An interpunct ( · ), also called an interpoint, is a punctuation mark consisting of a dot used for interword separation in ancient Latin script and in some modern languages as a stand-alone sign inside a word. It is present in Unicode as code point U+00B7 · middle dot (HTML:
The dot is vertically centered, e.g. "DONA·EIS·REQVIEM", and is therefore also called a middle dot or centered dot (Commonwealth: centred dot). In addition to the round dot form, inscriptions sometimes use a small equilateral triangle for the interpunct, pointing either up or down. Such triangles can be found on inscriptions on buildings in the twentieth century. Ancient Greek, by contrast, had not developed interpuncts; all the letters ran together. The use of spaces for word separation did not appear until much later, some time between 600 and 800 AD.
The multiplication dot (U+2219 ∙ bullet operator (HTML:
∙) or U+22C5 ⋅ dot operator (HTML:
⋅), whose glyphs are similar or identical to the interpunct's) is a multiplication sign (instead of the × often used in English-speaking countries): "a multiplied by b" is written either as a⋅b or using juxtaposition as ab, depending on context. It also discriminates the scalar product (a ⋅ b) from the vector cross product (a × b) or exterior product (a ∧ b) in vector multiplication. As a multiplication operator, it is one of the standard stylings (the other being simply a space) of symbols for compound units such as the newton metre (N∙m or N m), although in practice these unit symbols are often written with interpunct or the bullet as in a bulleted list (•) (U+2022 • bullet (HTML:
•)) (just as many people use the masculine ordinal indicator [º] where a degree sign [°] ought to be).
In written language
Various dictionaries often use the interpunct (in this context, sometimes called hyphenation point) to indicate syllabification within a word with multiple syllables.
In British typography, an interpunct is sometimes called a space dot. Traditionally it has been primarily used as a decimal point, e.g. 3·14 as opposed to the SI formats 3.14 and 3,14, but this usage is less common in typography than in handwritten text, as a full stop (period) is easier to type.
In British publications up to the mid-1970s, especially scientific and mathematical texts, the decimal point was commonly typeset as a middle dot. When the British currency was decimalized in 1971, the official advice issued was to write decimal amounts with a raised point (thus: £21·48) and to use a decimal point "on the line" only when typesetting constraints made it unavoidable. The widespread introduction of electronic typewriters and calculators (many of which were manufactured and imported from places like Japan and the United States) soon afterwards was probably a major factor contributing to the decline of the raised decimal point, although it can still sometimes be encountered in academic circles (e.g., Cambridge University History Faculty Style Guide 2010) and its use is still enforced by some UK-based academic journals such as The Lancet.
In the Shavian alphabet of English, the middle dot is used before a word to denote it as a proper noun.
In Catalan, the punt volat (literally, "flown dot") is used between two 〈l〉 (thus: 〈l·l〉) in cases where each belongs to a separate syllable (e.g. cel·la, 'cell'). This is to distinguish the true "double-l" pronunciation [ɫː] from that of the letter-combination 〈ll〉 (without a dot) which in Catalan stands for [ʎ] (e.g. cella, 'eyebrow').
In orthographic descriptions, 〈l·l〉 is called ela geminada ("geminate l") and 〈ll〉 doble ela. A period or a hyphen is frequently used when a middle dot is unavailable: col.lecció or col-lecció. This is nonetheless considered a misspelling. Unicode has unique code points for the letters 〈Ŀ〉 (U+013F) and 〈ŀ〉 (U+0140), but they are compatibility characters and are not frequently used nor recommended. The preferred Unicode representation is 〈l·〉 (U+006C + U+00B7). The use of the 〈•〉 bullet (U+2022,
•) is strongly discouraged on aesthetic grounds.
There is no separate keyboard layout for Catalan; punt volat can be typed using Shift-3 in the Spanish (Spain) layout.
The Chinese language sometimes uses the interpunct (called the partition sign) to separate the given name and the family name of non-Chinese, or unsinicized or desinicized minority ethnic groups in China, for example, 威廉·莎士比亚 (Wēilián·Shāshìbǐyǎ) is the transliteration of "William Shakespeare", and the partition sign is inserted in between the characters signifying the sound of "William" and those for "Shakespeare". In Taiwan the Unicode code point U+2027, Hyphenation Point, is recommended by government as a fullwidth punctuation to separate the given name and the family name of non-Chinese. Therefore 威廉‧莎士比亞 is the transliteration of "William Shakespeare" (traditional Chinese). The Chinese partition sign is also used to separate book title and chapter title when they are mentioned consecutively (with book title first, then chapter).
