The question mark (also known as interrogation point, query, or eroteme in

journalism Journalism is the production and distribution of reports on the interaction of events, facts, ideas, and people that are the " news of the day" and that informs society to at least some degree. The word, a noun, applies to the occupation (pro ...

) is a

punctuation mark Punctuation (or sometimes interpunction) is the use of spacing, conventional signs (called punctuation marks), and certain typographical devices as aids to the understanding and correct reading of written text, whether read silently or aloud. A ...

that indicates an

interrogative clause An interrogative clause is a clause whose form is typically associated with question-like meanings. For instance, the English sentence "Is Hannah sick?" has interrogative syntax which distinguishes it from its declarative counterpart "Hannah is ...

or phrase in many

language Language is a structured system of communication. The structure of a language is its grammar and the free components are its vocabulary. Languages are the primary means by which humans communicate, and may be conveyed through a variety of ...

History

In the fifth century,

Syriac Syriac may refer to: *Syriac language, an ancient dialect of Middle Aramaic *Sureth, one of the modern dialects of Syriac spoken in the Nineveh Plains region * Syriac alphabet ** Syriac (Unicode block) ** Syriac Supplement * Neo-Aramaic languages a ...

Bible manuscripts used question markers, according to a 2011 theory by manuscript specialist Chip Coakley: he believes the ''zagwa elaya'' ("upper pair"), a vertical double dot over a word at the start of a sentence, indicates that the sentence is a question. Btv1b6000718s

From around 783, in ''

Godescalc Evangelistary The Godescalc Evangelistary, Godescalc Sacramentary, Godescalc Gospels, or Godescalc Gospel Lectionary (Paris, BNF. acquisitions nouvelles lat.1203) is an illuminated manuscript in Latin made by the Frankish scribe Godescalc and today kept in th ...

'', a mark described as "a lightning flash, striking from right to left" is attested. This mark is later called a . According to some paleographers, it may have indicated intonation, perhaps associated with early musical notation like

neume A neume (; sometimes spelled neum) is the basic element of Western and Eastern systems of musical notation prior to the invention of five-line staff notation. The earliest neumes were inflective marks that indicated the general shape but not nec ...

s. Another theory, is that the "lightning flash" was originally a

tilde The tilde () or , is a grapheme with several uses. The name of the character came into English from Spanish, which in turn came from the Latin '' titulus'', meaning "title" or "superscription". Its primary use is as a diacritic (accent) i ...

titlo Titlo is an extended diacritic symbol initially used in early Cyrillic and Glagolitic manuscripts, e.g., in Old Church Slavonic and Old East Slavic languages. The word is a borrowing from the Greek "", "title" (compare dated English '' tittle' ...

, as in , one of many wavy or more or less slanted marks used in

medieval In the history of Europe, the Middle Ages or medieval period lasted approximately from the late 5th to the late 15th centuries, similar to the post-classical period of global history. It began with the fall of the Western Roman Empire ...

texts for denoting things such as

abbreviations An abbreviation (from Latin ''brevis'', meaning ''short'') is a shortened form of a word or phrase, by any method. It may consist of a group of letters or words taken from the full version of the word or phrase; for example, the word ''abbrevia ...

, which would later become various

diacritics A diacritic (also diacritical mark, diacritical point, diacritical sign, or accent) is a glyph added to a letter or to a basic glyph. The term derives from the Ancient Greek (, "distinguishing"), from (, "to distinguish"). The word ''diacriti ...

or ligatures. From the 10th century, the pitch-defining element (if it ever existed) seems to have been gradually forgotten, so that the "lightning flash" sign (with the stroke sometimes slightly curved) is often seen indifferently at the end of clauses, whether they embody a question or not. In the early 13th century, when the growth of communities of scholars (

universities A university () is an institution of higher (or tertiary) education and research which awards academic degrees in several academic disciplines. Universities typically offer both undergraduate and postgraduate programs. In the United States, ...

) in Paris and other major cities led to an expansion and streamlining of the book-production trade, punctuation was rationalized by assigning the "lightning flash" specifically to interrogatives; by this time the stroke was more sharply curved and can easily be recognized as the modern question mark. See for example ' (1496) printed by Aldo Manuzio in

Venice Venice ( ; it, Venezia ; vec, Venesia or ) is a city in northeastern Italy and the capital of the Veneto region. It is built on a group of 118 small islands that are separated by canals and linked by over 400 bridges. The isla ...

