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{{Short description|Character or punctuation mark used to represent a duplicated character or word}}
{{More citations needed|date=September 2017}}
[[File:Song ding inscription (cropped).jpg|thumb|upright=0.5|alt=A crop of a rubbing of a bronze bowl shows Chinese characters including a mark to indicate duplication of the preceding character.|Bronzeware script, {{circa|825 BC}}]]

'''Iteration marks''' are characters or punctuation marks that represent a duplicated character or word.

==Chinese==
In [[Chinese language|Chinese]], {{lang|zh|𠄠}}  or {{Unichar|16FE3|Old Chinese Iteration Mark}} (usually appearing as {{lang|zh|〻}}, equivalent to the modern ideograph {{Char|二}}) or {{lang|zh|々}} is used in casual writing to represent a doubled character. However, it is not used in formal writing anymore, and it rarely appeared in printed matter. In a tabulated table or list, vertical repetition can be represented by a [[ditto mark]] ({{lang|zh|〃}}).

===History===
Iteration marks have been occasionally used for more than two thousand years in [[China]]. The example image shows an inscription in [[bronze script]], a variety of formal writing dating to the [[Zhou dynasty]], that ends with {{lang|zh|"子<sub>𠄠</sub>孫<sub>𠄠</sub>寶用"}}, where the small {{lang|zh|𠄠}} ("two") is used as iteration marks in the phrase {{lang|zh|"子子孫孫寶用"}} ("descendants to use and to treasure").

==Malayo-Polynesian languages==
{{see also|Malayo-Polynesian languages}}
In [[Filipino language|Filipino]], [[Indonesian language|Indonesian]], and [[Malay language|Malay]], words that are repeated can be shortened with the use of numeral "2". For example, the Malay {{Transliteration|ms|kata-kata}} ("words", from single {{Transliteration|ms|kata}}) can be shortened to {{Transliteration|ms|kata2}}, and {{Transliteration|ms|jalan-jalan}} ("to walk around", from single {{Transliteration|ms|jalan}}) can be shortened to {{Transliteration|ms|jalan2}}. The usage of "2" can be also replaced with superscript "{{sup|2}}" (e.g. {{Transliteration|ms|kata{{sup|2}}}} for {{Transliteration|ms|kata2}}). The sign may also be used for reduplicated compound words with slight sound changes, for example {{Transliteration|ms|hingar{{sup|2}}}} for {{Transliteration|ms|hingar-bingar}} ("commotion"). Suffixes may be added after "2", for example in the word {{Transliteration|ms|kebarat{{sup|2}}an}} ("Western in nature", from the basic word {{Transliteration|ms|barat}} ("West") with the prefix {{Transliteration|ms|ke-}} and suffix {{Transliteration|ms|-an}}).<ref name="polisieyd">{{cite web |url=http://polisieyd.blogsome.com/dari-ejaan-van-ophuijsen-hingga-eyd/ |archive-url=https://web.archive.org/web/20120130172714/http://polisieyd.blogsome.com/dari-ejaan-van-ophuijsen-hingga-eyd/ |archive-date=2012-01-30 |title=Dari Ejaan van Ophuijsen Hingga EYD |language=id}}</ref>

The use of this mark dates back to the time when these languages were written with [[Arabic script]], specifically the [[Jawi script|Jawi]] or [[pegon script|Pegon]] varieties. Using the Arabic numeral {{lang|ms-Arab|٢}}, words such as {{lang|ms-Arab|رام رام}} ({{Transliteration|ms|rama-rama}}, butterfly) can be shortened to {{lang|ms-Arab|رام٢}}. The use of Arabic numeral {{lang|ms-Arab|٢}} was also adapted to several [[brahmic script|Brahmi]] derived scripts of the Malay archipelago, notably [[Javanese script|Javanese]],<ref name=uni>{{Cite web|url=https://www.unicode.org/L2/L2008/08015r-n3319r3-javanese.pdf|title=L2/08-015R: Proposal for encoding the Javanese script in the UCS|date=2008-03-06|first=Michael|last=Everson|author-link=Michael Everson}}</ref> [[Sundanese language|Sundanese]],<ref name=uni>{{Cite web|url=https://www.unicode.org/L2/L2008/08015r-n3319r3-javanese.pdf|title=L2/08-015R: Proposal for encoding the Javanese script in the UCS|date=2008-03-06|first=Michael|last=Everson|author-link=Michael Everson}}</ref> [[Lontara script|Lontara]],<ref>{{Cite web|url=http://std.dkuug.dk/jtc1/sc2/wg2/docs/n2633r.pdf|title=Proposal for encoding the Lontara script in the UCS|first=Michael|last=Everson|author-link=Michael Everson}}</ref> and Makassaran.<ref>{{cite web | url=https://www.unicode.org/L2/L2015/15233-makasar.pdf | title=L2/15-233: Proposal to encode the Makasar script in Unicode | first=Anshuman | last=Pandey | date=2015-11-02 }}</ref> As the [[Latin alphabet]] was introduced to the region, the Western-style Arabic numeral "2" came to be use for Latin-based orthography.