In Chinese, the middle dot is also fullwidth in printed matter, but the regular middle dot (·) is used in computer input, which is then rendered as fullwidth in Chinese-language fonts. Note that while some fonts may render the Japanese katakana middle dot as a square under great magnification, this is not a defining property of the middle dot that is used in China or Japan.
See also proper name mark.
In Pe̍h-ōe-jī for Taiwanese Hokkien, middle dot is often used as a workaround for dot above right diacritic because most early encoding systems did not support this diacritic. This is now encoded as U+0358 ͘ combining dot above right (see o͘). Unicode did not support this diacritic until June 2004. Newer fonts often support it natively; however, the practice of using middle dot still exists. Historically, it was derived in the late 19th century from an older barred-o with curly tail as an adaptation to the typewriter.
In Franco-Provençal (or Arpitan), the interpunct is used in order to distinguish the following graphemes:
- ch·, pronounced [ʃ], versus ch, pronounced [ts]
- j·, pronounced [ʒ], versus j, pronounced [dz]
- g· before e, i, pronounced [ʒ], versus g before e, i, pronounced [dz]
The Greek ánō stigmē or ánō teleía (άνω στιγμή/άνω τελεία, lit. "upper dot") is a punctuation mark equivalent to the semicolon and is often incorrectly expressed as a middle dot; Unicode provides a unique code point: U+0387 · greek ano teleia.
Interpuncts are often used to separate transcribed foreign words written in katakana. For example, "Can't Buy Me Love" becomes 「キャント・バイ・ミー・ラヴ」 (Kyanto·bai·mī·ravu). A middle dot is also sometimes used to separate lists in Japanese instead of the Japanese comma ("、" known as tōten). Dictionaries and grammar lessons in Japanese sometimes also use a similar symbol to separate a verb suffix from its root.
In Japanese typography, there exist two Unicode code points:
- U+30FB ・ katakana middle dot, with a fixed width that is the same as most kana characters, known as fullwidth.
- U+FF65 ･ halfwidth katakana middle dot
The interpunct also has a number of other uses in Japanese, including the following: to separate titles, names and positions: 課長補佐・鈴木 (Assistant Section Head Suzuki); as a decimal point when writing numbers in kanji: 三・一四一五九二 (3.141 592); and in place of hyphens, dashes and colons when writing vertically.
Interpuncts are used in written Korean to denote a list of two or more words, more or less in the same way a slash (/) is used to juxtapose words in many other languages. In this role it also functions in a similar way to the English en dash, as in 미·소관계, "American–Soviet relations". The use of interpuncts has declined in years of digital typography and especially in place of slashes, but, in the strictest sense, a slash cannot replace a middle dot in Korean typography.
The dot called interpunct was regularly used in classical Latin to separate words. It often took the shape of a triangle, point down, and sometimes of a mid-line comma. It fell out of use circa 200 CE, and Latin was written scripta continua for several centuries.
- s·h, pronounced [s.h], versus sh, pronounced [ʃ], for example, in des·har 'to undo' vs deishar 'to leave'
- n·h, pronounced [n.h], versus nh, pronounced [ɲ], for example in in·hèrn 'hell' vs vinha 'vineyard'
In Old Occitan, the symbol · was sometimes used to denote certain elisions, much like the modern apostrophe, the only difference being that the word that gets to be elided is always placed after the interpunct, the word before ending either in a vowel sound or the letter n:
- que·l (que lo, that the) versus qu'el (that he)
- From Bertran de Born's Ab joi mou lo vers e·l comens (translated by James H. Donalson):
Bela Domna·l vostre cors gens
Domna·l [ˈdonnal] = Domna, lo ("Lady, the": singular definite article)
O pretty lady, all your grace
In many linguistic works discussing Old Irish (but not in actual Old Irish manuscripts), the interpunct is used to separate a pretonic preverbal element from the stressed syllable of the verb, e.g. do·beir "says". It is also used in citing the verb forms used after such preverbal elements (the prototonic forms), e.g. ·beir "carries", to distinguish them from forms used without preverbs, e.g. beirid "carries". In other works, the hyphen (do-beir, -beir) or colon (do:beir, :beir) may be used for this purpose.
Runic texts use either an interpunct-like or a colon-like punctuation mark to separate words. There are two Unicode characters dedicated for this: U+16EB ᛫ runic single punctuation and U+16EC ᛬ runic multiple punctuation.
