About one-third of the major North American research libraries have chosen to replace old hierarchical systems with new client/server systems. With eleven ARL or equivalent library customers each, Ameritech's Horizon and Endeavor's Voyager, both client server products, are currently the front-runners in this segment of the library systems market. (Horizon's latest major contract was Iowa State University; Endeavor's latest was Purdue.) SIRSI, with ten ARL or equivalent library customers is close behind. DRA already has five customers for its new TAOS client/server product and VTLS has two for its Virtua product. Ex Libris, the Israeli vendor with a US subsidiary, has announced that it is completing negotiations with Notre Dame for its Aleph 500 Client/server system.
The three most numerous hierarchical systems in major North American research libraries are Innovative's INNOPAC (29), Ameritech's NOTIS (20), and DRA's Classic (10).
The other 20+ ARL or equivalent libraries have systems from a variety of other vendors as well as home-grown systems. Clearly, no one system has a lock on this niche.