andwidth is available for information exchange. This differs from channels in which part of the channel is reserved for signaling, control or framing bits. Compression Labs, Incorporated, San Jose, California is one of the foremost codec manufacturers in the world. CLI was the developer of the first "low- bandwidth" codec in the US, VTS 1.5. This codec was one of the first two codecs (along with one from NEC from Japan) able to compress full-motion video to 1.5 Mbps transmission speeds. client A service-requesting program in a client/server computing environment that solicits support (service/resources) from a server, using a network to convey its request. The client provides the important resources required by a user to interface with a server. The term 'client' has, however, strayed from this strict definition to become a catchall phrase. A client today is often assumed to be a front-end application that offers user-friendly GUI tools for such actions as setting up conferences, adding additional participants, opening applications, copying files, and storing files. clock An oscillator. A PC's CPU clock regulates the execution of instructions. Clocks are also used to create timing reference signals in digital networks and systems for the purpose of synchronization. Central office. A CO can be one of many types of switching systems, either analog or digital, which connect subscriber lines to other lines and network trunks on a circuit-switched basis. The two most common in the US are AT&T's 5ESS and Nortel's DMS-100, both of which are digital. Glossary of Terms coaxial cable A cable with one central conductor surrounded by an insulator that is, in turn, surrounded by a cylindrical outer conductor and covered by an outer insulation sheath. The insulator next to the central conductor is typically polyethylene or air and the outer conductor is typically braided copper. Coaxial cables are used to carry very high-frequency currents with low attenuation; often in cable television networks. codec A sophisticated digital 