Vertical bar

:"Note: "broken bar" and the glyph "¦" redirect here."

The vertical bar (|) has various names including the pipe (by the Unix community), verti-bar, vbar, vertical line, vertical slash, or divider line by others. It has various usages in mathematics, where it can be used to represent absolute value, among others; computing and programming; and general typography, as a divider not unlike the interpunct.

The broken bar (¦) is a separate character.

The typical keyboard layout used in the United Kingdom features separate keys for vertical bar and broken bar; however, typically on Windows PCs the vertical bar key produces a broken-bar symbol and vice versa. North American keyboards typically have a key bearing a broken-bar symbol, which produces a vertical bar.

Etymology

The name "pipe" for the character "|" was a natural consequence of its usage in Unix shells, where it is used to notate the usage of the I/O pipeline construct.

Usage

Mathematics

The vertical bar is used as a mathematical symbol in
* absolute value: $|x|$, read "the absolute value of x".
* norms: $|(x\_1,x\_2)|$, read "the norm of x sub one, x sub two"; though Unicode also provides a special double vertical line symbol U+2016: ). Since these are technically letters, they have their own Unicode code points in the Latin Extended-B range: U+01C0 for the single bar and U+01C1 for the double bar. Longer single and double vertical bars are used to mark prosodic boundaries in the IPA.

Encoding

Despite the vertical bar being an accessible keystroke on typical North American and UK keyboards, there are cases where Web designers, Wiki editors, computer programmers, and others need to encode the vertical bar — usually because the vertical bar is a special symbol in their source code and yet a literal vertical bar needs to be displayed to the end user.

Set forth in 1963, American Standard Code for Information Interchange (ASCII-1963), one of the first widely used character maps, only had 69 display ("printable") characters; A–Z and 0–9 account for 36 of those characters. Vertical bar ("|") is the ASCII-1963 character at position 124 (decimal). Broken bar ("¦") is not part of the ASCII character set (any version) but a separate character that appeared (along with vertical bar) first in the EBCDIC family of character sets, and was copied from there into ISO 8859-1 and Unicode. The typical computer keyboard used in the United Kingdom features separate keys for "vertical bar" and "broken bar"; however most UK keyboard drivers today map both keys onto the ASCII character "vertical bar", as "broken bar" has hardly any practical application.

In common character maps

;Unicodehexadecimal (base-16): 007C

;UTF-8hexadecimal: 7C

;ASCIIdecimal (base-10): 124, or hexadecimal: 7C

;ISO/IEC 8859-1hexadecimal: 7C

;Shift-JIS Men-Ku-Ten1-01-35

;EBCDIC (CCSID 500 variant)hexadecimal: BB