◌̈ ◌̤
Two dots

Diacritical marks of two dots ¨, placed side-by-side over or under a letter, are used in several languages for several different purposes. The most familiar to English-language speakers are the diaeresis and the umlaut, though there are numerous others. For example, in Albanian, ë represents a schwa. Such diacritics are also sometimes used for stylistic reasons (as in the family name Brontë or the band name Mötley Crüe).

In modern computer systems using Unicode, the two-dot diacritics are almost always encoded identically, having the same code point.[1] For example, U+00F6 ö LATIN SMALL LETTER O WITH DIAERESIS represents both o-umlaut and o-diaeresis. Their appearance in print or on screen may vary between typefaces but rarely within the same typeface.

The word trema (French: tréma), used in linguistics and also classical 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.



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 of diaeresis (or hiatus) occurs, so as to distinguish from a digraph or diphthong. For example, in the obsolete spelling "coöperate", the diaeresis reminded the reader that the word has four syllables co-op-er-ate, not three. It is used in several languages of western and southern Europe, though rarely now in English.[2] One well-known usage is in French - 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].


Main article: Umlaut (diacritic)

As the "umlaut" diacritic, it indicates a sound shift  – also known as umlaut – in which a back vowel becomes a front vowel. It is a specific feature of German and other Germanic languages, affecting the graphemes ⟨a⟩, ⟨o⟩, ⟨u⟩ and ⟨au⟩, which are modified to ä, ö, ü and ⟨äu⟩.

It derives from the Sutterlin script, formerly used widely in German handwriting, in which the letter e is formed as two short parallel vertical lines very close together (see under Sütterlin#Characteristics).

Stylistic use

The two dot diacritic is also sometimes used for purely stylistic reasons. For example, the Brontë family, whose surname was derived from Gaelic and had been anglicised as "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 of hard rock or heavy metal bands – for example, those of Motörhead and Mötley Crüe, and of parody bands, such as Spın̈al 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 the International Phonetic Alphabet (IPA), a double dot above a letter is used for a centralized 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 indicate breathy (murmured) voice.[3][b]



Jacaltec (a Mayan language) and Malagasy are among the very few languages with a double dot on the letter "n"; in both, is the velar nasal [ŋ].

In Udmurt, a double dot is also used with the consonant letters ӝ [dʒ] (from ж [ʒ]), ӟ [dʑ] (from з [z] ~ [ʑ]) and ӵ [tʃ] (from ч [tɕ]).

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

and ÿ: Ÿ is generally a vowel, but it is used as the (semi-vowel) consonant [ɰ] (a [w] without the use of the lips) in Tlingit. This sound is also found in Coast Tsimshian, where it is written .

A number of languages in Vanuatu use double dots on consonants, to represent linguolabial (or "apicolabial") phonemes in their orthography. Thus Araki contrasts bilabial p [p] with linguolabial [t̼]; bilabial m [m] with linguolabial [n̼]; and bilabial v [β] with linguolabial [ð̼].

Seneca uses ⟨s̈⟩ for [ʃ].

In Arabic the letter is used in the ISO 233 transliteration for the tāʾ marbūṭah [ة], used to mark feminine gender in nouns and adjectives.

Syriac uses a two dots above a letter, called Siyame, to indicate that the word should be understood as plural. For instance, ܒܝܬܐ (bayta) means "house", while ܒܝ̈ܬܐ (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 the Siyame is 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.

The N'Ko script, used to write the Mandé languages of West Africa uses 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";[3]: 25  the ALA-LC romanization system provides for its use and is one of the main schemes to romanize Persian (for example, rendering ض as ⟨z̤⟩). The notation was used to write some Asian languages in Latin script, for example Red Karen.

Computer encodings

In Unicode

Character encoding generally treats the umlaut and the diaeresis as the same diacritic mark. Unicode refers to both as diaereses without making any distinction, although the term itself has a more precise literary meaning. For example, U+00F6 ö LATIN SMALL LETTER O WITH DIAERESIS represents both o-umlaut and o-diaeresis, while similar codes are used to represent all such cases.

Unicode encodes a number of cases of "letter with a two dots diacritic" as precomposed characters and 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 the combining character facility, 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.

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

Sometimes, there's a need to distinguish between the umlaut sign and the diaeresis sign. For instance, either may appear in a German name. ISO/IEC JTC 1/SC 2/WG 2 recommends the following for these cases:[6]

The same advice can be found in the official Unicode FAQ.[7]

Since version 3.2.0, Unicode also provides U+0364 ◌ͤ COMBINING LATIN SMALL LETTER E which can produce the older umlaut typography.

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

Finally, for use with the N'Ko script, there is U+07F3 ◌߳ NKO COMBINING DOUBLE DOT ABOVE.