The use of "2" as an iteration mark was official in Indonesia up to 1972, as part of the [[Republican Spelling System]]. Its usage was discouraged when the [[Enhanced Indonesian Spelling System]] was adopted, and even though it is commonly found in handwriting or old signage, it is considered to be inappropriate for formal writing and documents.<ref name="polisieyd"/>

==Japanese==
Japanese has various iteration marks for its three [[Japanese writing system|writing systems]], namely [[kanji]], [[hiragana]], and [[katakana]], but only the kanji iteration mark ({{lang|ja|々}}) is commonly used today.{{citation needed|date=October 2021}}

In [[Japanese language|Japanese]], iteration marks called {{nihongo3|"dancing mark"|踊り字|odoriji}}, {{nihongo||重ね字|kasaneji}}, {{nihongo||繰り返し記号|kurikaeshikigō}}, or {{nihongo3|"repetition symbols"|反復記号|hanpukukigō}} are used to represent a duplicated character representing the same [[morpheme]]. For example, {{Transliteration|ja|hitobito}}, "people", is usually written {{lang|ja|人々}}, using the kanji for {{lang|ja|人}} with an iteration mark, {{lang|ja|々}}, rather than {{lang|ja|人人}}, using the same kanji twice. The use of two kanji in place of an iteration mark is allowed, and in simple cases may be used due to being easier to write.

In contrast, while {{nihongo3|"daily, day after day"|日々|hibi}} is written with the iteration mark, as the morpheme is duplicated, {{nihongo3|"number of days, date"|日日|hinichi}} is written with the character duplicated, because it represents different morphemes ({{Transliteration|ja|hi}} and {{Transliteration|ja|nichi}}). Further, while {{Transliteration|ja|hibi}} can in principle be written as {{lang|ja|日日}}, {{Transliteration|ja|hinichi}} cannot be written as {{lang|ja|日々}}, since that would imply repetition of the sound as well as the character. In potentially confusing examples such as this, readings can be disambiguated by writing words out in hiragana, so {{Transliteration|ja|hinichi}} is often found as {{lang|ja|日にち}} or {{lang|ja|ひにち}} rather than {{lang|ja|日日}}.

Sound changes can occur in duplication, which is not reflected in writing; examples include {{nihongo||人|hito}} and {{nihongo||人|hito}} being pronounced {{nihongo||人々|hitobito}} ({{Transliteration|ja|[[rendaku]]}}) or {{nihongo||刻|koku}} and {{nihongo||刻|koku}} being pronounced {{nihongo||刻々|kokkoku}} ([[gemination]]), though this is also pronounced {{Transliteration|ja|kokukoku}}.

===Kanji===
[[File:Vertical ideographic iteration mark.svg|thumb|upright=0.3|{{lang|ja|〻}}, an iteration mark (derived from {{lang|ja|𠄠}}) used only in vertical writing.]]

The formal name of the kanji repetition symbol ({{lang|ja|々}}) is {{nihongo||同の字点|dōnojiten}}, literally "same character mark", but it is sometimes called {{nihongo||のま|noma}} because it looks like the katakana {{nihongo||ノ|no}} and {{nihongo||マ|ma}}. This symbol originates from a simplified form of the character {{lang|ja|[[wikt:仝|仝]]}}, a variant of {{nihongo3|"same"|[[wikt:同|同]]}} written in the [[Cursive script (East Asia)|grass script]] style.<ref>{{cite web |url=http://kanjibunka.com/kanji-faq/old-faq/q0009/ |script-title=ja:漢字文化資料館 漢字Q&A〈旧版〉 Q0009 「々」はなんと読むのですか？ |language=ja}}</ref>

Although Japanese kanji iteration marks are borrowed from [[#Chinese|Chinese]], the grammatical function of duplication differs, as do the conventions on the use of these characters.

