UDC Fact Sheet


Offical NameUniversal Decimal Classification
DescriptionThe Universal Decimal Classification (UDC) is a document indexing language in the form of a classification scheme covering the whole universe of knowledge. The UDC is designed for subject description and indexing of content of information resources irrespective of the carrier, form, format or language
Last Release UDC MRF12 (December 2018)
Next Release UDC MRF13 (planned release 2023)
Updates/FrequencyAnnual: a new version of the scheme is released annually, containing extensions and corrections
Size 72,000 subdivisions
Languages 57 languages (varying extent of detail)
International Use 135 countries, 150,000-250,000 document collections worldwide
Application AreasLibraries, bibliographic databases, bibliographies, documentation services, information portals, online databases, publishing (e.g. journal articles)
Type of Classification Analytico-synthetic & faceted classification
Subject Coverage All areas of knowledge (disciplines, subdisciplines, subjects). See Subject coverage statistics
Knowledge PresentationBased on disciplines (subdivided hierarchically) with synthetic features; the UDC schedules are organized as a coherent system of knowledge with associative relationships and references between concepts and related fields
Vocabulary Organization Classes are organized in the tables of common concepts (context-free concepts) and in tables of main knowledge subdivisions subject classes
Type of NotationNumerals (decimal), symbols and letters of the alphabet as alphabetical extensions. Notation is hierarchically and syntactically expressive: the longer the number, the deeper the hierarchy, components in complex expressions are indicated by symbols and punctuation
Ownership of Copyright UDC Consortium, The Hague
MaintenanceUDC Consortium: UDC Editorial Team
DistributionUDC Consortium and licensed publishers
Contactmail@udcc.org; http://www.udcc.org
Associated PublicationsExtensions & Corrections to the UDC (ISSN: 0014-5424)
Copyright RestrictionUDC use in document indexing is free and unlimited in any context (libraries, bibliographic services, Internet, commercial-non commercial). The distribution and publishing of UDC content in the form of schedules whether in their entirety or as a subset are restricted to holders of a publishing licence
Online Schedules 
free access:Multilingual UDC Summary
UDC linked data
Croatian: Hrvatski UDK Online
Czech: České MDT Online
Polish: Polska UKD Online
Serbian: Српски УДК Онлајн
Slovakian: Slovenské MDT Online
paid subscription: English: UDC Online English
Dutch: UDC Online Nederlands
French: CDU Online Français
Spanish: CDU Online en Español
French: CDU Online Français
Slovenian: Univerzalna Decimalna Klasifikacija - UDCMRF12
Data FormatMaintained in database (mySQL, standard release is in English language distributed as a file to publishers and users, tagged text exports, XML exports.