A variety of hypermedia materials are becoming available and these collections are often served from a library rather than dedicated machines in classrooms. The Perseus hypermedia corpus (2.0) includes about 200 plays, books, poems, and text fragments in Greek and English translation; almost 25,000 24-bit color images of vases, sculpture, coins, and sites; maps; site plans; and a variety of search, navigation, and display tools. [6, 20]. Hundreds of colleges and scores of high schools are currently using Perseus to support instruction in Greek language, ancient history, Greek literature, religion, archaeology, and art history. In many sites, Perseus is delivered through a campus network. In some sites, Perseus is provided on a stand-alone machine in a library. The many CD-ROM corpuses now available for specialized topics challenge schools and individuals to be judicious in acquisition and use of these materials, thus increasing the need for resource sharing functions of libraries.
Another instance of an emerging corpus of material entering digital libraries is the PC-library  a product developed by a publishing consortium. Originally designed for stand-alone PC applications it has now migrated to client/server architecture. At the time of writing some 40 substantial reference volumes including a 10-volume encyclopedia ("Meyer A-Z"), dictionaries for most European languages ("Langenscheidt dictionaries"), the famous German-English "Oxford Duden," and standard scientific reference books on medicine, computer science and CAD are either available or in preparation, some of them containing high quality diagrams and pictures. There are a number of aspects of the PC library particularly worth mentioning: First, an arbitrary subset of the books in the library can be "activated" at any time, and all searches (including fuzzy full text) are carried out only within the books activated. Second, the PC library is not just a set of static books but can be used in a variety of not-only-read mode: persons can leave comments (for themselves or for others); searches can be activated from other applications and the results used in such other applications; books can be augmented by additional (personal) entries, including multimedia material ( e.g. personal pictures or video clips); and material is automatically hyperlinked using a keyword based technique.
As vendors develop new products and as these specialized corpuses become available through global networks, libraries should take responsibility for ensuring secure and legal usage by students and teachers. One example of how libraries and computing centers cooperate today is in negotiating site licenses for these products and maintaining firewall services to ensure that licensing agreements are met. These collaborations can only grow as acquisition, organization, and dissemination of specialized software and hypermedia corpuses increase.Back one topic. See Table 1 Back to Outline.