While Japanese does not have a grammatical [[plural]] form ''per se'', some kanji can be [[reduplication|reduplicated]] to indicate plurality (as a collective noun, not many individuals). This differs from Chinese, which normally repeats characters only for the purposes of adding emphasis, although there are some exceptions (e.g., {{lang|zh|人}}, {{Transliteration|zh|rén}}, "person"; {{lang|zh|人人}}, {{Transliteration|zh|rénrén}}, "everybody").
* {{nihongo3|person|人|hito}}; {{nihongo3|people (not "persons")|人々|hitobito}}
* {{nihongo3|mountain|山|yama}}; {{nihongo3|many mountains|山々|yamayama}}

However, for some words duplication may alter the meaning:
* {{nihongo3|piece, object|個|ko}}; {{nihongo3|piece by piece; individually|個々|koko}}
* {{nihongo3|time|時|toki}}; {{nihongo3|sometimes|時々|tokidoki}}
* {{nihongo3|next day|翌日|yokujitsu}}; {{nihongo3|lit. "next next day" (two days later)|翌々日|yokuyokujitsu}}

Using {{lang|ja|々}} instead of repeating kanji is usually the preferred form, with two restrictions:
* the reading must be the same, possibly with sound change (as above), and
* the repetition must be within a single word.

When the reading is different, the second kanji is often simply written out to avoid confusion. Examples of such include:
* {{nihongo||日日 日にち|hinichi}}
* {{nihongo||湯湯婆 湯たんぽ|yutanpo}}
* {{nihongo||出出し 出だし|dedashi}}

The repetition mark is not used in every case where two identical characters appear side by side, but only where the repetition itself is etymologically significant—when the repetition is part of a single word. Where a character ends up appearing twice as part of a compound, it is usually written out in full:

* {{nihongo3|"democracy"|民主主義|minshu-shugi}}, from {{lang|ja|民主}} + {{lang|ja|主義}} ("democracy" + "principle"); the abbreviated {{lang|ja|民主々義}} is only occasionally seen. One notable exception is in signs for {{Nihongo|neighborhood associations|町内会|chōnaikai}} – the name of neighborhoods often end in {{Nihongo|"... neighborhood"|〜町|-chō}}, which is then suffixed with {{lang|ja|〜町内会}} yielding {{Nihongo|"... neighborhood neighborhood association"|〜町町内会|-chō-chōnaikai}}, which is then informally abbreviated to {{lang|ja|〜町々内会}}, despite the word break.

Similarly, in certain Chinese borrowings, it is generally preferred to write out both characters, as in {{lang|ja|九九}} ({{Transliteration|ja|ku-ku}} [[Chinese multiplication table]]) or {{lang|ja|担担麺}} ({{Transliteration|ja|tan-tan-men}} [[dan dan noodles]]), though in practice {{lang|ja|々}} is often used.

In [[tategaki|vertical writing]], the character {{lang|ja|〻}} ([[Unicode]] U+303B), a cursive derivative of {{lang|ja|𠄠}} ("two", as in [[#Chinese|Chinese]], above), can be employed instead, although this is increasingly rare.

===Kana===
[[Kana]] uses different iteration marks; one for hiragana, {{lang|ja|ゝ}}, and one for katakana, {{lang|ja|ヽ}}. The hiragana iteration mark is seen in some personal names like {{lang|ja|さゝき}} {{Transliteration|ja|Sasaki}} or {{lang|ja|おゝの}} {{Transliteration|ja|Ōno}}, and it forms part of the formal name of the car company {{nihongo3||いすゞ|[[Isuzu]]}}.

Unlike the kanji iteration marks, which do not reflect sound changes, kana iteration marks closely reflect sound, and the kana iteration marks can be combined with the {{Transliteration|ja|dakuten}} voicing mark to indicate that the repeated syllable should be voiced, for example {{lang|ja|みすゞ}} {{Transliteration|ja|Misuzu}}. If the first syllable is already voiced, for example {{lang|ja|じじ}} {{Transliteration|ja|jiji}}, the voiced repetition mark still needs to be used: {{lang|ja|じゞ}} rather than {{lang|ja|じゝ}}, which would be read as {{Transliteration|ja|jishi}}.

