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The full stop symbol derives from Aristophanes of Byzantium who invented the system of punctuation where the height of placement of a dot on the line determined its meaning. The high dot (˙) was called a "periodos" and indicated a finished thought or sentence, the middle dot (·) was called a "kolon" and indicated part of a complete thought, while the low dot (.) was called a "telia" (from Greek τέλος "telos: end") and also indicated part of a complete thought.
Full stops are one of the most commonly used punctuation marks; analysis of texts indicate that approximately half of all punctuation marks used are full stops.
Full stops are used to indicate the end of sentences.
A full stop is used after some abbreviations. If the abbreviation ends a declaratory sentence there is no additional period immediately following the full stop that ends the abbreviation (e.g., My name is Gabriel Gama, Jr.). This is called haplography. Though two full stops (one for the abbreviation, one for the sentence ending) might be expected, conventionally only one is written. In the case of an interrogative or exclamatory sentence ending with an abbreviation, a question or exclamation mark can still be added (e.g., Are you Gabriel Gama, Jr.?).
Abbreviations & Personal Titles of Address
According to the Oxford A–Z of Grammar and Punctuation, "If the abbreviation includes both the first and last letter of the abbreviated word, as in 'Mister' ["Mr"] and 'Doctor' ["Dr"], a full stop is not used." This does not include, for example, the standard abbreviations for titles such as Professor ("Prof.") or Reverend ("Rev."), because they do not end with the last letter of the word they are abbreviating.
Among American dialects, however, the above convention is not well known and often not adhered to.
In this use, the full stop is also occasionally known as a suspension mark. This originates from the old practice of marking the end of an abbreviation with the final letter superscript and a dot beneath it (though still "suspended" above where a full stop would go). Another use of the suspension mark can be seen in examples such as the "c" in "Mc" (e.g., the Rand McNally logo). It should be distinguished from the "mark of suspension", or tilde.
Acronyms and initialisms
In acronyms and initialisms, full stops are somewhat more often placed after each initial in American English (for example, U.S. and U.S.S.R.) than in British English (US and USSR), but this depends much upon the house style of a particular writer or publisher. The American Chicago Manual of Style now deprecates the use of full stops in acronyms.
The glyph has two alternative uses with regard to numbers. It can be used either as a decimal separator or to present large numbers in a much more readable form. The former use is more prevalent in English-speaking countries. In much of Europe, Southern Africa, and Latin America (with the exception of Mexico due to the influence of the United States), a comma is used as a decimal separator, while a full stop or a space is used for the presentation of large numbers. The following are examples where the comma is or would be used as a decimal separator:
1.002,003 or 1 002,003 (One thousand and two and three thousandths)
1.002.003 or 1 002 003 (One million two thousand and three)
In countries that use the comma as a decimal separator, the full stop is sometimes found as a multiplication sign; for example, 5,2 . 2 = 10,4. This usage is impractical in cases where the full stop is used as a decimal separator, hence the use of the interpunct: 5.2 · 2 = 10.4. This notation is also seen when multiplying units in science; for example, 50 km/h could be written as 50 km·h−1.
The traditional convention in American English and in Canada is "aesthetic" punctuation, or "typesetters' quotation", where full stops and commas are included inside quotation marks even if they are not part of the quoted sentence. The style used in the UK, and to a lesser extent in the U.S., is "logical punctuation", which stays true to the punctuation used by the original source, placing commas and full stops inside or outside quotation marks depending on where they were placed in the material that is being quoted. Scientific and technical publications, including in the U.S., almost universally use it for that reason.
The aesthetic or typesetter's rule was standard in early 19th-century Britain; its application was advocated, for example, in the influential book The King's English by Fowler and Fowler.
"Carefree" means "free from care or anxiety." (aesthetic or typesetters' style)
"Carefree" means "free from care or anxiety". (logical style used here because the full stop was not part of the original quotation)
Before the advent of mechanical type, the order of quotation marks with full stops and commas was not given much consideration. The printing press required that the easily damaged smallest pieces of type for the comma and full stop be protected behind the more robust quotation marks.[unreliable source?] Typesetters' style still adheres to this older tradition in formal writing. It is taught to American schoolchildren when they learn how to draft prose, and is strictly observed in most books, newspapers, magazines, and journals.
Two word spaces (English Spacing). It is sometimes claimed that the two-space convention stems from the use of the monospaced font on typewriters, but in fact that convention replicates much earlier typography — the intent was to provide a clear break between sentences. This spacing method was gradually replaced by the single space convention in published print, where space is at a premium, and continues in much digital media.
One widened space (such as an em space). This spacing was seen in historical typesetting practices (until the early twentieth century). It has also been used in other typesetting systems such as the Linotype machine and the TeX system. Modern computer-based digital fonts can adjust the spacing after terminal punctuation as well, creating space slightly wider than a standard word space.
Full stops in other scripts
In some Asian languages, notably Chinese and Japanese, a small circle is used instead of a solid dot: "。" (U+3002 "Ideographic Full Stop"). Notably, in Taiwan, Hong Kong, and Macao usage, the full stop is written at center height instead of on the line.
In the Devanagari script, used to write Hindi and Sanskrit among other Indian languages, a vertical line ("।") (U+0964 "Devanagari Danda") is used to mark the end of a sentence. In Hindi, it is known as poorna viraam (full stop) in Hindi and 'Daa`ri' in Bengalee. Some Indian languages also use the full stop, such as Marathi. In Tamil it is known as "Mutrupulli", which means End Dot.
