What is a library OPAC?

Abstract

PurposeThis paper aims to look at online public access catalogues (OPAC) operations in the light of the philosophy of information, communication theory and semiotics, and to revisit fundamental questions about the nature of library OPACs and the ways in which they function.Design/methodology/approachThis exercise is pursued through examination of the multiple tensions implicit in any cataloguing or indexing system: the competing requirements of organisation and retrieval, description and classification.FindingsThe paper finds that for an OPAC to be practicably usable the potential complexity of the information it contains must be reduced to a manageable level of simplicity. OPACs purport to allow complete retrieval, even though data structures and index definitions are not transparent. They necessarily impose a framework of retrieval that conceals information at the same time as it presents it, and therefore to an extent they undermine the very concept of information literacy. In an online environment catalogues have been able easily to move beyond the scope of individual library collections and to incorporate an increasing range of non‐traditional types of information, thus introducing further tensions between their roles as indexes and as information sources in their own right.Originality/valueThe multiple tensions involved can be conceptualised in terms of indeterminacy of the communication code and indeterminacy of the linguistic sign. A clear theoretically‐based understanding of these issues is essential to ensuring optimal OPAC design.