ABSTRACT
The main classes have a two-digit notation, with subdivisions extending to a further two, and sometimes three digits after the decimal point. The above example illustrates the progressive process of division in an enumerative scheme. However, even in a simple scheme, this process,
and especially the consistent application of a particular characteristic of division at one point, is not easy, as the following schedule illustrates:
40 Statistics. Yearbooks 41 Social welfare 42 Crimes. Police 43 Prisons 44 Laws. Courts 45 Markets 47 Medicine. Hospitals 46 Public health and lighting 48 Transport. Traffic 49 Education
Example 6.3 ACM Computing Classification System (1998) (1999 – valid through 2009) 1 This scheme is a revision of the classification system used in the periodical Computing Reviews, which itself draws heavily on Taxonomy of Computer Science and Engineering. The heart of the classification is a hierarchical tree, ‘restricted to three levels in order [it is claimed] that the tree be able to reflect accurately the essential structure of the discipline over an extended period’ (ACM, Intro., p. 1). The top level consists of eleven classes identified by capital letters:
A. General Literature B. Hardware C. Computer Systems Organisation D. Software E. Data F. Theory of Computation G. Mathematics of Computing H. Information Systems I. Computing Methodologies J. Computer Applications K. Computing Milieux
The second and third levels make use of a numeric, decimal division, plus a lower case ‘m’ for ‘Miscellaneous’. In H. ‘Information systems’, for example, we find: H.0 GENERAL H.1 MODELS AND PRINCIPLES
H.1.0 General H.1.1 Systems and Information Theory
H.1.2 User/Machine Systems H.1.m Miscellaneous
H.2 DATABASE MANAGEMENT H.2.0 General
H.2.1 Logical Design H.2.2 Physical Design H.2.3 Languages H.2.4 Systems H.2.5 Heterogeneous Databases H.2.6 Database Machines H.2.7 Database Administration H.2.8 Database Applications H.2.m Miscellaneous H.3 INFORMATION STORAGE AND RETRIEVAL H.3.0 General
and so on In order to provide sufficient detail, there is also a fourth, unnumbered level which consists of alphabetical subject descriptors. Under H.2.1 ‘Logical Design’, for instance: H.2.1 Logical Design Data models Normal forms Schema and subschema In addition to these subject descriptors, there are general terms, such as ‘Algorithms’, ‘Design’, and ‘Documentation’, which can apply to any element when relevant. Names of languages of systems may also be used where appropriate, eg: ‘Pascal’ under D.3.2 ‘Language Classification’. Example 6.4 Dewey Decimal Classification (Dewey, 2003) This is a classification that covers the whole of knowledge. It was devised over a hundred years ago for shelf arrangement in libraries. It has since progressed through twenty-two editions. Its popularity can be gauged by the fact that it is used in over 200,000 libraries in 135 countries and has been translated into over thirty languages.2 Because it employs a simple, decimal notation, there are ten main classes:
000 Computer science, information & general works 100 Philosophy & psychology 200 Religion 300 Social sciences 400 Language
500 Science
600 Technology 700 Arts & recreation 800 Literature 900 History & geography Each main class can be divided into ‘ten’, in practice nine, subclasses and each subclass into nine more, and so on. Here, for example, are some parts of the Literature class, which the reader will see equate closely to the scheme shown on page 40-1, although the notation is different:
800 Literature . . .
