Editing Viewdata (section)

== Design ==

Viewdata offered a display of 40×24 characters, based on [[ISO 646]] (IRV IA5) – 7 bits with no accented characters.<ref name=aei>{{cite web| url=http://aei.pitt.edu/94572/1/videotex.pdf | title=Proceedings of the Videotex in Europe | access-date=2023-12-26 | date=1979-07-19}}</ref>
Originally, Viewdata was accessed with a special purpose [[Computer terminal|terminal]] (or [[Emulator|emulation software]]) and a [[modem]] running at [[ITU-T]] [[ITU-T V.23|V.23]] speed (1,200 bit/s down, 75 bit/s up).<ref name=aei/> By 2004, it was normally accessed over [[TCP/IP]] using Viewdata [[client software]] on a [[personal computer]] running [[Microsoft Windows]], or using a Web-based emulator.

{{Infobox symbol
|name= Viewdata keypad symbols
|mark=⌗ ⚹
|unicode={{unichar|2317||html=}}<br /> {{unichar|26B9|html=|nlink=}}
|see also= 
|different from={{unichar|002A|html= | nlink= }}<br />{{unichar|0023|html= | nlink=}}
}}
[[File:Detail-Tastatur-FeTAp-751-1982.JPG |thumb|left|Detail of a telephone keypad displaying the sextile and Viewdata square]]
[[File:AVAYA 9611G IP Phone detail of star and hash.jpg |thumb|left|Detail of a more recent telephone keypad, in which (typographic) asterisk and number{{nbsp}}sign have replaced the ITU star and square]]

Viewdata uses special symbols already widely available on telephone keypads: the {{key press|⚹}} "star" key and the {{key press|⌗}} "square" key, as formally standardised by the [[International Telecommunication Union]].<ref>{{cite web | url =  http://www.itu.int/rec/T-REC-E.161-200102-I/en | title = E.161 : Arrangement of digits, letters and symbols on telephones and other devices that can be used for gaining access to a telephone network | publisher = [[International Telecommunication Union]] | date= 2 February 2001 | access-date =  23 December 2019}}</ref> 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.<ref name="L213105r" />

These symbols appear as 'Sextile' and 'Viewdata square' in the [[Miscellaneous Symbols]] and [[Miscellaneous Technical]] Unicode blocks, respectively. The sextile was added due to [[Astrological aspect|its use in astrology]],<ref name="L213105r">{{cite web|url=https://unicode.org/L2/L2013/13105r-telephony.pdf |archive-url=https://ghostarchive.org/archive/20221009/https://unicode.org/L2/L2013/13105r-telephony.pdf |archive-date=2022-10-09 |url-status=live | title= Proposal to incorporate two telephony symbols into Unicode by glyph and annotation changes | date= 28 October 2013 | access-date =  23 December 2019 | author = Karl Pentzlin |id=UTC L2/13-105R}}</ref> and the square had previously appeared in the [[ISO/IEC 646#Variant comparison chart|BS_Viewdata]] character set, as a replacement for the underscore.<ref name="ISO-IR-047">{{cite iso-ir |title=Alphanumerics for viewdata and broadcast teletext |sponsor=BSI |sponsor-link=BSI Group |date=1981-06-01 |number=47}}</ref>

In 2013, the German national body submitted a [[Unicode Consortium|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.<ref name="L213105r" /> {{as of|2019}} (Unicode 12.1), these changes have not been accepted/implemented.<ref>{{cite web |url=https://www.unicode.org/charts/PDF/U2300.pdf |archive-url=https://ghostarchive.org/archive/20221009/https://www.unicode.org/charts/PDF/U2300.pdf |archive-date=2022-10-09 |url-status=live |title=Miscellaneous Technical |work=The Unicode Standard |author=Unicode Consortium |author-link=Unicode Consortium}}</ref>