Two dots (diacritic)

"Tréma" redirects here. For other uses, seeTrema.

◌̈ ◌̤
Two dots
U+0308◌̈COMBINING DIAERESIS U+0324◌̤COMBINING DIAERESIS BELOW U+07F3߳NKO COMBINING DOUBLE DOT ABOVE

Diacritical marksoftwo dots¨,placed side-by-side over or under a letter, are used in several languages for several different purposes. The most familiar toEnglish-languagespeakers are thediaeresisand theumlaut,though there are numerous others. For example, inAlbanian,ërepresents aschwa.Such diacritics are also sometimes used for stylistic reasons (as in the family nameBrontëor the band nameMötley Crüe).

In modern computer systems usingUnicode,the two-dot diacritics are almost alwaysencodedidentically, having the samecode point.For example,U+00F6öLATIN SMALL LETTER O WITH DIAERESISrepresents botho-umlautando-diaeresis.Their appearance in print or on screen may vary betweentypefacesbut rarely within the same typeface.

The wordtrema(French:tréma), used in linguistics and alsoclassical scholarship,describes the form of both the umlaut diacritic and the diaeresis rather than their function and is used in those contexts to refer to either.

Uses

Diaeresis

Main article:Diaeresis (diacritic)

As the "diaeresis" diacritic, it is used to mark the separation of two distinct vowels in adjacent syllables when an instance ofdiaeresis (or hiatus)occurs, so as to distinguish from adigraphordiphthong.For example, in the obsolete spelling "coöperate", the diaeresis reminded the reader that the word has four syllablesco-op-er-ate,not three. It is used in several languages of western and southern Europe, though rarely now in English.One well-known usage is inFrench- the diaeresis is used in naïve, which is commonly spelled in English without the diaeresis. It is, however, obligatory in French, to show that it is pronounced [na.iv] rather than [nev].

Umlaut

Main article:Umlaut (diacritic)

As the "umlaut" diacritic, it indicates asound shift– also known asumlaut– in which aback vowelbecomes afront vowel.It is a specific feature ofGermanand other Germanic languages, affecting the graphemes⟨a⟩,⟨o⟩,⟨u⟩and⟨au⟩,which are modified to⟨ä⟩,⟨ö⟩,⟨ü⟩and⟨äu⟩.

It derives from theSutterlinscript, formerly used widely in German handwriting, in which the lettereis formed as two short parallel vertical lines very close together (see underSütterlin#Characteristics).

Stylistic use

The two dot diacritic is also sometimes used for purely stylistic reasons. For example, theBrontë family,whose surname was derived fromGaelicand had beenanglicisedas "Prunty", or "Brunty": At some point, the father of the sisters,Patrick Brontë(born Brunty), decided on the alternative spelling with a diaeresis diacritic over the terminal⟨e⟩to indicate that the name had two syllables.

Similarly the "metal umlaut"is a diacritic that is sometimes used gratuitously or decoratively over letters in the names ofhard rockorheavy metalbands – for example, those ofMotörheadandMötley Crüe,and of parody bands, such asSpın̈al Tap.

Other uses by language

A double dot is also used as a diacritic in cases where it functions as neither a diaeresis nor an umlaut. In theInternational Phonetic Alphabet(IPA), a double dot above a letter is used for acentralized vowel,a situation more similar to umlaut than to diaeresis. In other languages it is used for vowel length, nasalization, tone, and various other uses where diaeresis or umlaut was available typographically. The IPA uses a double dot below a letter to indicatebreathy (murmured) voice.

