The Alphadecimal Library Classification System

The Alphadecimal Library Classification System (ALiCS)

The Alphadecimal Library Classification System is a system of classifying books in a library or collection, similar to other well-known systems such as Library of Congress or Dewey Decimal. I have long struggled to find a simple system to classify my small library of books that was not too complex, had memorable main class codes and was flexible enough to handle the specific "demographics" of the books in my library. I also wanted each book's call number to have the same number of symbols, as opposed to variable length of call numbers in other systems. I could have just used the three-digit main classes of the Dewey Decimal system, of course, but this would have meant that some classes would be too specific for subjects not present in my collection, and not specific enough for other subject. For example, I have a large number of sports books and I wanted the classes to be specific for different sports, but using Dewey all the sports books would have been under the same class.

I also wanted a system with letters at the beginning, as I find these more memorable than a purely numerical system. I initially used the Library of Congress (LOC) system, partly because, at the time (around the late 1990s), the Library of Congress was the only place with a comprehensive online search, which was also free to use. So, all my books were classified using this system.

There were a number of problems with this system, however. For one thing, the classifications were rather lengthy for the size of the library. Also, the resulting call numbers were of varying length and it was also difficult to class books that were not present in the Library of Congress catalogue. So, I was looking for a different system, with a fixed number of say five or six characters. I decided to devise one of my own but this is not an easy task, and I decided to use a system similar to the Dewey Decimal system as the base for mine.

The system I have devised is actually based upon the Free Decimal System (FDS), created by John Mark Ockerbloom. This is an open source system, works in a similar fashion to DDC, and is freely available. Also, there are now resources such as LibraryThing, through which catalogues of private and public libraries can be published, which uses its own system, the Melvil Decimal System, also based on FDS, and this can be accessed to help classify books.

So, I devised the ALiCS (a play on my own name 'Alex'), which stands for the Alphadecimal Library Classification System. The 'Alphadecimal' description refers to the fact the main classes are represented by two letters, and these are followed by three numbers to complete the basic classification for each book. The two letters correspond in most cases to the first two numbers in the FDS, in some classes they refer to the first three numbers. For example, whereas 'AR' (Architecture) represents the FDS class '72x', 'RS' (Sports and athletics) represents the class '796'. This is because of the high number of sports books that I have, as mentioned above. Indeed, the "Recreation and Amusements" class, which comes under "Arts" in the FDS, has its own main class in ALiCS.

How does it work?

As mentioned above, the main subject codes have been limited to five characters, which suits the small library and is easily fitted onto the spine of the books. However, expansion is allowed for by the addition of further codes, which provide further information in the index itself and a level of uniqueness for different works on the same subject. This is can be done in one of three ways:

  1. A Cutter number. This is a very flexible way of adding further information to the classification, requiring no lengthy special tables and is easy to devise.These are most often used for titles or author's names, e.g. GT411; N5 for "Scottish Place-names" by W. F. H. Nicolaisen, where the Cutter number N5 denotes the author's name. This method is characterised by a single letter followed by one or more digits in the range 2-9. (Cutter numbers are named after Charles Ammi Cutter, who devised them as part of his Expansive Classification).
  2. Standard subdivisions. Additional information can be added using tables of standard subdivisions, e.g. 421 denoting an area code for Greater London. For example, the book The Story of London's Underground by John R Day could be classified as ST842-421.
  3. Secondary classification. Some titles will have a secondary subject and this is denoted purely by adding that subject classification following the main one. For example, London Railway Atlas has the main class GM421 for a map or atlas of Greater London, followed by the secondary class ST500 for railways. The full code is GM421; ST500; B7. This method is characterised by two letters followed by three digits in the range 0-9.

