Distribution Technology refers to the technology used to distribute or deliver the stored encoded document from one point to another. Some form of delivery service may be used (3.5.2), or, if the medium is paper, it may be distributed using point-to-point or distributed FAX (3.5.3). On the other hand, if the medium is digital electronic, then either the document may be converted to paper, by "printing-on-demand" (3.5.4) and subsequently distributed using delivery services or FAX, or data networks (3.5.5) may be used for distribution to a computer workstation (3.6.2), possibly to be converted to another medium, such as paper, at the point of delivery (see 3.6.1).
The Distribution Medium is the medium used to transport the stored encoded document to the presentation or viewing device (3.6.2). The same media that can be used for original documents (1.1) can also be used as distribution media.
Whichever technology is used for storage (3.3.1), digital technologies may usually be used as the medium of distribution, as contrasted with using delivery services (3.5.2) to deliver the document. Paper, for example, can be scanned and transmitted by FAX (3.5.3) or across data networks (3.5.5). The only exception to this at this time is video, which is normally distributed by analog electronic distribution networks (as opposed to digital--see 1.1.6), because of the high information capacity (bandwidth) required. As the bandwidth of data networks grows, however, it is anticipated by many technologists that analog transmission will yield to digital transmission even for video recordings. Films, too, are often transmitted by converting them to video recordings (with some loss of quality at this time), and transmitting them across analog video networks.
Messenger Services refers to the use of local, regional, or national messengering or mail services to hand-deliver documents from the point of inventory or storage to the patron or consumer. One special case of this includes the patrons performing the messengering services for themselves by viewing the document, or by directly acquiring it (purchasing or borrowing), at or from the location of the document's storage.
FAX or Facsimile Transmission is a system of communication or delivery for paper documents or other graphics material in which a special digital image scanner (3.2.3) scans the pages of the document, compresses the scanned image using CCITT Group Compression (18.104.22.168.1), and transmits the digital signals by wire or radio to a FAX receiver at a remote point. The FAX receiver decompresses the signals received and prints the digital image on paper. FAX transmission is a point-to-point protocol that is normally conducted over voice (3.5.6) or data (3.5.5) networks. Usually, scanning and printing devices are relatively slow (about 5 pages per minute), and the quality is limited. The popularity of FAX rests on its simplicity of use and the relatively low cost of the equipment. With the rapid growth of installed FAX equipment, FAX has recently been extensively used for inter-library loan purposes, and is also becoming used for intra- campus delivery purposes.
Print-on-Demand refers to the capability to print documents right at the time they are required by patrons and consumers, rather than following traditional norms of printing documents in advance of need and coping with the need to distribute and inventory printed documents in anticipation of demand. This approach to distribution mirrors the "just-in-time" approach to inventory control. Print-on-Demand techniques are normally used in conjunction with digitally stored documents (22.214.171.124) and data networks (3.5.5). The approach offers the promise of closing the gap between the world of digital technologies and those who maintain the superiority or simply prefer the characteristics of paper documents. Documents may be printed right in the patron's office or at a shared local facility from where it is delivered to or picked up by the patron.
A Data Network is a communications network that transports data between and among computers and computer workstations (network nodes). Such networks may depend upon different physical media to transport the encoded digital signals (twisted pair copper wire, coaxial cable, fiber optic cable, satellite, and so forth); different protocols to encode the signals; and different ways in which the encoded signals are interpreted for use in applications. They also include bridges, routers, and gateways for connecting different media and for translating one protocol into another. Data networks vary considerably in speed and capacity, depending upon the physical media, the protocols used, and the particular architecture of the network. Network speeds and other performance characteristics appear to be more than doubling every two to three years.
Local Area Network (LAN) is a data network used to connect nodes that are geographically close, usually within the same building. In a wider view of a local area network, multiple local area networks are interconnected in a geographically compact area (such as a university campus), usually by attaching the LANs to a higher-speed local backbone.
A Wide Area Network (WAN) is a data network connecting large numbers of nodes and LANs that are geographically remote, such as within a broad metropolitan area, or between widely-separated metropolitan areas. This would also include regional networks, such as NYSERNet, which interconnects research and educational institutions in New York State.
A WAN, or a federation of interconnected WANs, that span the nation, such as the NSFNet, BlTNet, CSNet, CREN, and, more generally, the Internet and the anticipated NREN (National Research and Educational Network). These national networks often use a high-speed spanning national backbone to interconnect regional WANs. Protocols are established to facilitate routing of information across the national networks to users at connected nodes. The national networks often have international connections and outreach.
Voice Networks are local, national, or international networks used to carry voice or telephone traffic. They may be either analog or digital (see 1.1.6). Because of different technical requirements, the transmission of data and voice usually is conducted using different transmission protocols, although it is increasingly common to share the same wiring plant. In general, there is increasing integration between the voice and data milieus.
Cable Networks are local, regional, or national networks normally used for the transmission of analog (see 1.1.6) signals such as video (see 1.1.3) television signals.