Vowels

• InAlbanian,Tagalog,andKashubian,⟨ë⟩represents aschwa[ə].
• InAymara,a double dot is used on⟨ä⟩⟨ï⟩⟨ü⟩forvowel length.
• In the Basque dialect of Soule,⟨ü⟩represents[y]
• In the DMG romanization ofTunisian Arabic,⟨ä⟩,⟨ö⟩,⟨ṏ⟩,⟨ü⟩,and⟨ṻ⟩represent[æ],[œ],[œ̃],[y],and[y:].
• InLigurianofficial orthography,⟨ö⟩is used to represent the sound[oː].
• InMāori,a diaeresis (e.g.wähine) was often used on computers in the past instead of themacronto indicate long vowels, as the diaeresis was relatively easy to produce on many systems, and the macron difficult or impossible.
• InSeneca,⟨ë⟩⟨ö⟩arenasal vowels,though⟨ä⟩is[ɛ],as in German umlaut.
• InVurës(Vanuatu),⟨ë⟩and⟨ö⟩encode respectively[œ]and[ø].
• In thePahawh Hmongscript, a double dot is used as one of several tone marks.
• The double dot was used in theearly Cyrillic Alpha bet,which was used to writeOld Church Slavonic.The modernCyrillicBelarusianandRussianAlpha bets include the letter⟨ё⟩(yo), although replacing it with the letter⟨е⟩without the diacritic is allowed in Russian.
• Since the 1870s,⟨Ї⟩,⟨ї⟩(Cyrillic letteryi) has been used in theUkrainian Alpha betforiotated[ji];plainіis not iotated[i].InUdmurt,ӥis used for uniotated[i],withиfor iotated[ji].
• The form⟨ÿ⟩is common inDutchhandwriting and also occasionally used in printed text – but is a form ofthe digraph "ij"rather than a modification of the letter⟨y⟩.
• KomiandUdmurtuse⟨Ӧ⟩(a Cyrillic O with two dots) for[ə].
• TheSwedish,FinnishandEstonianlanguages use⟨Ä⟩and⟨Ö⟩to represent[æ]and[ø]
• In the languages ofJ.R.R. Tolkien'sMiddle-Earthnovels, a diaeresis is used to separate vowels belonging to different syllables (e.g. inEärendil) and on final e to mark it asnotaschwa(e.g. inManwë,Aulë,Oromë,etc.). (There is no schwa in these languages but Tolkien wanted to make sure that readers wouldn't mistakenly pronounce one when speaking the names aloud.)

Consonants

Jacaltec(aMayanlanguage) andMalagasyare among the very few languages with a double dot on the letter "n"; in both,n̈is thevelar nasal[ŋ].

InUdmurt,a double dot is also used with the consonant lettersӝ[dʒ](from ж[ʒ]),ӟ[dʑ](from з[z]~[ʑ]) andӵ[tʃ](from ч[tɕ]).

When distinction is important,Ḧandẍare used for representing[ħ]and[ɣ]in the KurdishKurmanji Alpha bet(which are otherwise represented by "h" and "x" ). These sounds are borrowed from Arabic.

Ẅandÿ:Ÿis generally a vowel, but it is used as the (semi-vowel) consonant[ɰ](a[w]without the use of the lips) inTlingit.This sound is also found inCoast Tsimshian,where it is writtenẅ.

A number of languages inVanuatuuse double dots on consonants, to representlinguolabial(or "apicolabial" ) phonemes in their orthography. ThusArakicontrasts bilabialp[p]with linguolabialp̈[t̼];bilabialm[m]with linguolabialm̈[n̼];and bilabialv[β]with linguolabialv̈[ð̼].

Senecauses⟨s̈⟩for[ʃ].

InArabicthe letterẗis used in theISO 233transliteration for thetāʾ marbūṭah[ة], used to mark feminine gender in nouns and adjectives.

Syriacuses a two dots above a letter, calledSiyame,to indicate that the word should be understood as plural. For instance,ܒܝܬܐ(bayta) means "house", whileܒܝ̈ܬܐ(bayte) means "houses". The sign is used especially when no vowel marks are present, which could differentiate between the two forms. Although the origin of theSiyameis different from that of the diaeresis sign, in modern computer systems both are represented by the same Unicode character. This, however, often leads to wrong rendering of the Syriac text.

TheN'Ko script,used to write theMandé languagesofWest Africauses a two-dot diacritic (among others) to represent non-native sounds. The dots are slightly larger than those used for diaeresis or umlaut.

Diacritic underneath

See also:Romanization

The IPA specifies a "subscript umlaut", for example Hindi[kʊm̤ar]"potter";theALA-LC romanizationsystem provides for its use and is one of themain schemes to romanize Persian(for example, rendering⟨ض⟩as⟨z̤⟩). The notation was used to write some Asian languages in Latin script, for exampleRed Karen.

Side dots

The diacritics〮and〯,known as Bangjeom (방점; bàng điểm), were used to mark pitch accents inHangulforMiddle Korean.They were written to the left of a syllable in vertical writing and above a syllable in horizontal writing.