In Sinhala, it is known as kundaliya:"෴ " ((U+0DF4) symbol "full stop"). Periods were later introduced into Sinhala script after the introduction of paper due to the influence of Western languages. Sinhala numerals
In Thai, no symbol corresponding to the full stop is used as terminal punctuation. A sentence is written without spaces, and a space is typically used to mark the end of a clause or sentence.
In the Ge'ez script used to write Amharic and several other Ethiopian and Eritrean languages, the equivalent of the full stop following a sentence is the ˈarat nettib (።) which means "four dots". The two dots on the right are slightly ascending from the two on the left, with space in between them.
Use in telegrams
The term STOP was used in telegrams in place of the full stop. The end of a sentence would be marked by STOP, because punctuation cost extra.
The character is encoded at U+002E.full stop (HTML: .).
In computing, the full stop is often used as a delimiter (commonly called a "dot"), such as in DNS lookups, web addresses, and file names:
It is used in many programming languages as an important part of the syntax. C uses it as a means of accessing a member of a struct, and this syntax was inherited by C++ as a means of accessing a member of a class or object. Java and Python also follow this convention. Pascal uses it both as a means of accessing a member of a record set (the equivalent of struct in C), a member of an object, and after the end construct which defines the body of the program. In Erlang, Prolog, and Smalltalk, it marks the end of a statement ("sentence"). In a regular expression, it represents a match of any character. In Perl and PHP, the full stop is the string concatenation operator. In the Haskell standard library, the full stop is the function composition operator.
In file systems, the full stop is commonly used to separate the extension of a file name from the name of the file. RISC OS uses full stops to separate levels of the hierarchical file system when writing path names—similar to / in Unix-based systems and \ in MS-DOS-based systems.
In Unix-like operating systems, some applications treat files or directories that start with a full stop as hidden. This means that they are not displayed or listed to the user by default.
^The term full stop for the term of punctuation is rarely used by speakers in Canada and virtually never in the United States. In American English, the phrase "full stop" is generally used only in the context of transport to describe the process of completely halting the motion of a vehicle. See, e.g., Seaboard Air Line Railway Co. v. Blackwell, 244 U.S.310 (1917) "under the laws of the state a train is required to come to a full stop 50 feet from the crossing"; Chowdhury v. City of Los Angeles, 38 Cal. App. 4th 1187 (1995) "Once the signals failed, the City could reasonably foresee that motorists using due care would obey the provisions of the Vehicle Code and make a full stop before proceeding when it was safe to do so".
^Truss, Lynn (2004). Eats, Shoots & Leaves: The Zero Tolerance Approach to Punctuation. New York: Gotham Books. p. 25. ISBN1-59240-087-6.
^Cindy Barden Grammar, Grades 4-5 2007 p9 "Use a period after a person's initials. Examples: A. A. Milne L.B.Peep W157 Use Periods With Initials Name. Initials are abbreviations for parts of a person's name. Date: Add periods at the ends of sentences, after abbreviations, and after initials".
^The Brief Thomson Handbook David Blakesley, Jeffrey Laurence Hoogeveen - 2007 -p477 "Use periods with initials: George W. Bush Carolyn B. Maloney
^New Hart's Rules: The handbook of style for writers and editors. Oxford University Press, 2005. ISBN0-19-861041-6.
^Oxford A–Z of Grammar and Punctuation by John Seely.
^Einsohn, Amy (2006). The Copyeditor's Handbook: A Guide for Book Publishing and Corporate Communications (2nd ed.). Berkeley, Los Angeles, London: University of California Press. p. 113. ISBN978-0-520-24688-1.
^Felici, James (2003). The Complete Manual of Typography: A Guide to Setting Perfect Type. Berkeley, CA: Peachpit Press. p. 80. ISBN0-321-12730-7.; Bringhurst, Robert (2004). The Elements of Topographic Style (3.0 ed.). Washington and Vancouver: Hartley & Marks. p. 28. ISBN0-88179-206-3.
^See for example, University of Chicago Press (1911). Manual of Style: A Compilation of Typographical Rules Governing the Publications of The University of Chicago, with Specimens of Types Used at the University Press (Third ed.). Chicago: University of Chicago. p. 101. ISBN1-145-26446-8.
^Mergenthaler Linotype Company (1940). Linotype Keyboard Operation: Methods of Study and Procedures for Setting Various Kinds of Composition on the Linotype. Mergenthaler Linotype Company. ASINB000J0N06M. cited in Mark Simonson (5 March 2004). "Double-spacing after Periods". Typophile. Typophile. Retrieved 5 April 2010.
^Felici, James (2003). The Complete Manual of Typography: A Guide to Setting Perfect Type. Berkeley, CA: Peachpit Press. p. 80. ISBN0-321-12730-7.; Fogarty, Mignon (2008). Grammar Girl's Quick and Dirty Tips for Better Writing (Quick and Dirty Tips). New York: Holt Paperbacks. p. 85. ISBN978-0-8050-8831-1.; Straus, Jane (2009). The Blue Book of Grammar and Punctuation: An Easy-to-Use Guide with Clear Rules, Real-World Examples, and Reproducible Quizzes (10th ed.). San Francisco, CA: Jossey-Bass. p. 52. ISBN978-0-470-22268-3.