Colon (punctuation)
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The colon (":") is a punctuation mark, visually consisting of two equally sized dots centered on the same vertical line.
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[edit] Punctuation
[edit] Usage
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 enumerates elements of what is referred to before.
The following classification of the functions that a colon may have, given by Luca Serianni for Italian usage,[1] is generally valid for English and many 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 of 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)
- 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
- A: the first letter in the Latin alphabet
- Hypernym of a word: a word having a wider meaning 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
- 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 the day (cf. ISO 8601)
- The concert finished at 23:45
- This file was last modified today at 11:15:05
- separation of a title and the corresponding subtitle
- separation of clauses in a periodic sentence
- Colons can also be used to designate a list, such as, "He provided all of the ingredients: sugar, flour, eggs and butter."
In English, a colon may be followed either by a capital letter or by a lower case letter, as the author prefers (unless a capital letter is necessary for a proper noun).[citation needed] No particular consistency is required within a given text, although it is assumed that use of both capital letters and lower case letters after colons, in a single given text, would serve some purpose in communicating the author's desired meaning, rather than simply reflecting carelessness.
- In British English it is usual practice to follow a colon with a single space and a lower case letter. Proper nouns or acronyms generally keep a capital after a colon.
- To err is human: to forgive Divine
- It's official: McClaren makes the worst start by an England manager.[2]
[edit] Conventions and non-English languages
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.[3]
No space is put before a colon, except in French.[4]
[edit] Other uses
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. This 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".
[edit] History
The colon was established in the English language well before 1700.[5]
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[edit] Diacritical usage
A special triangular 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, and in the practical orthography of some languages (particularly in Mexico) which have a phonemic long/short distinction in vowels.
[edit] Mathematics
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 logic and, correspondingly, when describing the characterizing property of a set, it is used as an alternative to a vertical bar, to mean "such that". Example:
S is the set of (all and only) x in 
such that x is greater than 1 and smaller than 3
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.
[edit] Computing
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 see Paamayim Nekudotayim.
[edit] Internet usage
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. :Click: Compare to the use of the asterisk.
It also has the widespread usage of representing two vertically aligned eyes in a emoticon, such as :), :( :P, :D, etc.
[edit] References
- ^ Serianni, Luca; Castelvecchi, Alberto (1988). Grammatica italiana. Italiano comune e lingua letteraria. Suoni, forme, costrutti (in Italian). Turin: UTET. ISBN 88-02-04154-7.
- ^ http://sport.independent.co.uk/football/comment/article2393323.ece
- ^ http://taaladvies.net/taal/advies/vraag/392/
- ^ Lexique des règles typographiques en usage à l'Imprimerie nationale, ISBN 2-7433-0482-0
- ^ Truss, Lynne. Eats, Shoots & Leaves, 2003. p. 112. ISBN 1-592-40087-6.
