There are many different numbering schemes for assigning nominal numbers to entities. These generally require an agreed set of rules, or a central coordinator. The schemes can be considered to be examples of a

primary key In the relational model of databases, a primary key is a ''specific choice'' of a ''minimal'' set of attributes (Column (database), columns) that uniquely specify a tuple (Row (database), row) in a Relation (database), relation (Table (database), t ...

of a

database management system In computing, a database is an organized collection of data stored and accessed electronically. Small databases can be stored on a file system, while large databases are hosted on computer clusters or cloud storage. The design of databases span ...

table, whose table definitions require a

database design Database design is the organization of data according to a database model. The designer determines what data must be stored and how the data elements interrelate. With this information, they can begin to fit the data to the database model.Teorey, ...

. In

computability theory Computability theory, also known as recursion theory, is a branch of mathematical logic, computer science, and the theory of computation that originated in the 1930s with the study of computable functions and Turing degrees. The field has since e ...

, the simplest

numbering There are many different numbering schemes for assigning nominal numbers to entities. These generally require an agreed set of rules, or a central coordinator. The schemes can be considered to be examples of a primary key of a database management s ...

scheme is the assignment of natural numbers to a

set Set, The Set, SET or SETS may refer to: Science, technology, and mathematics Mathematics *Set (mathematics), a collection of elements *Category of sets, the category whose objects and morphisms are sets and total functions, respectively Electro ...

of objects such as functions, rational numbers, graphs, or words in some formal language. A numbering can be used to transfer the idea of computability and related concepts, which are originally defined on the natural numbers using computable functions, to these different types of objects. A simple extension is to assign cardinal numbers to physical objects according to the choice of some base of reference and of

measurement Measurement is the quantification of attributes of an object or event, which can be used to compare with other objects or events. In other words, measurement is a process of determining how large or small a physical quantity is as compared ...

units for counting or measuring these objects within a given precision. In such case, numbering is a kind of

classification Classification is a process related to categorization, the process in which ideas and objects are recognized, differentiated and understood. Classification is the grouping of related facts into classes. It may also refer to: Business, organizat ...

, i.e. assigning a numeric property to each object of the set to subdivide this set into related subsets forming a

partition Partition may refer to: Computing Hardware * Disk partitioning, the division of a hard disk drive * Memory partition, a subdivision of a computer's memory, usually for use by a single job Software * Partition (database), the division of a ...

of the initial set, possibly infinite and not enumeratable using a single natural number for each class of the partition. In some cases (such as computing, time-telling, and in some countries the numbering of floors in buildings) zero-based numbering is used, where the first entity is assigned "zero" instead of "one". Other numbering schemes are listed by field below.

Chemistry

CAS registry number A CAS Registry Number (also referred to as CAS RN or informally CAS Number) is a unique identification number assigned by the Chemical Abstracts Service (CAS), US to every chemical substance described in the open scientific literature. It inclu ...

s for chemical compounds * EC numbers for identifying enzymes * UN numbers for (classes of) hazardous substances *

E number E numbers ("E" stands for "Europe") are codes for substances used as food additives, including those found naturally in many foods such as vitamin C, for use within the European Union (EU) and European Free Trade Association (EFTA). Commonly ...

s for

food additive Food additives are substances added to food to preserve flavor or enhance taste, appearance, or other sensory qualities. Some additives have been used for centuries as part of an effort to preserve food, for example vinegar (pickling), salt (salt ...

Communications

*The E.164 numbering plan for telephone numbers, including: **

Country calling code Country calling codes or country dial-in codes are telephone number prefixes for reaching telephone subscribers in the networks of the member countries or regions of the International Telecommunication Union (ITU). The codes are defined by the ...

s ** North American Numbering Plan ** Numbering plans by country ***Argentina:

Argentine telephone numbering plan In Argentina, area codes are two, three, or four digits long (after the initial zero). Local customer numbers are six to eight figures long. The total number of digits is ten, for example, phone number (11) 1234-5678 for Buenos Aires is made up o ...

***Australia:

Australian telephone numbering plan The Australian telephone numbering plan describes the allocation of phone numbers in Australia. It has changed many times, the most recent major reorganisation by the Australian Communications & Media Authority taking place between 1994 and ...

***China:

China telephone numbering plan Telephone numbers in China are organized according to the Chinese Telephone Code Plan. The numerical formats of landlines and mobile phones are different: landlines have area codes, whereas mobile phones do not. In major cities, landline numbers ...

