The NISO Standards Committee that originally created and wrote the first version of Z39.50 was disbanded after the standard was approved in 1988. In 1990, a group of Z39.50 implementors formed the Z39.50 Implementors Group (ZIG). This voluntary group of implementors meet in open sessions approximately three times a year to discuss implementation issues, bring requirements for changes to the standard, work out the detailed specifications, and come to agreements that will go into the draft standard. The ZIG uses a public electronic discussion list (instructions to subscribe to the listserv are described below) to discuss implementation and standards development issues between meetings.
When the draft standard is completed, it is NISO's responsibility to assure that ANSI procedures for balloting, consensus, due process, and other requirements are followed, and that the final approved American National Standard is available for use.
Working closely with the ZIG and providing continuity for Z39.50 development is the Z39.50 Maintenance Agency. In 1988 NISO assigned the Network Development and MARC Standards Office at the Library of Congress to be the Maintenance Agency for Z39.50. The Maintenance Agency provides technical coordination of Z39.50 development, registration of implementors, the registration of objects such as attribute sets and record syntaxes used by the standard, and editorial work on the standard. The Maintenance Agency has provided publicly available electronic drafts of Version 3 (address information for access to the drafts is given below); this electronic access to the drafts has broadened participation in revising the standard.