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Digital television is a new, interesting, and rich platform for developing next generation multimedia services. Navigator is the most important service of digital television. It acts as the main index of all services available in set–top box. In this paper, we describe the definition of a Navigator, its functionality, its information retrieval processes, and its information source based on DVB–SI (Service Information) which is multiplexed in MPEG2 Transport Streams (TS). The process of developing a Navigator in Java language is presented. A software model including navigation model, state model of a remote control, and data structures is introduced. Furthermore, a software reference model for DVB–SI demultiplexing is described. Its implementation was based on a client/server approach using the User Datagram Protocol (UDP). The development issues, performance evaluation, and future research topics are given as conclusions.