***France:

French telephone numbering plan The French telephone numbering plan is used in Metropolitan France, French overseas departments and some overseas collectivities. France uses a ten-digit closed numbering plan, where the first two digits denote a geographic area, mobile or non-g ...

***Hong Kong:

Hong Kong telephone numbering plan Telephone numbers in Hong Kong are mostly eight-digit. Fixed land line numbers start with 2 or 3, mobile (cellular) phone numbers with 5, 6, 7 or 9, pager numbers with 7 and forwarding service with 8. Since the end of 1989, there have been no a ...

***India: India telephone numbering plan ***Japan:

Japanese telephone numbering plan Telephone numbers in Japan consist of an area code, an exchange number, and a subscriber number. Dialing prefixes * 001, 00xx, 002xx, 0091xx Carrier selection prefix * 184 Prefix to withhold caller ID * 186 Prefix to provide caller ID Types o ...

***Singapore:

Singapore telephone numbering plan Telephone numbers in Singapore, also known as the National Numbering Plan, are regulated by the Info-communications Media Development Authority (IMDA). Due to the small geographical size of Singapore, there are no area or trunk codes; all numbers ...

***United Kingdom: UK telephone numbering plan ***Germany: German telephone numbering plan *The IP address allocation scheme (

IANA The Internet Assigned Numbers Authority (IANA) is a standards organization that oversees global IP address allocation, autonomous system number allocation, root zone management in the Domain Name System (DNS), media types, and other Interne ...

) *The DNIC prefixes of

X.25 X.25 is an ITU-T standard protocol suite for packet-switched data communication in wide area networks (WAN). It was originally defined by the International Telegraph and Telephone Consultative Committee (CCITT, now ITU-T) in a series of drafts a ...

NUAs (Network User Address) assigned by the

ITU The International Telecommunication Union is a specialized agency of the United Nations responsible for many matters related to information and communication technologies. It was established on 17 May 1865 as the International Telegraph Unio ...

* Object identifiers (OID)

Products

* The GS1 numbering scheme, including **

GTIN The Global Trade Item Number (GTIN) is an identifier for trade items, developed by the international organization GS1. Such identifiers are used to look up product information in a database (often by entering the number through a barcode scanne ...

for products, which includes the UPC and EAN-13 barcodes ** ISBN codes for books ** ISSN codes for periodicals * Vehicle identification number *

Stock keeping unit In inventory management, a stock keeping unit (abbreviated as SKU and pronounced or ) is the unit of measure in which the stocks of a material are managed. Or to put it another way; is a distinct type of item for sale, purchased, or tracked in ...

(SKU)

People

Identification numbers

*National identification numbers **

Personal Numeric Code (Romania) A national identification number, national identity number, or national insurance number or JMBG/EMBG is used by the governments of many countries as a means of tracking their citizens, permanent residents, and temporary residents for the purpo ...

** Personal identification number (Denmark) ** Social Security number (United States) ** Social Insurance Number (Canada) ** INSEE number (France) ** National Insurance number (United Kingdom) ** Aadhaar (India) *

Personal Public Service Number The Personal Public Service Number (PPS Number) ( ga, Uimhir Phearsanta Seirbhíse Poiblí, or ) is an identifier issued by the Client Identity Services section of the Department of Social Protection, on behalf of the Minister for Social Protect ...

(Republic of Ireland) *

Tax file number A tax file number (TFN) is a unique identifier issued by the Australian Taxation Office (ATO) to each taxpaying entity — an individual, company, superannuation fund, partnership, or trust. Not all individuals have a TFN, and a business has both ...

(Australia) * Unique Master Citizen Number (former Yugoslavia) *

Det Centrale Personregister Det Centrale Personregister (CPR; kl, Inunnik Qitiusumik Nalunaarsuiffik, en, Civil Registration System) is the Realm of Denmark's nationwide civil registry. Established in 1968, the registry contains the name, address, Danish personal identifi ...

(Denmark)

Ordinals for names

* Regnal numbers **

Princes of Reuss Reuss (german: Reuß , ) was the name of several historical states located in present-day Thuringia, Germany. Several lordships of the Holy Roman Empire which arose after 1300 and became Imperial Counties from 1673 and Prince of the Holy Roman Em ...

