This paper discusses the construction of the infrastructure for libraries' digital document telecommunications. The first section describes the topologies of the library LAN (Local Area Network) cabling system, including the main characteristics of the LAN and three classical topologies typically used with LANs, i.e., the bus, star, and ring topologies. The second section addresses using the PDS) Premises Distributing System for libraries' LAN cabling work, including the working area, horizontal, management, backbone, equipment, and entrance facility subsystems. The third section covers the transmission media (cable) for libraries' electronic document transportation, including unshielded twisted-pair cable, shielded twisted-pair cable, fiber optics, and coaxial cable. The fourth section suggests the distribution of outlets for library electronic document transportation in accordance with the following library functions or areas: electronic bibliographic service work; reading/reference service area; closed stack rooms of books, periodicals, and newspapers; technical services department; the service area of audiovisual and multimedia materials; office automation; and the fire and security alarm. (MES)