Dot-decimal notation

IPv4 address

Dot-decimal notation is common in the form of dotted-quad notation to represent IPv4 addresses.{{cite web |access-date=2010-11-18

An IPv4 address has 32 bits. For purposes of representation, the bits may be divided into four octets written in decimal numbers, ranging from 0 to 255, concatenated as a character string with full stop delimiters between each pair of numbers.

For example, the address of the loopback interface, usually assigned the host name localhost, is 127.0.0.1. It consists of the four octets (written in binary notation) 01111111, 00000000, 00000000, and 00000001. The 32-bit number is represented in hexadecimal notation as 0x7F000001.

No formal specification of this textual IP address representation exists. The first mention of this format in RFC documents was in RFC 780 for the Mail Transfer Protocol published May 1981, in which the IP address was supposed to be enclosed in brackets or represented as a 32-bit decimal integer prefixed by a pound sign. A table in RFC 790 (Assigned Numbers) used the dotted decimal format, zero-padding each number to three digits.{{cite IETF

A popular implementation of IP networking, originating in 4.2BSD, contains a function inet_aton() for converting IP addresses in character string representation to internal binary storage. In addition to the basic four-decimals format and 32-bit numbers, it also supported intermediate syntax forms of octet.24bits (e.g. 10.1234567; for Class A addresses) and octet.octet.16bits (e.g. 172.16.12345; for Class B addresses). It also allowed the numbers to be written in hexadecimal and octal representations, by prefixing them with 0x and 0, respectively. These features continue to be supported in some software, even though they are considered as non-standard. This means addresses with a component written with a leading zero digit may be interpreted differently in programs that do or do not recognize such formats.{{cite web |archive-url = https://web.archive.org/web/20061206211851/http://support.microsoft.com/kb/115388 |archive-date = 2006-12-06

A POSIX-conforming variant of inet_aton, the inet_pton() function, supports only the four-decimal variant of IP addresses.

IP addresses in dot-decimal notation are also presented in CIDR notation, in which the IP address is suffixed with a slash and a number, used to specify the length of the associated routing prefix. For example, 127.0.0.1/8 specifies that the IP address has an eight-bit routing prefix, and therefore the subnet mask 255.0.0.0.

OIDs

Object identifiers use a style of dot-decimal notation to represent an arbitrarily deep hierarchy of objects identified by decimal numbers.

Version numbers

Software releases are often given version numbers in dot-decimal notation, with the left-most number designating the major version and any number of subsequent numbers designating less significant identities such as minor version, revision and build. A version number with a zero for the major part, e.g. 0.10.8, conventionally indicates a development version that has never been released (specifically the ninth sub-minor version of the eleventh minor version of the pre-release development work), reserving 1 for the first proper release.

Libraries

Libraries use notation systems consisting of decimal numbers separated by dots, such as the older Dewey Decimal Classification and the Universal Decimal Classification (UDC), to classify books and other works by subject. The UDC additionally codes works with multiple dot-decimal topics, separated by colons.

Medicine

File:Phalanges of left foot - animation01.gif File:Phalanges of left foot - animation02.gif Toe bones or phalanges of the foot Dot-decimal notation is also used to describe illnesses in a language-neutral way. For instance, the AO Foundation/Orthopaedic Trauma Association (AO/OTA) classification generates numeric codes for describing broken toes. There are other classifications for other fractures and dislocations.

References

References

1. (2021-04-05). "Gepunktete Dezimalschreibweise".
2. "What is Dotted Decimal Notation? - Definition from Techopedia".
3. "IPv4 and IPv6 address formats".
4. "Definition of dot address".
5. {{man. 3. inet_pton. die.net
6. Taylor, Arlene G.. (2005). "Introduction to Cataloging and Classification". Preprint, to be published by Libraries Unlimited in 2006.
7. (November 2020). "Hallux Proximal Phalanx Fracture in Adults: An Overlooked Diagnosis". Acta Ortopedica Brasileira.
8. (January 2018). "Fracture and Dislocation Classification Compendium-2018". Journal of Orthopaedic Trauma.