** Popes' ordinals * Generational ordinal suffix to names

Topics

* Dewey Decimal Classification and Universal Decimal Classification for books * West American Digest System legal topic numbering scheme

Geography and transport

* Postal codes ** ZIP codes * Geocodes (used also as ''fine-grained postal codes''): ** Geohash ** Open Location Code * Global Location Numbers by GS1 * FIPS place codes * House numbering schemes *

Floor numbering A storey (British English) or story (American English) is any level part of a building with a floor that could be used by people (for living, work, storage, recreation, etc.). Plurals for the word are ''storeys'' (UK) and ''stories'' (US). T ...

* Room number * Line number * See also: Country code; Address (geography).

Vehicles

* Vehicle registration plates *

British Carriage and Wagon Numbering and Classification A number of different numbering and classification schemes have been used for carriages and wagons on Britain's railways, and this page explains the principal systems. Carriages and wagons (either not self-propelled, or part of a multiple unit wh ...

* British Rail locomotive and multiple unit numbering and classification *

UIC classification of goods wagons This list contains the UIC classification of goods wagons and their meanings. The description is made up of a category letter (in capitals) and usually several index letters (in lower case). The international system for the classification of good ...

Roads

Road numbering scheme A road is a linear way for the conveyance of traffic that mostly has an improved surface for use by vehicles (motorized and non-motorized) and pedestrians. Unlike streets, the main function of roads is transportation. There are many types of ...

s *

Arlington County, Virginia, street-naming system This article details the street-naming system of Arlington County, Virginia in the United States. Although the streets of Arlington County are not laid out on a grid plan, its local streets follow sequential numbered or alphabetic patterns tha ...

China road numbering A route (or road) number, designation or abbreviation is an identifying numeric (or alphanumeric) designation assigned by a highway authority to a particular stretch of roadway to distinguish it from other routes and, in many cases, also to indica ...

* Great Britain road numbering scheme * European route by UNECE *

Numbered highways in the United States Highways in the United States are split into at least four different types of systems: Interstate Highways, U.S. Highways, state highways, and county highways. Highways are generally organized by a route number or letter. These designations are ge ...

* Edmonton, Alberta#Street layout * Montreal * Highways in Australia#Route numbering systems

Others/general

API well numbers An API well number or API number is a "unique, permanent, numeric identifier" assigned to each oil well, well drilled for oil and gas in the United States.American Petroleum Institute, 1979, The API well number and standard state and county numeric ...

for numbering oil and gas

wells Wells most commonly refers to: * Wells, Somerset, a cathedral city in Somerset, England * Well, an excavation or structure created in the ground * Wells (name) Wells may also refer to: Places Canada *Wells, British Columbia England * Wells ...

in the United States * Bank card number * International Bank Account Number *

International Geo Sample Number The International Generic Sample Number or IGSN is a persistent identifier for sample. As an active persistent identifier it can be resolved through the Handle System. The system is used in production by the System for Earth Sample Registration (S ...

(IGSN) *

International Statistical Classification of Diseases and Related Health Problems The International Classification of Diseases (ICD) is a globally used diagnostic tool for epidemiology, health management and clinical purposes. The ICD is maintained by the World Health Organization (WHO), which is the directing and coordinating ...

for diseases *The MAC address allocation scheme for hardware addresses of certain networking products * National Animal Identification System *

National Pokédex National may refer to: Common uses * Nation or country ** Nationality – a ''national'' is a person who is subject to a nation, regardless of whether the person has full rights as a citizen Places in the United States * National, Maryland, ce ...

*The

NSAP A Network Service Access Point address (NSAP address), defined in ISO/IEC 8348, is an identifying label for a Service Access Point (SAP) used in OSI networking. These are roughly comparable to IP addresses used in the Internet Protocol; they can s ...

allocation scheme *

Post office box A post office box (commonly abbreviated as P.O. box, or also known as a postal box) is a uniquely addressable lockable box located on the premises of a post office. In some regions, particularly in Africa, there is no door to door delivery ...

Production code number A production code number, also known as the production code (PC) or episode code is an alphanumeric designation used to uniquely identify episodes within a television series. It is also broadly used for other identification purposes where a unique ...

Stamp numbering system Philatelists' traditional method of identifying postage stamps uniquely has long been to number each country's stamps consecutively; Norway #1 is the 4-skilling blue stamp issued in 1855, and so forth. However, this seemingly straightforward numbe ...

* Wikipedia markup syntax for numbered lists

References

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