While widespread in old Japanese texts, the kana iteration marks are generally not used in modern Japanese outside proper names, though they may appear in informal handwritten texts.

===Repeating multiple characters===
[[Image:IterationMarks600.jpg|thumb|right|A variety of iteration marks in use in the classical text {{nihongo||徒然草|[[Tsurezuregusa]]}} {{lang|ja|「世に語り傳ふる事–げにげにしく所々うちおぼめき–また疑ひ嘲るべからず」}} (73rd passage)]]

In addition to the single-character iteration marks, there are also two-character-sized '''repeat marks''', which are used to repeat the preceding word or phrase. They are used in [[Horizontal and vertical writing in East Asian scripts|vertical writing]] only, and they are effectively obsolete in modern Japanese. The vertical kana repeat marks {{lang|ja|〱}} (unvoiced) and {{lang|ja|〲}} (voiced) resemble the hiragana character {{nihongo||く|ku}}, giving them their name, {{nihongo||くの字点|kunojiten}}. They stretch to fill the space typically occupied by two characters, but may indicate a repetition of more than two characters. For example, the duplicated phrase {{lang|ja|何とした何とした}} may be repeated as {{lang|ja|何とした〱}}. If a {{Transliteration|ja|dakuten}} (voiced mark) is added, it applies to the first sound of the repeated word; this is written as {{lang|ja|〲}}. For example, {{Transliteration|ja|tokorodokoro}} could be written horizontally as {{lang|ja|ところ〲}}; the voiced iteration mark only applies to the first sound {{lang|ja|と}}.

In addition to the single-character representations {{unichar|3031|VERTICAL KANA REPEAT MARK}} and {{unichar|3032|VERTICAL KANA REPEAT WITH VOICED SOUND MARK}}, [[Unicode]] provides the half-character versions {{unichar|3033|VERTICAL KANA REPEAT MARK UPPER HALF}}, {{unichar|3034|VERTICAL KANA REPEAT WITH VOICED SOUND MARK UPPER HALF}} and {{unichar|3035|VERTICAL KANA REPEAT MARK LOWER HALF}}, which can be stacked to render both voiced and unvoiced repeat marks:

{| lang="ja" style="padding-left: 3em"
| <div style='border:0;padding:0;font-size:15px;'><div style='height:1em;'>〳</div><div style='height:1em;'>〵</div></div> || <div style='border:0;padding:0;font-size:15px;'><div style='height:1em;'>〴</div><div style='height:1em;'>〵</div></div>
|}

As support for these is limited, the ordinary forward slash {{lang|ja|／}} and backward slash {{lang|ja|＼}} are occasionally used as substitutes.

Alternatively, multiple single-character iteration marks can be used, as in {{nihongo||ところゞゝゝ|tokorodokoro}} or {{nihongo||馬鹿々々しい|bakabakashii}}. This practice is also uncommon in modern writing, though it is occasionally seen in horizontal writing as a substitute for the vertical repeat mark.{{dubious|date=July 2024}}

Unlike the single-kana iteration mark, if the first kana is voiced, the unvoiced version {{lang|ja|〱}} alone will repeat the voiced sound.

Further, if {{Transliteration|ja|[[okurigana]]}} are present, then no iteration mark should be used, as in {{lang|ja|休み休み}}. This is prescribed by the Japanese Ministry of Education in its 1981 Cabinet notification prescribes, rule #6.{{citation needed|date=March 2022}}

==Nuosu==

In the [[Yi language|Nuosu language]], {{lang|ii|ꀕ}} is used to represent a doubled sound, for example {{lang|ii|ꈀꎭꀕ}}, {{Transliteration|ii|kax sha sha}}. It is used in all forms of writing.

==Tangut==
{{Contains special characters|Tangut|section}}
In [[Tangut script|Tangut]] manuscripts the sign {{Tangut|𖿠}} is sometimes used to represent a doubled character; this sign does not occur in printed texts. In [[Unicode]] this character is {{mono|U+16FE0}} {{smallcaps all|TANGUT ITERATION MARK}}, in the [[Ideographic Symbols and Punctuation]] block.

==Egyptian hieroglyphs==
In [[Egyptian hieroglyphs]], the signs: <hiero>zp:Z1*Z1</hiero> &nbsp; &mdash; &nbsp; {{Transliteration|egy|[[wikt:zpwj snwj|zp(wj) sn(wj)]]}}, literally meaning "two times", repeat the previous sign or word.

