Enhanced UK teletext level 4 aphageometrics

The UK teletext system, based on a rugged fixed-format concept has proved itself to be an inexpensive and effective means of data broadcasting. In spite of this, there has been recent pressure to make available a greater degree of sophistication, in order to provide facilities at least equivalent to those of subsequently proposed alternative teletext systems. The response has been to develop a range of compatible enhancements, leading to the identification of five teletext `levels¿, the highest of which (alphaphotographics) is believed to be well in advance of any other data broadcasting proposal. In this short review, an outline of these levels is followed by a brief description of the level 4 alphageometric enhancements pioneered by the IBA, as it is in this particular area that the alternative systems most strongly allege their superiority.