Z39.50 Access to California Public and Other Libraries

The Z39.50 Information Retrieval Protocol (Z39.50/ISO 23950), is a computer protocol that defines a standard way for two computers to communicate for the purpose of information retrieval. A Z39.50 implementation enables one interface to access multiple library catalogs providing the end-user with nearly transparent access to other systems.

The protocol specifies formats and procedures governing the exchange of messages between a client and server enabling the client to request that the server search a database and identify records which meet specified criteria, and to retrieve some or all of the identified records.

Individuals may use Z39.50 with standalone client software which is available in both commercial and open source versions, or may use a web-based gateway that still uses Z39.50 but accepts input and presents record output in a web browser.

Access information for the California State Library catalog, University of California MELVYL catalog and the Library of Congress catalog is listed below:

Host IP Port Database Name
California State Library catalog.library.ca.gov 9991 CSL01PUB
MELVYL melvyl.cdlib.org 210 CDL90
Library of Congress z3950.loc.gov 7090 Voyager
(Books database)

Some software products for retrieving and managing bibliographies utilize Z39.50 to connect to library catalogs. If the library's catalog configuration information is not already available on the vendor's website the Z39.50 configuration information can be used to establish a custom setup.