Number sign

Number sign is one name for the symbol #, and is the preferred Unicode name for the codepoint represented by that glyph. The symbol is similar to the musical symbol sharp (♯). Several names for this symbol are used in the United States and Canada. In most other English-speaking countries, it is called a hash.

The sign's Unicode codepoint is U+0023 and its ASCII value is 0x23 (hexadecimal).

In many parts of the world, including the United Kingdom, Canada, Australia, New Zealand, Russia, and the rest of Europe, "number sign" is the name of the "número" sign, № (Unicode codepoint U+2116), often written simply as No. or №. In these contexts, the # sign is not used to indicate a number or numerical value.

Naming convention within North America

In some regions of the United States and Canada, the symbol is traditionally called the pound sign, but in others, the number sign. This derives from a series of abbreviations for pound, which is a unit of weight. At first "lb." was used; however, printers later designed a font containing a special symbol of an "lb" with a line through the ascenders so that the lowercase letter "l" would not be mistaken for the number "1". Unicode character U+2114 (℔) is called the "LB Bar Symbol", and it is a cursive development of this symbol. Ultimately, there was the reduction to a combination of two horizontal strokes (cf. skewed "=") and two forward-slash-like strokes (cf. "//"). In this respect, names like fence or square — as well as the representation of the sign containing two vertical strokes (rather than slanted ones), as on many keyboards — are misleading.

Its traditional commercial use in the U.S. was such that when it followed a number, it was to be read as "pounds", as in 5# of sugar, and when it preceded a number, it was to be read as 'number', as in #2 pencil. Thus the same character in a printer's type case had two uses.

Other names in English

It has many other names (and uses) in English. (Those in bold are listed as alternative names in the Unicode documentation.)

• comment sign
  • from its use in many shell scripts and some programming languages like Perl to introduce comments

• crosshatch
  • resemblance

• fence, gate, grid, gridlet
  • resemblance

• hash / hash mark / hash sign
  • Hash is most common name for the mark used in the non-North American English-speaking world.
  • In Ireland, the UK, Australia, India and New Zealand, "hash key" refers to the # button on touch-tone telephones; "Please press the hash key."
  • The symbol is often used as medical shorthand for 'fracture'
  • Used among computer professionals. For example, in Unix scripting, it's used in combination with an exclamation mark ("#!") to produce a "shebang" or "hash-bang", used to tell the kernel which program to use to run the script.

• hex
  • from its use to denote hexadecimal values in some markup and programming languages

• mesh
  • introduced in the tonsil of the Intercal reference manual, and often reproduced in The Hacker's Dictionary

• octothorp / octothorpe / octathorp / octatherp
  • See wiktionary:octothorpe for etymology. With some detail at www.octothorp.us.
  • See Doug Kerr's Octatherp article for detailed alternate etymology of octotherp.
  • See Encore magazine article "Pressing matters: touch-tone phones spark debates" for another attribution to Bell engineers, by 1968. Lauren Asplund, who provided the article, says that he and a colleague were the source of octothorp at AT&T engineering in New York in 1964.
  • The Merriam-Webster New Book of Word Histories, 1991, has a long article that's consistent with Doug Kerr's essay, in that it says octotherp was the original spelling, and that the word arose in the 1960s among telephone engineers.
  • The first appearance of octothorp in a U. S. patent is in a 1973 filing which also refers to the asterisk (*) as a sextile.[1]
  • http://www.worldwidewords.org/weirdwords/ww-oct1.htm tells of three possible etymologies, none likely, and says it wasn't in print until 1974, so the Merriam-Webster story that says it appeared in the 1960s may be more credible.

• pound
  • Used as the symbol for the pound (the unit of mass) in the U.S. (where lb. would be used in the UK and Canada; note that lb. or lbs. is common in the U.S. as well and is used by the general public more often than #). It is never called the pound sign in the UK, where that term always denotes the symbol for pounds sterling (£) rather than that for pounds weight (lb).
    • Keith Gordon Irwin in, The Romance of Writing, p. 125 says: "The Italian libbra (from the old Latin word libra, 'balance') represented a weight almost exactly equal to the avoirdupois pound of England. The Italian abbreviation of lb with a line drawn across the letters was used for both weights. The business clerks' hurried way of writing the abbreviation appears to have been responsible for the # sign used for pound."
  • Used in the U.S. and Canada on touch-tone telephones – "Please press the pound key"

• sharp
  • resemblance to the glyph used in music notation, U+266F (♯). Since most fonts don't contain the sharp sign, many works use the fallback number sign.
  • so called in the name of the Microsoft-invented programming language, C#. However Microsoft says at Frequently Asked Questions About C#:
    It's not the "hash" (or pound) symbol as most people believe. It's actually supposed to be the musical sharp symbol. However, because the sharp symbol is not present on the standard keyboard, it's easier to type the hash ("#") symbol. The name of the language is, of course, pronounced "see sharp".
    According to the ECMA-334 C# Language Specification, section 6, Acronyms and abbreviations, the name of the language is written "C#" ("LATIN CAPITAL LETTER C (U+0043) followed by the NUMBER SIGN # (U+0023)") and pronounced "C Sharp".
  • In computing a shebang is the inexact contraction of sharp and bang the typical names of the # and ! signs used at the beginning of executable text files.

• space
  • used by editors to indicate where space should be inserted in a proof. This can mean (1) a line space (the space between two adjacent lines denoted by line # in the margin), (2) a hair space (the space between two letters in a word, denoted by hr #) (3) a word space, or letter space (the space between two words on a line, two letter spaces being ##). Em- and en-spaces (being the length of a letter m and n, respectively) are indicated by a square-shaped em- or en-quad character (  and  ̷, respectively).

