The ANSI information retrieval scheme protocol (Z39.50) is used for simple plain language text-based database queries. This pre-Internet protocol was originally planned as an electronic card file system for libraries. Server access requires using a Z39.50 client to connect to a database known as a "Target". To access a Target, the Client needs to know the URL with Port number, and the Target name (<server>:<port>/<target path>). The URI that precedes the address is "tcp:". Many Targets held on different Servers also have identical (default) names, due to the fact that many of the databases were originally built on stand-alone systems by library automation companies. Be aware that a Target database can be constructed using any of several formatting schemes, called a "Record Type". The four most popular Record Types are marc21, opac, sutrs, and xml. Below are addresses to various free public access Z39.50 servers.
[IANA Port assignment = 210]