Subject Coverage

Because of the UDC's analytico-synthetic nature the number of subdivisions does not always reflect the true level of detail with which one can describe a document's content. Nevertheless, potential UDC users are often interested in the number of available classes in certain subject areas.

The pie chart on this page is a graphical representation of the distribution of subjects in the current MRF database (over 70,000 in 2012). The graph illustrates how much space pure sciences and technology, classes 5 and 6, occupy in the system. Another notable feature of the UDC concept distribution is the amount of common auxiliaries (coloured in grey) which are context-free concepts that are provided to be combined with all fields of knowledge.

The table below details the number of UDC subdivisions per subject area. The statistics reflect class distribution in the 2012 MRF database.

TableDescription (shortened)Count
Common auxiliaries 
IcCommon auxiliaries of language (Table 1c)1625
IdCommon auxiliaries of form (Table 1d)362
IeCommon auxiliaries of place (Table 1e)10942
IfCommon auxiliaries of human ancestry, ethnic grouping and nationality (Table 1f)37
IgCommon auxiliaries of time (Table 1g)454
IkCommon auxiliaries of properties (Table 1k -02)830
IkCommon auxiliaries of Materials (Table 1k -03)152
IkCommon auxiliaries of Relations, processes (Table 1k -04)338
IkCommon auxiliaries of Persons (Table 1k -05)270
Main table 
0KNOWLEDGE. MANAGEMENT. COMPUTER SCIENCE. INFORMATION...1810
004Computer science and technology. Computing. Data processing794
005Management284
1Philosophy. Psychology825
159.9Psychology293
2Religion2397
3Social Sciences6797
30General. Statistics. Sociology. Demography. Politics251
311Statistics as a science. Statistical theory41
314Demography. Population studies36
316Sociology384
32Politics253
33Economics1988
34Law1830
35Public Administration. Government872
36Public Welfare579
37Education229
39Folklore. Etnography194
5Mathematics. Natural Sciences12623
50Environment science49
51Mathematics1661
52Astronomy617
53Physics1876
54Chemistry. Mineralogical Sciences3280
55Earth Sciences1452
56/59Palaeontology. Biological Sciences3687
6Applied Sciences. Medicine. Technology27231
60Biotechnology42
61Medical Sciences3170
62Technology in general. Heat Engines. Hydraulics10313
621.3Electrical Engineering1699
621.4/.6Heat Engines. Pneumatic Energy. Fluids Handling478
621.7/.9Mechanical Technology1487
622Mining680
623Military Engineering618
624/627Civil Engineering1519
628Public Health Engineering479
629Transport Vehicle Engineering1781
63Agricultural Sciences2286
64Home Economics388
65Communication and transport industries. Accountancy. Business management. Public relations1384
654Telecommunication and telecontrol (organization, services)96
655Graphic industries. Printing. Publishing. Book trade213
656Transport and postal services. Traffic organization and control501
657Accountancy177
658Business management, administration. Commercial organization252
659Publicity. Information work. Public relations144
66Chemical Technology4327
67/68Various Industries and crafts4615
69Building (construction) trade. Building materials. Building practice and procedure705
7THE ARTS. RECREATION. ENTERTAINMENT. SPORT2608
71Physical planning. Regional, town and country planning. Landscapes, parks, gardens134
72Architecture115
73Plastic arts39
74Drawing. Design. Applied arts and crafts68
75Painting14
76Graphic art, printmaking. Graphics13
77Photography and similar processes722
78Music371
79Recreation. Entertainment. Games. Sport882
791Cinema. Films (motion pictures)128
792Theatre. Stagecraft. Dramatic performances83
793Social entertainments and recreations. Art of movement. Dance19
794Board and table games (of thought, skill and chance)39
796/799Sport612
8LANGUAGE. LINGUISTICS. LITERATURE849
80General questions relating to both linguistics and literature. Philology84
81Linguistics and languages417
82Literature347
9GEOGRAPHY. BIOGRAPHY. HISTORY458
902/908Archaeology. Prehistory. Cultural remains. Area studies52
91Geography. Exploration of the Earth and of individual countries. Travel. Regional geography77
92Biographical studies. Genealogy. Heraldry. Flags68
929Biographical studies67
930Science of history. Historiography10
94General history249