. In 1598, the English term ''point of interrogation'' is attested in an

Italian Italian(s) may refer to: * Anything of, from, or related to the people of Italy over the centuries ** Italians, an ethnic group or simply a citizen of the Italian Republic or Italian Kingdom ** Italian language, a Romance language *** Regional Ita ...

–English dictionary by

John Florio Giovanni Florio (1552–1625), known as John Florio, was an English linguist, poet, writer, translator, lexicographer, and royal language tutor at the Court of James I. He is recognised as the most important Renaissance humanist in England. F ...

. In the 1850s, the term ''question mark'' is attested:

The mark which you are to notice in this lesson is of this shape ?You see it is made by placing a little crooked mark over a period. ..The name of this mark is the ''Question Mark'', because it is always put after a question. Sometimes it is called by a longer and harder name. The long and hard name is the ''Interroga'tion Point''.

Scope

In English, the question mark typically occurs at the end of a sentence, where it replaces the full stop (period). However, the question mark may also occur at the end of a clause or phrase, where it replaces the comma : :''Is it good in form? style? meaning?'' or: :"Showing off for him, for all of them, not out of hubris—hubris? him? what did he have to be hubrid about?—but from mood and nervousness." —

Stanley Elkin Stanley Lawrence Elkin (May 11, 1930 – May 31, 1995) was an American novelist, short story writer, and essayist. His extravagant, satirical fiction revolves around American consumerism, popular culture, and male-female relationships. Biograp ...

. This is quite common in

Spanish Spanish might refer to: * Items from or related to Spain: **Spaniards are a nation and ethnic group indigenous to Spain **Spanish language, spoken in Spain and many Latin American countries **Spanish cuisine Other places * Spanish, Ontario, Can ...

, where the use of bracketing question marks explicitly indicates the scope of interrogation. :' ('In case you cannot go with them, would you like to go with us?') A question mark may also appear immediately after questionable data, such as dates: :''Genghis Khan (1162?–1227)''

In other languages and scripts

Opening and closing question marks in Spanish

In Spanish, since the second edition of the ''Ortografía'' of the in 1754, interrogatives require both opening and closing question marks. An interrogative sentence, clause, or phrase begins with an

inverted question mark The inverted question mark, , and inverted exclamation mark, , are punctuation marks used to begin interrogative and exclamatory sentences or clauses in Spanish and some languages which have cultural ties with Spain, such as Asturian and Wara ...

and ends with the question mark , as in: :' – 'She asks me, "What time is it? Question marks must always be matched, but to mark uncertainty rather than actual interrogation omitting the opening one is allowed, although discouraged: :' is preferred in Spanish over ' The omission of the opening mark is common in informal writing, but is considered an error. The one exception is when the question mark is matched with an exclamation mark, as in: :' – 'Who do you think you are?!' (The order may also be reversed, opening with a question mark and closing with an exclamation mark.) Nonetheless, even here the recommends matching punctuation: :' The opening question mark in Unicode is .

In other languages of Spain

Galician also uses the inverted opening question mark, though usually only in long sentences or in cases that would otherwise be ambiguous.

Basque Basque may refer to: * Basques, an ethnic group of Spain and France * Basque language, their language Places * Basque Country (greater region), the homeland of the Basque people with parts in both Spain and France * Basque Country (autonomous co ...

only uses the terminal question mark.

Armenian question mark

Armenian Armenian may refer to: * Something of, from, or related to Armenia, a country in the South Caucasus region of Eurasia * Armenians, the national people of Armenia, or people of Armenian descent ** Armenian Diaspora, Armenian communities across the ...

, the question mark is a

diacritic A diacritic (also diacritical mark, diacritical point, diacritical sign, or accent) is a glyph added to a letter or to a basic glyph. The term derives from the Ancient Greek (, "distinguishing"), from (, "to distinguish"). The word ''diacriti ...

that takes the form of an open circle and is placed over the last vowel of the question word. It is defined in Unicode at .

Greek question mark

The

Greek Greek may refer to: Greece Anything of, from, or related to Greece, a country in Southern Europe: *Greeks, an ethnic group. *Greek language, a branch of the Indo-European language family. **Proto-Greek language, the assumed last common ancestor ...

question mark ( el, ερωτηματικό, links=no, translit=erōtīmatikó) looks like . It appeared around the same time as the Latin one, in the 8th century. It was adopted by Church Slavonic and eventually settled on a form essentially similar to the Latin

semicolon The semicolon or semi-colon is a symbol commonly used as orthographic punctuation. In the English language, a semicolon is most commonly used to link (in a single sentence) two independent clauses that are closely related in thought. When a ...