In ASCII, ISO/IEC 646 and ISO 8859

For broader coverage of this topic, see Western 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 of ISO/IEC 646: the French, German and other national variants reassigned a few code points to specific vowels with diacritics, as precomposed characters.

The subsequent (eight bit) ISO 8859-1 character encoding includes the letters ä, ë, ï, ö, ü, and their respective capital forms, as well as ÿ in lower case only, with Ÿ added in the revised edition ISO 8859-15 and Windows-1252.

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

Computer usage

Character encoding generally treats the umlaut and the diaeresis as the same diacritic mark. Unicode refers to both as diaereses without making any distinction, although the term itself has a more precise literary meaning. For example, U+00F6 ö LATIN SMALL LETTER O WITH DIAERESIS represents both o-umlaut and o-diaeresis, while similar codes are used to represent all such cases.

Keyboard input

Letters with umlaut on a German 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.[8]

Google ChromeOS

For ChromeOS with US-International keyboard setting, the combination is "+(letter).[9] For ChromeOS with UK extended setting, use AltGr⇧ Shift2, release, then the letter.[citation needed] Alternatively, the Unicode codepoint may be entered directly, using Ctrl+⇧ Shift+u, release, then the four-digit code, then ↵ Enter or Space.[10]

Microsoft Windows

AZERTY and QZERTY keyboards (as used in much of Europe) include precomposed characters (accented letters) as standard and these are fully supported by Microsoft Windows, typically accessed using the AltGr key.

For users with a US keyboard layout, Windows includes a setting "US International", which supports creation of accented letters by changing the function of some keys into dead 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 using Alt codes.

For users in the United Kingdom and Ireland with QWERTY keyboards, Windows has an "Extended" setting such that an accented letter can be created using AltGr2 then the base letter.

When using Microsoft Word for Windows or Outlook, a letter with double dots can be produced by pressing Ctrl⇧ 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 instance Ctrl+⇧ Shift+UF6Space produces U+00F6 which is ö.

Dedicated keys

The German keyboard has dedicated keys for ü ö ä. Scandinavian and Turkish keyboards have dedicated keys for their respective language-specific letters, including ö for Swedish, Finnish, and Icelandic, and both ö and ü for Turkish. French and Belgian AZERTY keyboards have a dead key which 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.


In HTML, vowels with double dots can be entered with an entity reference of the form &?uml;, where ? can be any of a, e, i, o, u, y or their majuscule counterparts. For instance Ä produces Ä.

TeX and LaTeX

TeX (and its derivatives, most notably LaTeX) 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 of XeTeX and XeLaTeX, it is also possible to input the Unicode character directly into the document, using one of the recognized methods such as Compose key or direct Unicode input.

TeX's traditional control sequences can still be used and will produce the same output (in very early versions of TeX these 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


  1. ^ The diacritic is referred to in Unicode as a diaeresis, without distinction, although the term has a more precise literary meaning.
  2. ^ The IPA Handbook calls the mark "subscript umlaut", in contrast with the Unicode Consortium's choice of "diaeresis below".


  1. ^ The Unicode Standard v 5.0. San Francisco: Addison-Wesley. 2006. p. 228. ISBN 0-321-48091-0.
  2. ^ Baum, Dan (16 December 2010). "The New Yorker's odd mark — the diaeresis". Dscriber. Trade Secrets. Archived from the original on 16 December 2010. Among the many mysteries of The New Yorker is that funny little umlaut over words like coöperate and reëlect. The New Yorker seems to be the only publication on the planet that uses it, and I always found it a little pretentious until I did some research. Turns out, it's not an umlaut. It's a diaeresis.
  3. ^ a b International Phonetic Association (2021). Handbook of the International Phonetic Association : a guide to the use of the International Phonetic Alphabet. Cambridge: Cambridge University Press. ISBN 9780521652360..
  4. ^ "Māori Orthographic Conventions". Māori Language Commission. Archived from the original on 2009-09-06. Retrieved 11 June 2010.
  5. ^ "Māori language on the internet". Te Ara: The Encyclopedia of New Zealand.
  6. ^ Kaplan, Michael S (4 September 2006). "Every character has a story #24: U+0308 (COMBINING DIAERESIS)".
  7. ^ "Characters and Combining Marks | Q: Unicode doesn't seem to distinguish between tréma and umlaut, but I need to distinguish. What shall I do?". Unicode Consortium.
  8. ^ "Enter characters with accent marks on Mac". apple.com. Retrieved 2021-08-07.
  9. ^ Randall, Angela (February 18, 2014). "How to Write Foreign Character Accents Using Your Chromebook". Retrieved March 2, 2020.
  10. ^ Busch, Jack (April 20, 2018). "Type Special Characters with a Chromebook (Accents, Symbols, Em Dashes)". groovypost.com. Retrieved February 28, 2020.