creen and fired from a "gun" to create images. Deflecting it from magnetic coils or plates SO that it hits a precise location on the screen focuses the beam. Glossary of Terms electrons Negatively charged particles that, along with positively charged protons, allow atoms to achieve a neutral charge. encoding The process through which media content is transformed for the purposes of digital transmission. encryption The conversion, through the application of an algorithm, of an original signal into a coded signal in order to secure it from unauthorized access. Typically the process involves the use of "keys" that can unlock the code. The most common encryption standard in the US Bureau of Standard's is the DES (data encryption standard) which enciphers and deciphers data using a 64-bit key specified in the Federal Information Processing Standard Publication 46, published in January, 1977. enhanced standard Standards enhancement is a common practice of videoconferencing codec manufacturers. They begin with an algorithm that is compliant with a formal standard (typically the ITU-T's H.320 algorithm). However, they add capabilities that are transparent to dissimilar products that run the standard, but which improve implementation when operating exclusively in their proprietary environment. entrance facilities In a premise distribution system, entrance facilities are the point of interconnection between a building wiring system and a telecommunications network outside the building. entropy A measure of the information contained in any exchange. Entropy is the goal of nearly every compression technique. If information is duplicated, the excess amount (that portion that is over and above what is necessary to convey) is redundant. The goal is to remove the redundant portion of whatever is being conveyed (for our purposes, motion, video, audio, text, and still images). The remainder is entropy-information. envelope The variations of the peaks of the carrier that contain the video signal information. envelope delay The char