. In

Unicode Unicode, formally The Unicode Standard,The formal version reference is is an information technology standard for the consistent encoding, representation, and handling of text expressed in most of the world's writing systems. The standard, wh ...

, it is separately encoded as , but the similarity is so great that the

code point In character encoding terminology, a code point, codepoint or code position is a numerical value that maps to a specific character. Code points usually represent a single grapheme—usually a letter, digit, punctuation mark, or whitespace—but ...

is normalised to , making the marks identical in practice. In Greek, the question mark is used even for indirect questions.

Mirrored question mark in right-to-left scripts

Arabic Arabic (, ' ; , ' or ) is a Semitic language spoken primarily across the Arab world.Semitic languages: an international handbook / edited by Stefan Weninger; in collaboration with Geoffrey Khan, Michael P. Streck, Janet C. E.Watson; Walter ...

and other languages that use Arabic script such as

Persian Persian may refer to: * People and things from Iran, historically called ''Persia'' in the English language ** Persians, the majority ethnic group in Iran, not to be conflated with the Iranic peoples ** Persian language, an Iranian language of the ...

Urdu Urdu (;"Urdu"
'' Uyghur (Arabic form), which are written from

right to left In a script (commonly shortened to right to left or abbreviated RTL, RL-TB or R2L), writing starts from the right of the page and continues to the left, proceeding from top to bottom for new lines. Arabic, Hebrew, Persian, Pashto, Urdu, Kashmi ...

, the question mark is mirrored right-to-left from the Latin question mark. In Unicode, two encodings are available: and . (Some browsers may display the character in the previous sentence as a forward question mark due to font or text directionality issues). In addition, the

Thaana Thaana, Taana or Tāna ( ) is the present writing system of the Maldivian language spoken in the Maldives. Thaana has characteristics of both an abugida (diacritic, vowel-killer strokes) and a true alphabet (all vowels are written), ...

script in Dhivehi uses the mirrored question mark: މަރުހަބާ؟ The Arabic question mark is also used in some other right to left scripts:

N'Ko N'Ko () is a script devised by Solomana Kante in 1949, as a modern writing system for the Mandé languages of West Africa. The term ''N'Ko'', which means ''I say'' in all Mandé languages, is also used for the Mandé literary standard written i ...

, and

Hebrew Hebrew (; ; ) is a Northwest Semitic language of the Afroasiatic language family. Historically, it is one of the spoken languages of the Israelites and their longest-surviving descendants, the Jews and Samaritans. It was largely preserved ...

and

Yiddish Yiddish (, or , ''yidish'' or ''idish'', , ; , ''Yidish-Taytsh'', ) is a West Germanic language historically spoken by Ashkenazi Jews. It originated during the 9th century in Central Europe, providing the nascent Ashkenazi community with a ve ...

are also written right-to-left, but they use a question mark that appears on the page in the same orientation as the left-to-right question mark.

Fullwidth question mark in East Asian languages

The question mark is also used in modern writing in

Chinese Chinese can refer to: * Something related to China * Chinese people, people of Chinese nationality, citizenship, and/or ethnicity **''Zhonghua minzu'', the supra-ethnic concept of the Chinese nation ** List of ethnic groups in China, people of ...

and, to a lesser extent,

Japanese Japanese may refer to: * Something from or related to Japan, an island country in East Asia * Japanese language, spoken mainly in Japan * Japanese people, the ethnic group that identifies with Japan through ancestry or culture ** Japanese diaspor ...

. Usually it is written as fullwidth form in Chinese and Japanese, in Unicode: . Chinese and Japanese also have a spoken indicator of questions, 吗 (ma) and か (ka) respectively, which essentially function as a verbal question mark. Because of this, in Japanese use of the question mark is optional with か. Thus the same sentence could be written both いいですか？('May I?') or いいですか。(Still 'May I?'), but usually, the question mark is used.

In other scripts

Some other scripts have a specific question mark: * * * , and *

Stylistic variants

French usage should include a narrow non-breaking space before the question mark. (For example, ""), whereas in the English language orthography no space is allowed in front of the question mark (e.g. "What would you like to drink?").

Typological variants of "?"

The rhetorical question mark or percontation point (see

Irony punctuation Irony punctuation is any form of notation proposed or used to denote irony or sarcasm in text. Written English lacks a standard way to mark irony, and several forms of punctuation have been proposed. Among the oldest and most frequently atte ...

