8. A method performed by a server device of a content provider for updating a fragment of an electronic document having a prescribed hierarchical structure based on XML, wherein the fragment is a portion in the prescribed hierarchical structure of the electronic document and describes metadata related to a broadcasting program identified by a program identifier, and wherein a fragment identification identifies said fragment in the prescribed hierarchical structure of the electronic document, wherein said fragment is stored in a storage device of a client of a broadcasting system, the method comprising: receiving a request at the server device for an updated version of said fragment from said client device; and supplying said client device with an update document from the content provider, the update document including an invalid element notifying said client device that said fragment is an invalid fragment, wherein the invalid element in the update document identifies said fragment in the prescribed hierarchical structure using the fragment identification of said fragment in the electronic document.
8. A method performed by a server device of a content provider for updating a fragment of an electronic document having a prescribed hierarchical structure based on XML, wherein the fragment is a portion in the prescribed hierarchical structure of the electronic document and describes metadata related to a broadcasting program identified by a program identifier, and wherein a fragment identification identifies said fragment in the prescribed hierarchical structure of the electronic document, wherein said fragment is stored in a storage device of a client of a broadcasting system, the method comprising: receiving a request at the server device for an updated version of said fragment from said client device; and supplying said client device with an update document from the content provider, the update document including an invalid element notifying said client device that said fragment is an invalid fragment, wherein the invalid element in the update document identifies said fragment in the prescribed hierarchical structure using the fragment identification of said fragment in the electronic document. 9. The method of claim 8 , wherein said fragment is previously supplied from the said server device to said client device.