Numbering scheme

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 system table, whose table definitions require a database design.

The simplest numbering scheme is to assign cardinal numbers to entities. 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 numbers for chemical compounds
EC numbers for identifying enzymes
UN numbers for (classes of) hazardous substances
E numbers for food additives

Communications

The E.164 numbering plan for telephone numbers, including:
- Country calling codes
- North American Numbering Plan
- Numbering plans by country
  - Argentina: Argentine telephone numbering plan
  - Australia: Australian telephone numbering plan
  - China: China telephone numbering plan
  - France: French telephone numbering plan
  - Hong Kong: Hong Kong telephone numbering plan
  - Japan: Japanese telephone numbering plan
  - Singapore: Singapore telephone numbering plan
  - United Kingdom: UK telephone numbering plan
  - Germany: German telephone numbering plan
The IP address allocation scheme (IANA)
The DNIC prefixes of X.25 NUAs (Network User Address) assigned by the ITU
Object identifiers (OID)

Products

The GS1 numbering scheme, including
- GTIN for products, which includes the UPC and EAN-13 barcodes
- ISBN codes for books
- ISSN codes for periodicals
Vehicle identification number
Stock keeping unit (SKU)