) was invented by

Henry Denham Henry Denham was one of the outstanding England, English Printer (publisher), printers of the sixteenth century. He was apprenticed to Richard Tottel and took up the freedom of the Stationers' Company on 30 August 1560. In 1564 he set up his own ...

in the 1580s and was used at the end of a rhetorical question; however, it became obsolete in the 17th century. It was the reverse of an ordinary question mark, so that instead of the main opening pointing back into the sentence, it opened away from it. This character can be represented using the reversed question mark found at Unicode as U+2E2E. Bracketed question marks can be used for rhetorical questions, for example , in informal contexts such as

closed captioning Closed captioning (CC) and subtitling are both processes of displaying text on a television, video screen, or other visual display to provide additional or interpretive information. Both are typically used as a transcription of the audio po ...

. The question mark can also be used as a meta-sign to signal uncertainty regarding what precedes it. It is usually put between brackets: . The uncertainty may concern either a superficial level (such as unsure spelling), or a deeper

truth Truth is the property of being in accord with fact or reality.Merriam-Webster's Online Dictionarytruth 2005 In everyday language, truth is typically ascribed to things that aim to represent reality or otherwise correspond to it, such as belie ...

(real meaning). In typography, some other variants and combinations are available: "⁇," "⁈," and "⁉," are usually used for chess annotation symbols; the

interrobang The interrobang (), also known as the interabang (often represented by any of ?!, !?, ?!? or !?!), is an unconventional punctuation mark used in various written languages and intended to combine the functions of the question mark, or interro ...

, "‽," is used to combine the functions of the question mark and the

exclamation mark The exclamation mark, , or exclamation point (American English), is a punctuation mark usually used after an interjection or exclamation to indicate strong feelings or to show emphasis. The exclamation mark often marks the end of a sentence, f ...

, superposing these two marks. Unicode makes available these variants: * * * * * * * * *

Computing

computing Computing is any goal-oriented activity requiring, benefiting from, or creating computing machinery. It includes the study and experimentation of algorithmic processes, and development of both hardware and software. Computing has scientific, ...

, the question mark

character Character or Characters may refer to: Arts, entertainment, and media Literature * ''Character'' (novel), a 1936 Dutch novel by Ferdinand Bordewijk * ''Characters'' (Theophrastus), a classical Greek set of character sketches attributed to The ...

is represented by

ASCII ASCII ( ), abbreviated from American Standard Code for Information Interchange, is a character encoding standard for electronic communication. ASCII codes represent text in computers, telecommunications equipment, and other devices. Because ...

code 63 (0x3F hexadecimal), and is located at Unicode code-point . The full-width (double-byte) equivalent (？), is located at code-point . In shell and scripting languages, the question mark is often utilized as a

wildcard character In software, a wildcard character is a kind of placeholder represented by a single character, such as an asterisk (), which can be interpreted as a number of literal characters or an empty string. It is often used in file searches so the full na ...

: a symbol that can be used to substitute for any other character or characters in a string. In particular, filename globbing uses "?" as a substitute for any one character, as opposed to the asterisk, "*", which matches zero or more characters in a string. The

(¿) corresponds to Unicode code-point , and can be accessed from the keyboard in Microsoft Windows on the default US layout by holding down the Alt and typing either 1 6 8 (ANSI) or 0 1 9 1 (Unicode) on the numeric keypad. In GNOME applications on

Linux Linux ( or ) is a family of open-source Unix-like operating systems based on the Linux kernel, an operating system kernel first released on September 17, 1991, by Linus Torvalds. Linux is typically packaged as a Linux distribution, w ...

operating systems, it can be entered by typing the hexadecimal Unicode character (minus leading zeros) while holding down both Ctrl and Shift, I J mm.e.: Ctrl Shift B F. In recent

XFree86 XFree86 is an implementation of the X Window System. It was originally written for Unix-like operating systems on IBM PC compatibles and was available for many other operating systems and platforms. It is free and open source software under the X ...

and X.Org incarnations of the

X Window System The X Window System (X11, or simply X) is a windowing system for bitmap displays, common on Unix-like operating systems. X provides the basic framework for a GUI environment: drawing and moving windows on the display device and interacting wi ...

, it can be accessed as a compose sequence of two straight question marks, i.e. pressing Compose ? ? yields ¿. In classic Mac OS and

Mac OS X macOS (; previously OS X and originally Mac OS X) is a Unix operating system developed and marketed by Apple Inc. since 2001. It is the primary operating system for Apple's Mac computers. Within the market of desktop and la ...

