Unicode Explained

One of the original ideas was to use the low line for underlining text using overprinting.

This is irrelevant these days, but the character might be used to create a horizontal line

in plain text. It depends on the font whether successive underline characters are joined

(____) or not (_ _ _ _).

Number sign # (U+0023)

The name of this character reflects its use to mean “number,” as in “item #42”

(meaning “item number 42, the 42nd item”). Such usage is mostly limited to U.S. Eng-

lish. More often, the word “number” is abbreviated as nr., no., n., or N

o

. In U.S. English,

the character is sometimes used to denote pound as a unit of weight (mass)—e.g., in

the paper industry “70#” means “70 lb.”

In computer languages, this character has many different uses, and it is usually called

a hash. In some of these uses, it relates to ordinal numbers. For example in HTML and

XML, &# n ; denotes the character that occupies code position n in Unicode. Mostly

the # character is just a separator (e.g., indicating the rest of the line as comment) or

has some special meaning assigned to it more or less arbitrarily, with no connection

with numbering. It is used in web addresses (URL references), and the URL syntax

specification calls it “crosshatch” character. Many other names are used as well, such

as “octothorpe.”

The number sign character unambiguously occupies code position 23 hexadecimal in

ISO Latin 1 and ...