A method includes maintaining a repository of location identifiers and billing identifiers, wherein each of a plurality of network devices is associated with a location identifier in the repository, and each location identifier is further associated with at least one billing identifier. The CS station also produces symbolic labels indicative of the content of the supplemental programs, and broadcasts the supplemental programs and symbolic labels together. The valve closure member comprises a body and a second frustoconical contact surface that is adapted to seal against the first frustoconical contact surface.