(macOS), the key combination Option Shift ? produces an inverted question mark. The question mark is used in ASCII renderings of the

International Phonetic Alphabet The International Phonetic Alphabet (IPA) is an alphabetic system of phonetic notation based primarily on the Latin script. It was devised by the International Phonetic Association in the late 19th century as a standardized representation ...

, such as

SAMPA __NOTOC__ The Speech Assessment Methods Phonetic Alphabet (SAMPA) is a computer-readable phonetic script using 7-bit printable ASCII characters, based on the International Phonetic Alphabet (IPA). It was originally developed in the late 1980s for ...

, in place of the glottal stop symbol, , (which resembles "?" without the dot), and corresponds to Unicode code point . In

computer programming Computer programming is the process of performing a particular computation (or more generally, accomplishing a specific computing result), usually by designing and building an executable computer program. Programming involves tasks such as anal ...

, the symbol "?" has a special meaning in many

programming language A programming language is a system of notation for writing computer programs. Most programming languages are text-based formal languages, but they may also be graphical. They are a kind of computer language. The description of a programming ...

s. In C-descended languages, ? is part of the ?: operator, which is used to evaluate simple boolean conditions. In C# 2.0, the ? modifier is used to handle nullable data types and ?? is the

null coalescing operator The null coalescing operator (called the Logical Defined-Or operator in Perl) is a binary operator that is part of the syntax for a basic conditional expression in several programming languages, including C#, PowerShell as of version 7.0.0, Perl ...

. In the

POSIX The Portable Operating System Interface (POSIX) is a family of standards specified by the IEEE Computer Society for maintaining compatibility between operating systems. POSIX defines both the system- and user-level application programming inter ...

syntax for

regular expression A regular expression (shortened as regex or regexp; sometimes referred to as rational expression) is a sequence of characters that specifies a search pattern in text. Usually such patterns are used by string-searching algorithms for "find" ...

s, such as that used in

Perl Perl is a family of two high-level, general-purpose, interpreted, dynamic programming languages. "Perl" refers to Perl 5, but from 2000 to 2019 it also referred to its redesigned "sister language", Perl 6, before the latter's name was offic ...

and

Python Python may refer to: Snakes * Pythonidae, a family of nonvenomous snakes found in Africa, Asia, and Australia ** ''Python'' (genus), a genus of Pythonidae found in Africa and Asia * Python (mythology), a mythical serpent Computing * Python (pro ...

, ? stands for "zero or one instance of the previous subexpression", i.e. an optional element. It can also make a quantifier like , + or * match as few characters as possible, making it lazy, e.g. /^.*?px/ will match the substring 165px in 165px 17px instead of matching 165px 17px. In certain implementations of the BASIC programming language, the ? character may be used as a shorthand for the "print" function; in others (notably the

BBC BASIC BBC BASIC is a version of the BASIC programming language released in 1981 as the native programming language for the BBC Micro home/personal computer, providing a standardized language for a UK computer literacy project of the BBC. It was wr ...

family), ? is used to address a single-byte memory location. In OCaml, the question mark precedes the label for an optional parameter. In Scheme, as a convention, symbol names ending in ? are used for predicates, such as odd?, null?, and eq?. Similarly, in

Ruby A ruby is a pinkish red to blood-red colored gemstone, a variety of the mineral corundum ( aluminium oxide). Ruby is one of the most popular traditional jewelry gems and is very durable. Other varieties of gem-quality corundum are called ...

, method names ending in ? are used for predicates. In

Swift Swift or SWIFT most commonly refers to: * SWIFT, an international organization facilitating transactions between banks ** SWIFT code * Swift (programming language) * Swift (bird), a family of birds It may also refer to: Organizations * SWIFT, ...

a type followed by ? denotes an

option type In programming languages (especially functional programming languages) and type theory, an option type or maybe type is a polymorphic type that represents encapsulation of an optional value; e.g., it is used as the return type of functions whic ...

; ? is also used in "optional chaining", where if an option value is nil, it ignores the following operations. Similarly, in Kotlin, a type followed by ? is nullable and functions similar to option chaining are supported. In APL, ? generates random numbers or a random subset of indices. In

Rust Rust is an iron oxide, a usually reddish-brown oxide formed by the reaction of iron and oxygen in the catalytic presence of water or air moisture. Rust consists of hydrous iron(III) oxides (Fe2O3·nH2O) and iron(III) oxide-hydroxide (FeO( ...