==Khmer, Thai and Lao==
In [[Khmer script|Khmer]], {{Transliteration|km|leiktō}} ({{lang|km|[[wikt:ៗ|ៗ]]}}) as for [[Thai alphabet|Thai]], {{Transliteration|th|mai yamok}} ({{lang|th|[[wikt:ๆ|ๆ]]}}) and [[Lao script|Lao]], {{Transliteration|lo|ko la}} ({{lang|lo|[[wikt:ໆ|ໆ]]}}) represent a repeated syllable where as it besides the word. This used to be written as numeral two ({{lang|km|២}}) and the form changed over time. A repeated word could be used either, to demonstrate plurality, to emphasize or to soften the meaning of the original word.

== Ditto mark ==
{{main|Ditto mark}}
In [[English language|English]], [[Spanish language|Spanish]], [[French language|French]], [[Italian language|Italian]], [[German language|German]], [[Portuguese language|Portuguese]], [[Czech language|Czech]], [[Polish language|Polish]] and [[Turkish language|Turkish]] lists, the [[ditto mark]] (″) represents a word repeated from the equivalent position in the line above it; or an evenly-spaced row of ditto marks represents any number of words repeated from above. For example:

* Two pounds of lettuce
* Three&nbsp;&nbsp; ″&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;    ″  tomatoes
* Four&nbsp;&nbsp;&nbsp;&nbsp;  ″&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;″ onions
* One pound&nbsp;    ″ carrots

This is common in handwriting and formerly in typewritten texts.

In [[Unicode]], the [[ditto mark]] of [[Western world|Western languages]] has been defined to be equivalent to the {{unichar|2033|double prime|html=|nlink=Double prime}}.{{citation needed|date=July 2019|reason=Different Western languages have different typographic requirements, it might be ”, „, or even ». Double prime ″ U+2033 is cross referenced from 〃 U+3003 in the Code Charts only because it has similar shape to the CJK ditto mark}} The separate character {{unichar|3003|ditto mark|html=}} is to be used in the [[CJK characters|CJK scripts]] only.<ref>{{cite web|title=Unicode Standard Annex #24: Unicode Script Property |url=https://www.unicode.org/reports/tr24/tr24-19.html#Script_Extensions|at=2.9 Script_Extensions Property|access-date=2013-05-19}}</ref><ref>{{cite web|url=https://www.unicode.org/Public/6.2.0/ucd/ScriptExtensions.txt|title=ScriptExtensions.txt|access-date=2013-05-19}}</ref><ref>{{cite web|url=https://www.unicode.org/charts/PDF/U3000.pdf|title=CJK symbols and Punctuation|access-date=2013-05-20}}</ref>

The convention in Polish handwriting, Czech, [[Swedish language|Swedish]], and Austrian German is to use a ditto mark on the baseline together with horizontal lines spanning the extent of the word repeated, for example:
* {{lang|pl|Dwa kilogramy pomidorów}}
* {{lang|pl|Trzy  — „ —  cebuli}}
* {{lang|pl|Cztery — „ —  ziemniaków}}

== Superscript numeral ==

In western mathematics, the superscript numeral originated as a notation for exponentiation.<ref>{{cite book |last1=Cajori |first1=F |title=A History of Mathematical Notation Vol. 1 |date=1928 |publisher=The Open Court Publishing Company |location=La Salle, Illinois |page=346}}</ref> Over time its meaning expanded to represent repeated function application as well, effectively making it a notation for marking iteration.<ref>{{cite book |last1=Cajori |first1=F |title=A History of Mathematical Notation Vol. 2 |date=1929 |publisher=The Open Court Publishing Company |location=La Salle, Illinois |page=176}}</ref> This sense was eventually borrowed in non mathematical text to represent repeated symbols, especially to mark repeated letters in acronyms. The superscript is occasionally left out, either colloquially or in the formal representation of the acronym, due to either typographic or stylistic concerns. Notable examples include the bus protocol [[I²C]], and the fan-fiction hosting website [[AO3]].

== See also ==
*[[Japanese typographic symbols]]

== References ==
{{reflist}}

==External links==
* {{Commons category-inline|Iteration mark}}

[[Category:Punctuation]]
[[Category:East Asian typography]]
[[Category:Kana]]
[[Category:Kanji]]