• square
  • occasionally used in the UK (e.g. sometimes in BT publications and automatic messages) - especially during the Prestel era, when the symbol was a page address delimiter
  • the International Telecommunications Union specification ITU-T E.161 3.2.2 states: "The # is to be known as a 'square' or the most commonly used equivalent term in other languages."

Other uses

In a telephone keypad it is one of the two standard special keys beyond digits 0 to 9 (the other special key is the star key *). Pressing this # key, a compound tone mixing 941 Hz and 1477 Hz is sent to the line. Its special function depends on services provided by a given phone company.

In a URL the sign is used immediately after the URL of a webpage or other resource to introduce a "fragment identifier" – a name or id which defines a position within that resource or a section of the document. For example, in the URL http://en.wikipedia.org/wiki/Number_sign#Other_uses the portion after the # (Other_uses) is the fragment identifier (a link such as this will take you to a section in a web page, such as the 'In other languages' section of this article). A relative reference to the fragment from within the document itself can start with the number sign, and consist of just the fragment identifier: <a href="#top">TOC</a> refers to an anchor named "top" on the current web page. [2]

In the C preprocessor, as used in the C programming language and elsewhere, the sign is used to introduce preprocessor directives, as in #define MAX 25, for example.

In several assembly languages, the sign is used preceding an expression to denote an immediate value.

In writing press releases, the notation "###" indicates that there is no further copy to come.

In many countries, such as Norway, a "#" is used as a delimiter between different drugs on medical prescriptions. [3]

In chess, the # symbol represents checkmate.

In mathematics, # is sometimes used to denote the cardinality of a set.

In other languages

• Albanian: "diezis", (sharp), a loan from Greek.
• Arabic: "مربع", pronounced "morabaa" (square)
• Basque: Traol
• Bulgarian: диез, pronounced dies
• Catalan: Coixinet
• Chinese: "井號" (jǐng hào; literally: "well" sign) as it resembles the hanzi for water well, 井; jǐng
• Czech: mřížka (small grid or small bar)
• Danish: firkant (tetragon, i.e. square), the official name used by telcos for touch-tone key, or havelåge (garden gate from the gate in a picket fence)
• Dutch: hekje (fence), spoorwegteken (railroad sign), matje (mat), kardinaalteken (cardinal sign)
• Estonian: trellid (grate)
• Finnish: ristikkomerkki ("grid mark"), ruutu ("square") or risuaita ("brushwood fence")
• French: dièse in music (sharp sign) or cardinal in math (to represent cardinality). In Québec and Benelux it is called carré (square) in the context of a phone keyboard.
• German: Raute or Rautenzeichen (Rhombus, the official name used by telephone companies for the touch-tone key), Lattenzaun (picket fence), Doppelkreuz (double cross), Gatter (gate)
• Greek: δίεση (diesis -- the name of the music symbol)
• Hebrew: סוּלָמִית, pronounced sulamit (from sulam("ladder") + -it (diminutive))
• Hungarian: kettőskereszt (double cross, misleadingly the same word as the one for double dagger and patriarchal cross; only used in telephone service)
• Icelandic: ferkantur (square), kassi (box)
• Italian: cancelletto (small gate)
• Japanese: "番号記号" (bangōkigō, "number sign"); "井桁" (igeta, literally the rim of a well, which is traditionally this shape) or "シャープ" (sharp in katakana)
• Latvian: restīte [IPA: restiːte] (little grid)
• Lithuanian: grotelės [IPA: groːteleːs] (little grid)
• Norwegian: firkant (tetragon, i.e. square) or (sometimes) skigard (A particular kind of fence with a visual resemblance)
• Persian: "چهارگوش" (Four-Corner) pronounced "Chaa'haa'r Goo'sh"
• Polish: kratka, krzyżyk (sharp sign), płotek, hash
• Portuguese: cardinal, used in mathematics notation to represent the cardinality of a set, sustenido ("sharp sign"), jogo-da-velha or jogo-do-galo ("tic-tac-toe"). Also known as "cerquinha" in Brazil because it resembles a picket fence (cerca).
• Romanian: diez ("sharp sign")
• Russian: решётка (reshëtka), pronounced r'ee-SHOT-ka (means "grid"); in music диез (from French dièse), pronounced d'ee-YEZ (means "sharp sign")
• Serbian: тараба / taraba (fence)
• Slovak: mriežka ("small grid")
• Slovenian: lojtra (the official name used by telcos for the touch-tone key, a colloquial term for ladder)
• Spanish: numeral, cardinal, cuadradillo, almohadilla ("cushion"), michi, gato, tatetí (the last three meaning "tic-tac-toe")
• Swedish: stakettecken ("fence sign"), staket ("fence"), galler ("grid, grating") fyrkant ("square"), ruta ("square, box"), vedstapel ("stack of wood") or brädgård ("timberyard")
• Swiss German: Gartehag (fence)
• Thai: เครื่องหมายสี่เหลี่ยม (square sign, only used in telephone service)
• Turkish: Sayı işareti, also diyez, derived from Greek.

See also

• Numero sign
• Telephone keypad

External links

• wiktionary:Octothorpe for etymology.
• www.octothorp.us
• Doug Kerr's Octatherp article for detailed alternate etymology of octotherp.
• Encore magazine article "Pressing matters: touch-tone phones spark debates" for another attribution to Bell engineers.
• World Wide Words entry gives three possible etymologies
• Weird Words entry for this symbol.
• World Heritage Dictionary entry for this symbol.