of six 8x8-pixel blocks of which two contain chrominance information and four contain luminance information components. A macroblock contains 16x16 pixels- worth of Y (luminance) information and the spatially- corresponding 8x8 pixels that contain CB and CR information. Metropolitan Area Network. Megabits per second or approximately one million bits per second. See multipoint conferencing (or control) unit. media Air, water, space and solid objects through which information travels. The information that is carried through all natural media takes the form of waves. Media Access Control MAC. The network protocol that controls access to a LAN's bandwidth and could include techniques that would reserve bandwidth for isochronous communications. megabyte 1,048,576 bytes-220. Megastream British Telecom's brand name for a digital system that offers the customer thirty 64 Kbps channels. Used in high-bandwidth video conferencing systems, whether point-to-point or dial-up (using the ITU-T's HO dialing standard). memory A digital store for computer data that commonly Glossary of Terms consist of integrated circuits. There are two primary types: read-only memory or ROM and random-access memory or RAM. Merged Gateway Control A protocol for controlling media gateways. It is the Protocol combination of Level 3's IPDC and Bellcore's and Cisco's SGCP (Simple Gateway Control Protocol). mesh topology A networking scheme whereby any node can communicate directly with any other node. Modified Final Judgment. The out-of-court settlement that broke up the Bell System, severing the Bell Operating Companies from AT&T. See Merged Gateway Control Protocol. microsegmenting The process of configuring Ethernet and other LANs with a single workstation per segment using hubs and inexpensive wiring. The goal is to remove contention from Ethernet segments to guarantee enough bandwidth for desktop video and multimedia. With each segment having access to a full 10 Mbps of Ethernet bandwidth, users can avail themselves of applications that incorporat