiving from the provider at the client an update document for updating the previously supplied electronic document, the update document having a structure based on the prescribed syntax and including the upper fragment and an invalid element which indicates an invalid fragment as one of the lower fragments of the previously supplied electronic document, wherein said invalid fragment is related to one of the television broadcast programs scheduled for broadcast in the program broadcasting system; and deleting said invalid fragment from the previously supplied electronic document at said client as indicated by the invalid element in the update document supplied from said provider.
9. A method implemented by an apparatus for updating a previously supplied electronic document related to a schedule of broadcasting a plurality of television broadcast programs in a program broadcasting system, wherein the previously supplied electronic document is stored in a client of the program broadcasting system and has a hierarchical structure based on a prescribed syntax, the hierarchical structure including an upper fragment and a plurality of lower fragments located below the upper fragment in the hierarchical structure to describe, for each of the television broadcast programs, a program identifier, a title, broadcast information and corresponding program content information, the method comprising: requesting by the client an updated version for said previously supplied electronic document from a provider in the program broadcasting system; in response to the request, receiving from the provider at the client an update document for updating the previously supplied electronic document, the update document having a structure based on the prescribed syntax and including the upper fragment and an invalid element which indicates an invalid fragment as one of the lower fragments of the previously supplied electronic document, wherein said invalid fragment is related to one of the television broadcast programs scheduled for broadcast in the program broadcasting system; and deleting said invalid fragment from the previously supplied electronic document at said client as indicated by the invalid element in the update document supplied from said provider. 53. The method of claim 9 , wherein the broadcast information specifies a broadcast service, a broadcast time, and a broadcast duration.