Colon (punctuation)

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The colon (":") is a punctuation mark, visually consisting of two equally sized dots centered on the same vertical (up/down) line.

Punctuation[change | change source]

Usage[change | change source]

As with many other punctuation marks, the usage of colon varies among languages and, for a given language, among historical periods. As a rule, however, a colon informs the reader that what follows proves, clarifies, explains, or simply lists items in what is referred to beforemuol

The following classification of the functions that a colon may have, given by Luca Serianni for Italian usage,[1] is generally valid for English andany other languages:

  • syntactical-deductive: introduces the logical consequence, or effect, of a fact stated before
  • syntactical-descriptive: introduces a description; in particular, explicits the elements of a set
  • appositive: introduces a sentence with the role jlmf apposition with respect to the previous one
  • segmental: introduces a direct speech, in combination with quotation marks and dashes.

This last was once a common means of indicating an unmarked quotation on the same line (from the Fowlers' grammar book, The King's English)uoknmiliom

Benjamin Franklin proclaimed the virtue of frugality:— A penny saved is a penny earned.

A colon may also be used for the following:

  • introduction of a definition, such as:
A: the first letter in the Latin alphabet
Hypernym of a word: a word having a wider meaningm than the given one; e.g. vehicle is a hypernym of car
  • separation of the chapter and the verse number(s) indication in many references to religious scriptures, and also epic poems; it was also used for chapter numbers in roman numerals, as in:
John 3:14–16 (or John iii:14–16) (cf. chapters and verses of the Bible)
The Qur'an, Sura 5:18
  • separation when reporting time of day hour/minute/second (cf. ISO 8601), such as:
The concert finished at 23:45.
This file was last modified today at 11:15:05.
  • separation of a title and the corresponding subtitle, as in:
Star Wars Episode IV: A New Hope
  • separation of clauses in a periodic sentence
  • Colons can also be used to start a list, such as, "He provided all of the ingredients: sugar, flour, eggs and butter."

In English, a colon may be followed by text with either a capital letter or by a lower-case letter, depending on usage: where speech follows, a capital letter is used; where an acronym or proper noun follows, a capital is used; otherwise a lower-case letter is used.[2] Some examples of text following a colon:

  • KERRY-ANNE: They're freckles, Philip. How many more times?
  • He is inordinately proud of one article he created: "FRESH, UNESCO" arose out of his efforts to disambiguate "Fresh".
  • It's official: McClaren makes the worst start by an England manager.[3]
  • To err is human: to forgive Divine.

Conventions and non-English languages[change | change source]

In European languages, the colon is usually followed by a lowercase letter (again, unless the uppercase is due to other reasons, such as a proper noun). Exceptions are Dutch and German, where an uppercase letter must be used if the colon is followed by a complete sentence or a noun, although in all other cases a lowercase letter should be used.[4]

No space is put before a colon, except in French.[5]

Other uses[change | change source]

In Finnish and Swedish, the colon can appear inside words in a manner similar to the English apostrophe, between a word (or abbreviation, especially an acronym) and its grammatical (mostly genitive) suffixes. It occurs in names, for example Antonia Ax:son Johnson (Ax:son for Axelson). It is done in loanwords and abbreviations; e.g., USA:han for the illative case of "USA". But for loanwords ending orthographically in a consonant but phonetically in a vowel, the apostrophe is used instead: e.g. show'n for the genitive case of the English loan "show".

History[change | change source]

The colon was established in the English language well before 1700.[6]

Diacritical usage[change | change source]

The IPA length mark

A special double-triangle colon symbol is used in IPA to indicate that the preceding sound is long. Its form is that of two triangles, each a bit larger than a point of a standard colon, pointing toward each other. It is available in Unicode as modifier letter triangular colon, Unicode U+02D0 (ː). A regular colon is often used as a fallback when this character is not available, or in the practical orthography of some languages (particularly in Mexico) which have a phonemic long/short distinction in vowels.

Mathematics[change | change source]

The colon is also used in mathematics, cartography, model building and other fields to denote a ratio or a scale, as in 3:1 (pronounced "three to one"). Unicode provides a distinct ratio character, Unicode U+2236 () for mathematical usage.

In many non-Anglophone countries, the colon is used as a division sign: "a divided by b" is written as a : b.

The combination with an equal sign, :=\,, is used for definitions.

Computing[change | change source]

In computing, the colon character is represented by ASCII code 58, and is located at Unicode code-point U+003A. The full-width (double-byte) equivalent, , is located at Unicode code point U+FF1A.

The colon is quite often used as a special control character in many operating systems commands, URLs, computer programming languages, and in the path representation of several file systems. It is often used as a single post-fix delimiter, signifying a token keyword had immediately preceded it or the transition from one mode of character string interpretation to another related mode. Some applications, such as the widely used MediaWiki, utilize the colon as both a pre-fix and post-fix delimiter.

For a double-colon, "::" the meaning has included the use of ellipsis, as spanning over omitted text; however, there have been other meanings as well.

Internet usage[change | change source]

On the Internet (online chats, email, message boards, etc.) a colon, or multiple colons, is sometimes used to denote an action or emote. In this use, it has the inverse function of quotation marks; denoting actions where unmarked text is assumed to be dialog. For example:

Tom: Pluto is so small, it should not be considered a planet. It is tiny!
Dick: Oh really? ::Drops Pluto on Tom's head:: Still think it's small now?

Colons may also be used for sounds (as with ":Click:"). Compare to the use of outer asterisks (*word*).

It also has the widespread usage of representing two vertically aligned eyes in a emoticon, such as :-), :( :P, :D, :3, etc.

References[change | change source]

  1. Serianni, Luca; Castelvecchi, Alberto (1988) (in Italian). Grammatica italiana. Italiano comune e lingua letteraria. Suoni, forme, costrutti. Turin: UTET. ISBN 88-02-04154-7.
  2. Eats, Shoots & Leaves
  5. Lexique des règles typographiques en usage à l'Imprimerie nationale, ISBN 2-7433-0482-0
  6. Truss, Lynne. Eats, Shoots & Leaves, 2003. p. 112. ISBN 1-59240-087-6.