Information Retrieval Service Definition and Protocol Specification for Library Applications, officially known as ANSI/NISO Z39.50-1992, and ANSI/NISO Z39.50-1995. This standard, used by WAIS, specifies an OSIapplication layer service to allow an application on one computer to query a database on another. Z39.50 is used in libraries and for searching some databases on the Internet. The US {Library of Congress (http://lcweb.loc.gov/z3950/agency/)} is the official maintanence agency for Z39.50. Index Data, a Danish company, have released a lot of Z39.50 code. Their website explains the relevant ISOstandards and how they are amicably converging in Z39.50 version 4.0. Overview . {Z39.50 resources (http://lamp.cs.utas.edu.au/net.html#Z3950)}. (1996-07-22)