National Library of Medicine Classification compared with Bliss class H

Abstract

A comparison of the National Library of Medicine Classification with class H of Bliss' Bibliographic Classification is made under three headings. Firstly the author's 12 criteria for judging classification schemes are used to compare these two schemes in detail. These criteria cover basis, order, universality, hospitality, adaptability, terminology, indication of relations, synthesis, notation, ease of use, revision and practical use. Bliss is shown to be superior in all except one aspect of notation. In the second part the twelfth criterion is used to compare the practical use of the schemes, a test file of 13 titles being classified by the two schemes and relative merits and disadvantages discussed. Bliss always gives specific if sometimes long class marks, but the National Library of Medicine Classification has the disadvantages of lack of specificity, lack of synthesis and two places for some subjects. The third part compares the indexes of the two schemes, showing that Bliss contains more indexing terms despite the National Library of Medicine Classification's larger bulk, and that Bliss gives clear, unambiguous, full and specific subject indexing. The disadvantages of alphabetic subject indexing are mentioned. Finally some defences put forward for the National Library of Medicine Classification are criticized.