Recently, much attention is focused on data broadcasting systems via the internet or digital broadcasting because of their potential and convenience. The concept of these systems is generally based on the push-type information delivery technology. The push-type information delivery does not require that users behave in an active manner in order to access information resources because the required and/or updated information is transmitted continuously and automatically. Users select

their favorite channels provided by a service server in advance, and then the system will transmit information for each user at regular intervals. Recently, several push technologies, such as Pointcast 1.01) and Castanet 2.02), have been developed. These systems are not only applied to transmit text data but also hypertext and hypermedia data. In these data broadcasting systems, where data at the server side is often updated, one of the important problems is how to maintain the temporal consistency of the transmitted data because not all the transmitted data is received by the clients since client equipments are not always powered on. In this paper, first, we will describe our new version control mechanism by which the temporal consistency is kept at both the server and its clients3,4,5).