Design considerations of NAPLPS, the data syntax for VIDEOTEX and TELETEXT in North America

Two new information services, VIDEOTEX and TELETEXT, are now being introduced in the United States and Canada. Both are aimed at displaying frames of information retrieved from a database on a color TV set augmented by logic and memory. The frames are mixtures of characters and graphics. Both services have a very "friendly" user interface. Distinctions between the two lie in the transmission medium used and the extent of and degree of interaction with the database. TELETEXT uses broadcast TV channels and permits retrieval from a small database. VIDEOTEX uses telephone or other data communication lines and allows extensive interaction with a conceptually unlimited database. This paper focuses on design considerations and features for the recently adopted standard, North American Presentation Level Protocol Syntax (NAPLPS). This new standard specifies the data syntax for the encoding of textual and pictorial information in both VIDEOTEX and TELETEXT services in North America. These services were originally introduced in Europe using alphamosaic formats. Characteristics of the American and Canadian environment that have motivated the new standard to include both alphamosaic and alphageometric formats are examined. The paper concludes with a look at possible additions to NAPLPS.