NAPLPS

NAPLPS (North American Presentation Level Protocol Syntax) is a system for expressing graphics in terms of character-based commands which was developed beginning in the 1970s for use in videotex / teletext systems, and was used as late as the 1990s in the Prodigy service and on some bulletin board systems. It can be used with 7-bit ASCII (characters #0-#127 decimal), but "extended" versions also exist which define meanings for 8-bit characters outside the 7-bit range (#128-#255 decimal). It uses a variety of characters with both standard ASCII meanings and specific NAPLPS meanings, as well as multi-character escape sequences, for defining various text and graphical screen layouts in a manner that is platform-independent and capable of efficient transmission (e.g., via telephone modem, or between the frames of TV broadcast signals).

Links

 * Wikipedia article
 * Format description (unofficial)
 * Another copy of format description
 * Television Broadcast Videotex (from Canada)