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Alphanumeric is a combination of alphabetic and numeric characters, and is used to describe the collection of Latin letters
Latin alphabet
The Latin alphabet, also called the Roman alphabet, is the most recognized alphabet used in the world today. It evolved from a western variety of the Greek alphabet called the Cumaean alphabet, which was adopted and modified by the Etruscans who ruled early Rome...

 and Arabic digits
Arabic numerals
Arabic numerals or Hindu numerals or Hindu-Arabic numerals or Indo-Arabic numerals are the ten digits . They are descended from the Hindu-Arabic numeral system developed by Indian mathematicians, in which a sequence of digits such as "975" is read as a numeral...

 or a text constructed from this collection. There are either 36 (single case) or 62 (case-sensitive) alphanumeric characters. The alphanumeric character set consists of the numbers 0 to 9 and letters A to Z. In the perl programming language, the underscore character ( _ ) is also considered to be a member of the alphanumeric set of characters.


In computing terminology, a character stored in alphanumeric form may potentially occupy less space than storing an 8-bit ASCII
The American Standard Code for Information Interchange is a character-encoding scheme based on the ordering of the English alphabet. ASCII codes represent text in computers, communications equipment, and other devices that use text...

 character, as each character requires only 6 bits for encoding.

There is no standard for storing 6-bit alphanumeric data. A 6-bit field has 64 possible values, so if only 36 are used in single case, there is room for another 28 characters (usually slashes and other punctuation), making alphanumeric data useful for storing text and website addresses
Uniform Resource Identifier
In computing, a uniform resource identifier is a string of characters used to identify a name or a resource on the Internet. Such identification enables interaction with representations of the resource over a network using specific protocols...


Subsets of alphanumeric used in human interfaces

When a string of mixed alphabets and numerals is presented for human interpretation, ambiguities arise. The most obvious is the similarity of the letters I, O and Q to the numbers 1 and 0. Therefore, depending on the application
Record locator
A record locator is an alphanumeric code, typically 6 characters in length, used in airline reservation systems to access a specific record. When a passenger, travel agent or airline employee refers to a record locator they typically mean a pointer to a specific reservation which is known as a...

, various subset
In mathematics, especially in set theory, a set A is a subset of a set B if A is "contained" inside B. A and B may coincide. The relationship of one set being a subset of another is called inclusion or sometimes containment...

s of the alphanumeric were adopted to avoid misinterpretation by humans.

In passenger aircraft, aircraft seat maps and seats were designated by row number followed by column letter. For wide bodied jets, the seats can be 10 across, labeled ABC-DEFG-HJK. The letter I is skipped to avoid mistaking it as row number 1.

In Vehicle Identification Number
Vehicle identification number
A Vehicle Identification Number, commonly abbreviated to VIN, is a unique serial number used by the automotive industry to identify individual motor vehicles. VINs were first used in 1954...

 used by motor vehicle manufacturers, the letters I, O and Q are omitted for their similarity to 1 or 0.

Tiny embossed letters are used to label pins on an V.35/M34 electrical connector. The letters I, O, Q, S and Z were dropped to ease eye strain with 1, 0, 5, and 2. That subset is named DEC
Digital Equipment Corporation
Digital Equipment Corporation was a major American company in the computer industry and a leading vendor of computer systems, software and peripherals from the 1960s to the 1990s...

 Alphabet after the company that first used it.

For alphanumerics that are frequently handwritten, in addition to I and O, V is avoided because it looks like U in cursive, and Z for its similarity to 2.

Other references

In the TV show ReBoot
ReBoot is a Canadian CGI-animated action-adventure cartoon series that originally aired from 1994 to 2001. It was produced by Vancouver-based production company Mainframe Entertainment, Alliance Communications, BLT Productions and created by Gavin Blair, Ian Pearson, Phil Mitchell and John Grace,...

, "alphanumeric" was an interjection used by Enzo as an equivalent of "cool!" or "awesome!" In the episode "Talent Night", it was used to mean "everything is all right."

External links