Reviews the 20 years' evolution and development of the Universal Standard Bibliographic Code (USBC), as a means of overcoming the weaknesses inher ent in the International Standard Book Number (ISBN), from its first proposal in 1974. Briefly describes the various phases of USBC's development, includ ing : first extensive testing (1977-1979); first research project (1980-1982); work performed on USBC as part of proposals for the setting up of the United Kingdom Library Database System (UKLDS) (1982-1984), in which USBC was to be used to create a merged retrospective database of MARC and non MARC cataloguing records; the DOCMATCH Projects, using the USBC with periodical articles (1987-1989); refining of USBC by means of expert systems (1986-1987); use of USBC to clean up the BLCMP database (1989-1991); and the QUALCAT Project, to set up a large bibliographic database integrating records from different databases and using USBC for merging, cleaning and control and to develop an expert system to select the best record from a num ber of duplicates (1989-1991). Reports briefly on the project, undertaken by Bradford University, Department of Computing, UK, to explore the application of USBC technology to the British Library Document Supply Centre's com puterized interloans system. Concludes that, although the USBC has never achieved the status of an accepted standard, it has more than made up for this by demonstrating its adaptability and power in a range of situations requir ing an ability to detect duplicate records and to merge and combine files.