Computer encodings

In Unicode

Character encodinggenerally treats the umlaut and the diaeresis as the same diacritic mark.Unicoderefers to both as diaereses without making any distinction, although the term itselfhas a more precise literary meaning.For example,U+00F6öLATIN SMALL LETTER O WITH DIAERESISrepresents botho-umlautando-diaeresis,while similar codes are used to represent all such cases.

Unicode encodes a number of cases of "letter with a two dots diacritic" asprecomposed charactersand these are displayed below. (Unicode uses the term "Diaeresis" for all two-dot diacritics, irrespective of the actual term used for the language in question.) In addition, many more symbols may be composed using thecombining characterfacility,U+0308◌̈COMBINING DIAERESIS,that may be used with any letter or other diacritic to create a customised symbol but this does not mean that the result has any real-world application and are not shown in the table.

• Diaeresis◌̈ ◌̤
  Latin:Ä ä
• Ǟ ǟ
• C̈ c̈
• Ë ë
• Ï ï
• Ḯ ḯ
• J̈ j̈
• K̈ k̈
• L̈ l̈
• M̈ m̈
• N̈ n̈
• Ö ö
• Ȫ ȫ
• Ǫ̈ ǫ̈
• Ṏ ṏ
• S̈ s̈
• T̈ ẗ
• Ü ü
• Ǖ ǖ
• Ǘ ǘ
• Ǚ ǚ
• Ǜ ǜ
• Ṳ ṳ
• Ṻ ṻ
• ᴞ
  Greek:Ϊ ϊ
• Ϋ ϋ
• ῢ ΰ ῧ
• ϔ
  Cyrillic:Ӓ ӓ
• Ё ё
• Ӛ ӛ
• Ӝ ӝ
• Ӟ ӟ
• Ӥ ӥ
• Ї ї
• Ӧ ӧ
• Ӫ ӫ
• Ӱ ӱ
• Ӵ ӵ
• Ӹ ӹ
• Ӭ ӭ

Both the combining characterU+0308and the pre-composed codepoints may be regarded as an umlaut or a diaeresis according to context. Compound diacritics are possible, for exampleU+01DAǚLATIN SMALL LETTER U WITH DIAERESIS AND CARON,used as atonal marks for Hanyu Pinyin,which uses both a two dots diacritic with acarondiacritic. Conversely, when the letter to be accented is an⟨i⟩,the diacritic replaces thetittle,thus:⟨ï⟩.

Sometimes, there's a need to distinguish between the umlaut sign and the diaeresis sign. For instance, either mayappear in a German name.ISO/IEC JTC 1/SC 2/WG 2 recommends the following for these cases:

• To represent theumlautuse the Combining Diaeresis (U+0308)
• To represent thediaeresisuseCombining Grapheme Joiner(CGJ, U+034F) + Combining Diaeresis (U+0308)

The same advice can be found in the official Unicode FAQ.

Since version 3.2.0, Unicode also providesU+0364◌ͤCOMBINING LATIN SMALL LETTER Ewhich can produce the older umlaut typography.

Unicode provides a combining double dot below asU+0324◌̤COMBINING DIAERESIS BELOW.

Finally, for use with theN'Ko script,there isU+07F3◌߳NKO COMBINING DOUBLE DOT ABOVE.

In ASCII, ISO/IEC 646 and ISO 8859

For broader coverage of this topic, seeWestern Latin character sets (computing).

ASCII,a seven-bit code with just 95 "printable" characters, has no provision for any kind of dot diacritic. Subsequent standardisation treated ASCII as the US national variant ofISO/IEC 646:the French, German and other national variantsreassigned a few code pointsto specific vowels with diacritics, as precomposed characters.

The subsequent (eight bit)ISO 8859-1character encoding includes the lettersä,ë,ï,ö,ü,and their respectivecapitalforms, as well asÿinlower caseonly, withŸadded in the revised editionISO 8859-15andWindows-1252.

These standards are technically obsolete, having been replaced by Unicode.

Computer usage

Character encodinggenerally treats the umlaut and the diaeresis as the same diacritic mark.Unicoderefers to both as diaereses without making any distinction, although the term itselfhas a more precise literary meaning.For example,U+00F6öLATIN SMALL LETTER O WITH DIAERESISrepresents botho-umlautando-diaeresis,while similar codes are used to represent all such cases.

