Teletext and to pad out the fixed packet. The vertical caption position is determined by the packet address. In the case of the Ceefax and ORACLE systems and their successors in the UK, the teletext signal is transmitted as part of the ordinary analog TV signal but concealed from view in the Vertical Blanking Interval (VBI) television lines which do not carry picture information. The teletext signal is digitally coded as 45-byte packets, so the resulting rate is 7,175 bits per second per used lines (41 7-bit 'bytes' per line, on each of 25 frames per second). A teletext page comprises
World System Teletext World System Teletext World System Teletext (or WST) is the name of a standard for encoding and displaying teletext information, which is used as the standard for teletext throughout Europe today. WST originally stems from the UK standard developed by the BBC and the UK Independent Broadcasting Authority in 1974 for teletext transmission, extended in 1976 as the Broadcast Teletext Specification. With some tweaks to allow for alternative national character sets, and adaptations to the NTSC 525-line system as necessary, this was then promoted internationally as "World System Teletext". It was accepted by CCIR in 1986 under international standard CCIR