Obelus

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For the genus of snails, see Obelus (gastropod).

Three variants of obelus glyphs
÷ † ⁒ ⸓
Modern forms of the obelus
In 
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An obelus (plural: obeluses or obeli) is a term in codicology and latterly in typography that refers to a historical annotation mark which has resolved to three modern meanings:

The word "obelus" comes from ὀβελός (obelós), the Ancient Greek word for a sharpened stick, spit, or pointed pillar.[1] This is the same root as that of the word 'obelisk'.[2]

In mathematics, the first symbol is mainly used in

footnote indicator.[6] It also has other uses
in a variety of specialist contexts.

Use in text annotation

See also: Obelism
Further information:
Dagger (typography)

The modern dagger symbol originated from a variant of the obelus, originally depicted by a plain line −, or a line with one or two dots ⨪ ÷.[7] It represented an iron roasting spit, a dart, or the sharp end of a javelin,[8] symbolizing the skewering or cutting out of dubious matter.[9]

Originally, one of these marks (or a plain line) was used in ancient manuscripts to mark passages that were suspected of being corrupted or spurious; the practice of adding such marginal notes became known as

dagger symbol †, also called an obelisk,[10]
is derived from the obelus, and continues to be used for this purpose.

The obelus is believed to have been invented by the

Homeric epics.[9] The system was further refined by his student Aristophanes of Byzantium, who first introduced the asterisk and used a symbol resembling a ⊤ for an obelus; and finally by Aristophanes' student, in turn, Aristarchus, from whom they earned the name of "Aristarchian symbols".[11][12]

In some commercial and financial documents, especially in Germany and Scandinavia, a variant (U+2052 ⁒

COMMERCIAL MINUS SIGN) is used in the margins of letters to indicate an enclosure, where the upper point is sometimes replaced with the corresponding number.[13]
In Finland, the obelus (or a slight variant, ) is used as a symbol for a correct response (alongside the check mark, ✓, which is used for an incorrect response).[14][15]

In the 7.0 release of Unicode, U+2E13 ⸓ DOTTED OBELOS was one of a group of "Ancient Greek textual symbols" that were added to the specification (in the block Supplemental Punctuation).[16]

In mathematics

Main article: Division sign
Plus and minuses. The obelus – or division sign – used as a variant of the minus sign in an excerpt from an official Norwegian trading statement form called «Næringsoppgave 1» for the taxation year 2010.

The form of the obelus as a horizontal line with a dot above and a dot below, ÷, was first used as a symbol for

fraction bar for division, or the colon : for ratios; it says that ÷ "should not be used" for division.[19]

This form of the obelus was also occasionally used as a mathematical symbol for subtraction in Northern Europe; such usage continued in some parts of Europe (including Norway and, until fairly recently, Denmark).[20] In Italy, Poland and Russia, this notation is sometimes used in engineering to denote a range of values.[21]

In some commercial and financial documents, especially in Germany and Scandinavia, another form of the obelus – the commercial minus sign – is used to signify a negative remainder of a division operation.[22][14]

See also

References

  1. ^ R. E. Allen, ed. (1993). The Concise Oxford Dictionary. p. 817.
  2. ^ R. E. Allen, ed. (1993). The Concise Oxford Dictionary. p. 816.
  3. ^ Weisstein, Eric W. "Division". mathworld.wolfram.com. Retrieved 2020-08-26.
  4. ISBN 9781400857692
    .
  5. ISBN 9780191073014
    .
  6. ISBN 9788186062258
    .
  7. ISBN 978-0-87779-809-5
    . obelos.
  8. ^ William Harrison Ainsworth, ed. (1862). The New monthly magazine. Vol. 125. Chapman and Hall. p. 1.
  9. ^
    ISBN 978-3-16-146575-8
    .
  10. ^ "Dagger (8)". The Oxford English Dictionary (D–E. 1933. p. 7.
  11. ISBN 978-0-19-814747-3
    .
  12. ISBN 978-0-87220-310-5
    .
  13. ISBN 978-1-936213-16-0
    .
  14. ^ a b Leif Halvard Silli. "Commercial minus as italic variant of division sign in German and Scandinavian context". Unicode.org. Archived from the original on 2019-06-14. Retrieved 2020-04-04.
  15. ^ "6. Writing Systems and Punctuation". The Unicode® Standard: Version 10.0 – Core Specification (PDF). Unicode Consortium. June 2017. p. 280, Commercial minus.
  16. ^ "Supplemental Punctuation" (PDF). Unicode Consortium. 2014.
  17. ^ "Math Words". Math Words Alphabetical Index. p. 7. Archived from the original on August 7, 2011. Retrieved August 26, 2011.
  18. ^ "Division". www.mathsisfun.com. Retrieved 2020-08-26.
  19. ISO 80000-2
    , Section 9 "Operations", 2-9.6
  20. ISBN 9780486677668
    . Reprint of 1928 edition.
  21. ^ "6. Writing Systems and Punctuation". The Unicode® Standard: Version 10.0 – Core Specification (PDF). Unicode Consortium. June 2017. p. 280, Obelus.
  22. ^ Johann Philipp Schellenberg (1825). Kaufmännische Arithmetik oder allgemeines Rechenbuch für Banquiers, Kaufleute, Manufakturisten, Fabrikanten und deren Zöglinge [Commercial arithmetic or general arithmetic book for bankers, merchants, manufacturers, craftsmen and their pupils] (in German). p. 213.
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