research. Such projects have included communities such as the Society of American Archivists, the Open Archives Initiative, the Institute for Museum and Library Services, the International Organization for Standardization, the National Information Standards Organization, the World Wide Web Consortium, the Internet Engineering Task Force, and Internet2. One of the most successful contributions to this effort was the Dublin Core Metadata Initiative, "an open forum of libraries, archives, museums, technology organizations, and software companies who work together to develop interoperable online metadata standards that support a broad range of purposes and business models." OCLC has collaborated with the Wikimedia Foundation and the Wikimedia volunteer community, through integrating library metadata with Wikimedia projects, hosting a Wikipedian in residence, and doing a national training program through WebJunction called "Wikipedia + Libraries: Better Together". Online database: WorldCat OCLC's WorldCat database is used by the general public and by librarians for cataloging and research. WorldCat is available to the public for searching via a subscription web-based service called FirstSearch, to which many libraries subscribe, as well as through the publicly available WorldCat.org. Identifiers and linked data OCLC assigns a unique control number (referred to as an "OCN" for "OCLC Control Number") to each new bibliographic record in WorldCat. Numbers are assigned serially, and in mid-2013 over a billion OCNs had been created. In September 2013, the OCLC declared these numbers to be in the public domain, removing a perceived barrier to widespread use of OCNs outside OCLC itself. The control numbers link WorldCat's records to local library system records by providing a common reference key for a record across libraries. OCNs are particularly useful as identifiers for books and other bibliographic materials that do not have ISBNs (e.g., books published before 1970). OCNs are often used as identifiers for Wikipedia and Wikidata. In October 2013, it was reported that out of 29,673 instances of book infoboxes in Wikipedia, "there were 23,304 ISBNs and 15,226 OCNs", and regarding Wikidata: "of around 14 million Wikidata items, 28,741 were books. 5403 Wikidata items have an ISBN associated with them, and 12,262 have OCNs." OCLC also runs the Virtual International Authority File (VIAF), an international name authority file, with oversight from the VIAF Council composed of representatives of institutions that contribute data to VIAF. VIAF numbers are broadly used as standard identifiers, including in Wikipedia. Company acquisitions OCLC acquired NetLibrary, a provider of electronic books and textbooks, in 2002