An Evaluation of, and Improvement on, Ayers' Universal Standard Book Number

Ayers’ recent suggestions for a Universal Standard Book Number, logically generated from a catalogue entry, and therefore applicable restrospectively to bibliographic files, have been implemented and tested on two one‐year cumulations of BNB MARC files. The proportion of unique entries provided by the USBN was found to be about 91%. Revisions to the coding tables were made on the basis of a detailed analysis of the results and of determinations of the frequencies of characters in the data elements used. These resulted in improvements to the method, giving an increase in the proportion of unique entries to approximately 96%.