, a ? suffix on a function or method call indicates error handling. In

SPARQL SPARQL (pronounced " sparkle" , a recursive acronym for SPARQL Protocol and RDF Query Language) is an RDF query language—that is, a semantic query language for databases—able to retrieve and manipulate data stored in Resource Description ...

, the question mark is used to introduce variable names, such as ?name. In MUMPS, it is the pattern match operator. In many

Web browser A web browser is application software for accessing websites. When a user requests a web page from a particular website, the browser retrieves its files from a web server and then displays the page on the user's screen. Browsers are used o ...

s and other computer programs, when converting text between encodings, it may not be possible to map some characters into the target

character set Character encoding is the process of assigning numbers to graphical characters, especially the written characters of human language, allowing them to be stored, transmitted, and transformed using digital computers. The numerical values tha ...

. In this situation it is common to replace each unmappable character with a question mark ?, inverted question mark ¿, or the Unicode

replacement character Specials is a short Unicode block of characters allocated at the very end of the Basic Multilingual Plane, at U+FFF0–FFFF. Of these 16 code points, five have been assigned since Unicode 3.0: *, marks start of annotated text *, marks start ...

, usually rendered as a white question mark in a black diamond: . This commonly occurs for apostrophes and quotation marks when they are written with software that uses its own proprietary non-standard code for these characters, such as

Microsoft Office Microsoft Office, or simply Office, is the former name of a family of client software, server software, and services developed by Microsoft. It was first announced by Bill Gates on August 1, 1988, at COMDEX in Las Vegas. Initially a marketi ...

's "smart quotes". The generic URL syntax allows for a

query string A query string is a part of a uniform resource locator (URL) that assigns values to specified parameters. A query string commonly includes fields added to a base URL by a Web browser or other client application, for example as part of an HTML, cho ...

to be appended to a resource location in a Web address so that additional information can be passed to a script; the query mark, ?, is used to indicate the start of a query string. A query string is usually made up of a number of different field/value pairs, each separated by the ampersand symbol, &, as seen in this URL: http://www.example.com/search.php?query=testing&database=English Here, a script on the page search.php on the server www.example.com is to provide a response to the query string containing the pairs query=testing and database=English.

Games

algebraic chess notation Algebraic notation (or AN) is the standard method for recording and describing the moves in a game of chess. It is based on a system of coordinates to uniquely identify each square on the chessboard. It is used by most books, magazines, and news ...

, some

chess punctuation When annotating chess games, commentators frequently use widely recognized annotation symbols. Question marks and exclamation points that denote a move as bad or good are ubiquitous in chess literature. Some publications intended for an internati ...

conventions include: "?" denotes a bad move, "??" a blunder, "?!" a

dubious Doubt is a mental state in which the mind remains suspended between two or more contradictory propositions, unable to be certain of any of them. Doubt on an emotional level is indecision between belief and disbelief. It may involve uncertainty ...

move, and "!?" an interesting move. In

Scrabble ''Scrabble'' is a word game in which two to four players score points by placing tiles, each bearing a single letter, onto a game board divided into a 15×15 grid of squares. The tiles must form words that, in crossword fashion, read left t ...

, a question mark indicates a blank tile.

Mathematics and formal logic

In mathematics, "?" commonly denotes

Minkowski's question mark function In mathematics, the Minkowski question-mark function, denoted , is a function with unusual fractal properties, defined by Hermann Minkowski in 1904. It maps quadratic irrational numbers to rational numbers on the unit interval, via an expressio ...

. In equations, it can mean "questioned" as opposed to "defined". * * * In linear logic, the question mark denotes one of the exponential modalities that control weakening and contraction.

Medicine

A question mark is used in English medical notes to suggest a possible

diagnosis Diagnosis is the identification of the nature and cause of a certain phenomenon. Diagnosis is used in many different disciplines, with variations in the use of logic, analytics, and experience, to determine " cause and effect". In systems engin ...

. It facilitates the recording of a doctor's impressions regarding a patient's symptoms and signs. For example, for a patient presenting with left lower abdominal pain, a differential diagnosis might include ''? diverticulitis'' (read as "query diverticulitis").

Notes

References

Bibliography

* *

External links

* – provides an overview of question mark usage, and the differences between direct, indirect, and rhetorical questions. {{DEFAULTSORT:Question Mark Interrogative words and phrases Punctuation Typographical symbols