The DDC Relative Index

The “Relative Index” of the Dewey Decimal Classification (DDC) is investigated over the span of its lifetime in 22 editions of the DDC as to its character as a concept indexing system, its provision of conceptual contexts for the terms it lists, and the way in which the index intersects with special tables of categories used in the system. Striking features of the index that are discussed include how the locater function of an index is expressed in it, its practice of including concepts that have not been given specific notational locations in the system, its two methods of providing conceptual contexts for indexed terms (by means of the notation of the system and by the insertion of enhancement terms that portray conceptual context), and how the index has intersected with three types of special tables of categories in the system. Critical issues raised include the indexing of constructed or synthesized complex concepts, inconsistencies in how enhancement terms are portrayed and the absence of them in some instances, the problem of equating conceptual context with disciplinary context, and problems associated with not in-dexing one type of special table. Summary and conclusions are extended to problems that arise in studying the index