Using the Z39.50 Information Retrieval Protocol in the Internet Environment

Z39.50 is a US national standard defining a protocol for computerto-computer information retrieval that was first adopted in 1988 [1] and extensively revised in 1992 [2]. It was developed by the National Information Standards Organization (NISO), an ANSI-accredited standards development body that serves the publishing, library, and information services communities. The closely related international standard, ISO 10162 (service definition) [3] and 10163 (protocol) [4], colloquially known as Search and Retrieve or SR, reached full International Standard (IS) status in 1991. Work is ongoing within ISO Technical Committee 46 Working Group 4 Subgroup 4 to progress various extensions to SR through the international standards process. The international standard is essentially a compatible subset of the current US Z39.50-1992 standard. Z39.50 is an applications layer protocol within the OSI reference model, which assumes the presence of lower-level OSI services (in particular, the presentation layer [5]) and of the OSI Association Control Service Element (ACSE) [6] within the application layer.