Keyboard input

Letters with umlaut on aGerman computer keyboard.

In countries where the local language(s) routinely include letters with a circumflex, local keyboards are typically engraved with those symbols. If letters with double dots are not present on the keyboard, there are a number of ways to input them into a computer system.

Apple MacOS, iOS

iOS provides accented letters through press-and-hold on most European Latin-script keyboards, including English. Some keyboard layouts feature combining-accent keys that can add accents to any appropriate letter. A letter with double dots can be produced by pressing⌥ Option+U,then the letter. This works on English and other keyboards and is documented further in the supplied manuals.

Google ChromeOS

ForChromeOSwithUS-Internationalkeyboard setting, the combination is"+(letter).For ChromeOS withUK extendedsetting, useAltGr⇧ Shift2,release, then the letter.Alternatively, the Unicode codepoint may be entered directly, usingCtrl+⇧ Shift+u,release, then the four-digit code, then↵ EnterorSpace.

Microsoft Windows

AZERTYandQZERTYkeyboards (as used in much of Europe) includeprecomposed characters(accented letters) as standard and these are fully supported byMicrosoft Windows,typically accessed using theAltGrkey.

For users with aUS keyboard layout,Windows includes a setting"US International",which supports creation of accented letters by changing the function of some keys intodead keys.If the user enters ", nothing will appear on screen, until the user types another character, after which the characters will be merged if possible, or added independently at once if not. Alternatively, the desired character may be generated usingAlt codes.

For users in the United Kingdom and Ireland withQWERTYkeyboards, Windows has an "Extended"setting such that an accented letter can be created usingAltGr2then the base letter.

When usingMicrosoft Wordfor Windows orOutlook,a letter with double dots can be produced by pressingCtrl⇧ Shift:and then the letter.

Linux / X Window System

X-based systems,Composea"produces ä, and similarly for many other letters including capital letters.

In addition any Unicode code point can be entered, for instanceCtrl+⇧ Shift+UF6Spaceproduces U+00F6 which is ö.

Dedicated keys

The German keyboard has dedicated keys forü ö ä.Scandinavian and Turkish keyboards have dedicated keys for their respective language-specific letters, includingöfor Swedish, Finnish, and Icelandic, and bothöandüfor Turkish. French and BelgianAZERTYkeyboards have adead keywhich adds a circumflex (if without Shift) or a diaeresis/umlaut (if with Shift) to the letter key immediately following (for instance Shift-^ followed by e gives ë).

Other scripts

For non-Latin scripts, Greek and Russian use press-and-hold for double-dot diacritics on only a few characters. The Greek keyboard has dialytica and dialytica–tonos variants for upsilon and iota (ϋ ΰ ϊ ΐ), but not for ε ο α η ω, following modern monotonic usage. Russian keyboards feature separate keys for е and ё.

On-screen keyboards

The early 21st century has seen noticeable growth in stylus- and touch-operated interfaces, making the use of on-screen keyboards operated by pointing devices (mouse, stylus, or finger) more important. These "soft" keyboards may replicate the modifier keys found on hardware keyboards, but they may also employ other means of selecting options from a base key, such as right-click or press-and-hold. Soft keyboards may also have multiple contexts, such as letter, numeric, and symbol.

HTML

InHTML,vowels with double dots can be entered with an entity reference of the form&?uml;,where?can be any ofa,e,i,o,u,yor theirmajusculecounterparts. For instanceÄproduces Ä.

TeX and LaTeX

TeX(and its derivatives, most notablyLaTeX) also allows double dots to be placed over letters. The standard way is to use the control sequence\ "followed by the relevant letter, e.g.\ "u.It is good practice to set the sequence off with curly braces:{\ "u}or\ "{u}.

TeX's "German" package can be used: it adds the"control sequence (without the backslash) to produce the Umlaut. However, this can cause conflicts if the main language of the document is not German. Since the integration of Unicode through the development ofXeTeXandXeLaTeX,it is also possible to input the Unicode character directly into the document, using one of the recognized methods such asCompose keyor directUnicode input.

TeX's traditional control sequences can still be used and will produce the same output (in very early versions ofTeXthese sequences would produce double dots that were too far above the letter's body).

All these methods can be used with all available font variations (underlined, strikethrough etc.).

See also

• Dot (diacritic)
• Two dots (disambiguation)