stics of the interface. physical address The address of a physical communications device in a system. physical interface The definition of the number of pins in a connector, the number of wires in a cable, and what signal is being carried over which of the pins and over which of the wires, to ensure that the information is being viewed compatibly. picocell A tiny cell architecture in the cellular system that covers about 150 feet (46 m). Com- pared to the microcell design, the picocell design offers even better frequency reuse, even lower power, even smaller subscriber units, and even better, longer battery life. piconet An ad hoc computer network of devices that use Bluetooth protocols to allow a mas- ter device to interconnect with slave devices. (packet Internet groper) The name of a program used with TCP/IP internets to test reachability of destinations by sending them an ICMP echo request and waiting for a reply. pixel (picture element) In computer graphics, the smallest element of a display space that can be independently assigned color and intensity. PKE (public key encryption) A message authentication mechanism that is part of most Web browsers. PKI (public key infrastructure) A process that secures e-business applications such as pri- vate e-mail, purchase orders, and workflow automation. It uses digital certificates and digital sig- natures to authenticate and encrypt messages and a CA to handle the verification process. plant The physical equipment of a telephone network that provides communications services. Glossary plotter plotter A device that converts computer output into drawings on paper or displays the output on display-type terminals instead of printing a listing. PLP (Packet Layer Protocol) A standard in the network layer of X.25. PLT (powerline telecommunications) A wireline technology that provides the transmis- sion of data to users over the same lines that bring electric power to homes and businesses. PLT could allow electrical utilities to provide high-speed Internet, voice, data, and vi