In mathematics and science
In mathematics, a small middle dot can be used to represent product; for example, x ∙ y for the product of x and y. When dealing with scalars, it is interchangeable with the multiplication sign: x ⋅ y means the same thing as x × y, but × is easily confused with the letter x. However, when dealing with vectors, the dot product is distinct from the cross product. This usage has its own designated code point in Unicode, U+2219 (∙), called the "bullet operator". It is also sometimes used to denote the “AND” relationship in formal logic, due to the relationship between these two operations. In situations where the interpunct is used as a decimal point (as noted above, by many mathematics teachers in some countries[weasel words]), then the multiplication sign used is usually a full stop (period), not an interpunct.
In computing, the middle dot is usually used to indicate white space in various software applications such as word processing, graphic design, web layout, desktop publishing or software development programs. In some word processors, interpuncts are used to denote not only hard space or space characters, but also sometimes used to indicate a space when put in paragraph format to show indentations and spaces. This allows the user to see where white space is located in the document and what sizes of white space are used, since normally white space is invisible so tabs, spaces, non-breaking spaces and such are indistinguishable from one another.
On computers, the interpunct may be available through various key combinations, depending on the operating system and the keyboard layout. Assuming a QWERTY keyboard layout: on OS X, an interpunct can be entered by pressing ⌥ Opt+⇧ Shift+9; in the X Window System, it can be input by pressing AltGr+.; on Microsoft Windows, it can be inserted by pressing ⎇ Alt+0183 (on the numeric keypad).
|Symbol||Character Entity||Numeric Entity||Unicode Code Point||LaTeX||Notes|
||U+00B7 middle dot||
||U+0387 greek ano teleia||Greek ánō stigmē|
||U+05BC hebrew point dagesh or mappiq||Hebrew point dagesh or mapiq|
||U+16EB runic single punctuation||Runic punctuation|
||U+2022 bullet||bullet, often used to mark list items|
||U+2027 hyphenation point||
||hyphenation point (dictionaries)|
||U+2218 ring operator||
||ring operator (mathematics)|
||U+2219 bullet operator||
||bullet operator (mathematics)|
||U+22C5 dot operator||
||dot operator (mathematics)|
||U+25E6 white bullet||hollow bullet|
||U+2981 z notation spot||symbol used by the Z notation|
||U+2E30 ring point||Avestan punctuation mark|
||U+2E31 word separator middle dot||Word separator (Avestan and other scripts)|
||U+30FB katakana middle dot||fullwidth katakana middle dot|
||U+FF65 halfwidth katakana middle dot||halfwidth katakana middle dot|
||U+10101 aegean word separator dot||Word separator for Aegean scripts (Linear A and Linear B)|
Characters in the Symbol column above may not render correctly in all browsers.
- "Catich, Edward. ''The Origin of the Serif: Brush Writing and Roman Letters.'' Des Moines, Iowa: Saint Ambrose University Catich Gallery, 1991". Amazon.com. Retrieved 2011-01-10.
- Yet there is also a separate Unicode character with the name hyphenation point, code point U+2027.
- "Cambridge University History Faculty Style Guide 2010" (PDF). Retrieved 2011-01-10.
- "Artwork Guidelines for the Lancet" (PDF). Retrieved 2009-01-16.
- Unicode Latin Extended A code chart p.13
- 威廉·莎士比亚 — Google Translate (text to speech).
- "CNS11643 中文全字庫-字碼查詢與下載" (in (Chinese)). Cns11643.gov.tw. Retrieved 2013-04-22.
- "Thesaurus Linguae Graecae". www.tlg.uci.edu. Retrieved 2011-01-10.
- Unicode Greek code chart, pp. 34, 36
- Thurneysen, Rudolf (1946/1980). A Grammar of Old Irish. trans. D. A. Binchy and Osborn Bergin. Dublin Institute for Advanced Studies. p. 25. ISBN 1-85500-161-6.
- Scott Pakin (2009-11-09). "The Comprehensive LATEX Symbol List" (PDF) (in English). Retrieved 2013-02-04.
- Jonathan P. Bowen. "Glossary of Z notation" (PDF). University of Reading (UK) (in English). Retrieved 2013-02-04.
- Deborah Anderson, Michael Everson (2001-10-03). "N2378: Final proposal to encode Aegean scripts in the UCS" (PDF, 0,15 MB). ISO/IEC JTC1/SC2/WG2 (in English). Retrieved 2013-02-04.