s. They might also hear a collision occur when two devices attempt to send information across the same channel at the same time. Channel Service Unit. A customer-provided device, a CSU provides an interface between the customer and the network. The CSU ensures that a digital signal enters a communications channel in a format that is properly shaped into square pulses and precisely timed. It also provides a physical and electrical interface between the data terminal equipment (DTE) and the line. CU-SeeMe A free videoconferencing program (under copyright of Cornell University and its collaborators) available to anyone with a Macintosh or Windows and a connection to the Internet. CU-SeeMe allows a user to set up an Internet-based videoconference with another site anywhere in the world. By using a reflector, multiple parties at different locations can participate in a CU-SeeMe conference, each from his or her own desktop computer. D-channel In an ISDN network the D-channel is a signaling channel over which the carrier passes packet-switched information. The D channel can also support the Video Communication: the Whole Picture transmission of low-speed data or telemetry sent by the subscriber. Digital Tape Component Format. The CCIR 601- approved digital standard for making digital video recordings. It records each component separately and employs the YCbCr coding scheme. Digital Tape Composite Format. A digital system that is considerably less costly than D1. It records a composite signal in an 8-bit digital format that is derived by sampling the video signal at a rate of four times the frequency of the subcarrier. D2-MAC One of two European formats for analog HDTV. Digital-analog converters. DMIF-Application Interface (DAI) is an expression (a protocol message) of the functionality provided by DMIF. The much-misused term that indicates any representation, such as characters or analog quantities, to which meaning is or can be attached or assigned. Data is the plural of datum, which means "given information" or "the b