ALiCS Main Classes

The following list shows the main classes in the ALiCS:

Class Subject FDS/MDS
A — Arts
AA General arts 700—709
AD Drawing; Decoration; Design 740—749
AF Photography 770—779
AG Graphic arts; Engraving 760—769
AL Landscape gardening 710—719
AM Music 780—789
AP Painting 750—759
AR Architecture 720—729
AS Sculpture 730—739
B — Literature
BA General literature 800—809
BE English literature 820—829
BF French literature 840—849
BG German literature 830—839
BH Greek literature; Classical literature 880—889
BL Latin literature 870—879
BN American literature 810—819
BR Italian literature; Romanian literature 850—859
BS Spanish literature; Portuguese literature 860—869
BY Literature of other languages 890—899
E — Religion
EA General religion 200—209
EB Bible 220—229
EC Christianity 230—289
EH Religions of Indic origin 294
EJ Judaism 296
EM Islam & Bahá'i faith 297
ET Natural theology 210—218
EY Other religions & comparative religion 290—293,
295, 299
H — History
HA General history 900—909
HB Biography 920—929
HC Ancient world 930—939
HE Europe 940—949
HF Africa 960—969
HG Geography & travels (for actual maps & atlases class under 'MA') 910—919
HN North America 970—979
HP Pacific & polar regions 990—999
HS South America 980—989
HV Asia 950—959
L — Language
LA General language 400—409
LB Linguistics 410—419
LE English 420—429
LF French 440—449
LG German; Germanic languages 430—439
LH Greek 480—489
LL Latin 470—479
LR Italian; Romanian 450—459
LS Spanish; Portuguese 460—469
LY Other languages 490—499
M — Maps & atlases
MA Maps & atlases (for books about maps & atlases class under 'HG') 912
N — Science & natural history
NA General science 500—509
NB Botany 580—589
NC Chemistry 540—549
NF Physics 530—539
NG Geology; Earth sciences 550—559
NL Life sciences 570—579
NM Mathematics 510—519
NP Palaeontology 560—569
NR Astronomy 520—529
NZ Zoology 590—599
P — Philosophy
PA General philosophy 100—109
PD Ideology; Philosophical systems 140—149
PE Ethics 170—179
PF Modern philosophy 190—199
PH Philosophy of humanity 120—129
PL Logic 160—169
PM Metaphysics 110—119
PN Ancient, mediaeval & eastern philosophy 180—189
PP Parapsychology 130—139
PS Psychology 150—159
R — Recreation & amusements
RA Amusements 790
RC Card games; Games of chance 795
RF Fishing; Hunting; Shooting 799
RG Games & indoor amusements 793
RH Horsemanship; Animal racing 798
RK Games of skill 794
RP Public entertainment 791
RQ Aquatic sports; Aerial sports 797
RS Sports & athletics 796
RT Theatre; Dance 792
S — Social sciences
SA General social sciences 300—307
SC Customs & folklore 390—399
SD Education 370—379
SE Economics 330—339
SG Statistics 310—319
SL Law 340—349
SM Public administration; Military science 350—359
SP Political science 320—329
SS Social service; Societies 360—369
ST Transport; Communications; Commerce 380—389
T — Technology
TA General technology 600—609
TB Building 690—699
TC Chemical technology 660—669
TE Engineering 620—629
TF Manufacturing 670—679
TG Agriculture 630—639
TH Home economics 640—649
TM Medicine 610—619
TP Occupations & handicraft 680—689
TX Business 650—659
Y — General works; Information
YA Anthologies; Quotations 080—089
YB Bibliography 010—017
YC Computing & information 000—006
YE Encyclopaedias 030—039
YJ Journalism; Newspapers 070—079
YL Library science 020—028
YP Periodicals 050—059
YR Rare books 090—099
YS Societies; Associations 060—069

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© Alex Middleton 2010. Updated 2017 with ALiCS version 1.0 standard.

This system is open source and it can be used or modified for personal purposes. An acknowledgement would be appreciated, however. ALiCS is based upon and takes much of its information from the Free Decimal System by John Mark Ockerbloom. MDS (Melvil Dewey System) is an adaptation of the FDS used by LibraryThing. The Dewey Decimal System mentioned on this page is the copyright of the OCLC.