page_title: Viewdata
section_title: Viewdata keypad symbols: the square and the sextile
hierarchical_section_title: Viewdata / Viewdata keypad symbols: the square and the sextile
caption_attribution_description: English: Detail of keypad with # as the hash key (contrast File:Detail-Tastatur-FeTAp-751-1982.JPG with a style of ⌗ not readily recognisable as a #)
context_page_description: Viewdata is a Videotex implementation. It is a type of information retrieval service in which a subscriber can access a remote database via a common carrier channel, request data and receive requested data on a video display over a separate channel. Samuel Fedida, who had the idea for Viewdata in 1968, was credited as inventor of the system. The first prototype became operational in 1974. The access, request and reception are usually via common carrier broadcast channels. This is in contrast with teletext.
context_section_description: Viewdata uses special symbols already widely available on telephone keypads: "star" key and the "square" key, as formally standardised by the International Telecommunications Union. These are often treated as approximately corresponding to the ASCII asterisk (*) and number sign (#), which do not necessarily conform to the ITU specifications for the keypad symbols; the asterisk is also usually displayed smaller and raised.
  These symbols appear as 'Sextile' and 'Viewdata square' in the Miscellaneous Symbols and Miscellaneous Technical Unicode blocks, respectively. The sextile was added due to its use in astrology, and the square had previously appeared in the BS_Viewdata character set, as a replacement for the underscore.
  In 2013, the German national body submitted a Unicode Technical Committee proposal to align the Unicode reference glyphs with the ITU specifications for these symbols, and annotate them as telephone keypad symbols on the code charts. As of 2019 (Unicode 12.1), these changes have not been accepted/implemented.
caption: Detail of a telephone keypad substituting # and an enlarged *
exif: {}