The union catalog contains bibliographic records of holdings from all RLG's 160 member libraries, some of them among the largest. Currently, the collection of records from libraries, archives, and museums includes over 130 million holdings for some 42 million titles. RLG expects to make the file available to the public free through most of 2004, while it develops and implements a business model.

Created over the course of 23 years, the massive union catalog covers books, serials, maps, films, recordings, archives, manuscripts, computer files, and more, from 300 countries in over 370 languages. RedLightGreen went live on Sept. 22 when word went out to four of RLG's 160 member institutions. Records connect to library holdings and even supply local call numbers. RLG began the project of bringing the catalog to the Web in 2002 using an Andrew W. Mellon Foundation grant.

Previously, the catalog had only been available to subscribing institutions through several interfaces, such as a Eureka interface, telnet access to RLIN (RLG's own network), and a Z39.50 gateway. These connections remain available. Merrilee Proffitt, RLG program officer, described the traditional interfaces as targeting a different market with different features and functionality. For example, the traditional RLG Union Catalog services have expanded searching and sorting and will display all library holdings connected to a record. RLG also charges for these services. Proffitt did not see RedLightGreen as threatening revenue from the other outlets. When RLG starts to develop a business model for RedLightGreen next spring, Proffitt hopes that it can find new sources of revenue, including sponsorships.

Besides serving to locate valuable resources and verify citations, RedLightGreen also provides links beyond those of traditional catalogs and can even output citations in different standard bibliographic formats, i.e., APA, MLA, Turabian, and Chicago. Users can also e-mail results, purchase books or CD-ROMs, locate the nearest library owning the title, and even find online versions in some cases.

Built for XML, the records use an adapted version of the Functional Requirements for Bibliographic Records established by the International Federation of Library Associations (IFLA) and the Library of Congress. RLG runs the service using Recommind, Inc.'s MindServer technology to supply accelerated keyword searches, relevance ranking of results, and expanding searches to related categories.

Designed around the needs and habits of undergraduate students, the RedLightGreen interface offers the standard single search box common to Web search engines, but supplemented by an advanced search mode that lets users limit searches to language or one of seven fields. According to Proffitt, RLG plans to wait and see how usage goes before developing more sophisticated search features, such as the ability to limit searches to more than one field at a time. A point-and-click feature in the results display helps users to narrow searches by subject, author, language, etc. Users can even set an automatic filter (cookie) identifying the libraries whose collections most interest them. The service even performs Google searches for book titles and scans a major public domain database collection for fiction titles.

RLG has a loyal following, but nonetheless, it still plays Apple to OCLC's Microsoft. The launch of RedLightGreen would seem to challenge OCLC to rise to a new standard of service for users everywhere. OCLC has long held its own WorldCat union catalog in tight control, making it available to and through libraries, not directly to library patrons. However, over the last couple of years, OCLC has begun experimenting with alternative modes, primarily by linking as a back-up service to online booksellers, such as ABE Books, Bookpage.com, and Alibris for Libraries.

Commenting on the RedLightGreen service, Chip Nilges, director of WorldCat Services' Cooperative Discovery Services, said OCLC Online Computer Library Center, Inc. saluted the effort. "The RedLightGreen project is an impressive response to Web user expectations in simplifying library resource discovery on the Internet. OCLC and our member libraries have been exploring the concept of ‘weaving libraries into the Web' since early 2000. We continue to explore other WorldCat linking opportunities to increase the visibility of libraries on the Web with input and advice from the OCLC Members Council, a variety of advisory groups, library professionals, library patrons, and focus groups."

Library users—and potential library users—everywhere should take advantage of any such new services. Proffitt did not, however, expect that librarians would stop running their own OPACs (Online Public Access Catalogs), if only because of all the inventory and back-office tasks those services perform. Proffitt also felt that libraries would "always want to have their own storefronts branded in their own names" on the Web to serve local constituencies. Nonetheless, the opening up of library holdings to the world might, in time, change some librarians' definition of constituencies.