frequency and therefore more resolution lines are available. Super-VHS and Hi8 systems use Y/C video. YCbCr This term refers to the three different components that make up component video. Y represents the luminance portion of the signal. Cb and Cr represent the two different chroma components. CCIR-601 specifies 8- bit encoding for component video. White is luma code 235. Black is luma code 16. A trichromatic color system used in NTSC color television systems. The luminance signal is the Y signal. There are two elements of color, hue and saturation. The color information is modulated onto the subcarrier with the phase of the sine wave describing the color itself and the amplitude describing the level of color saturation. Y uses 4.5 MHz, I uses 1.5 MHz and 1 uses 0.5 MHz. YPbPr Part of the CCIR Rec. 709 HDTV standard that refers to three components (luma and two color components) that are conveyed in three separate channels with identical unity excursions. YPbPr is employed by component analog video equipment such as M-II and Betacam. In YPbPr, Pb equals (0.5/0.886) multiplied by Bgamma minus Y. Pr equals (0.5/0.701) multiplied by Rgamma minus Y. The complete set of component signals, that comprise luminance (Y) and the two color difference signals, U (B-Y) and V (R-Y). Zigzag scanning Used in the Discrete Cosine Transform, zigzag scanning results in the reordering of DCT coefficients from the lowest spatial frequency to the highest. Since Video Communication: the Whole Picture the highest spatial frequencies have values that tend toward zero, reordering them through zigzag scanning results in long strings of zeros that can be abbreviated using run-length encoding. INDEX 1996 Olympics application sharing, 292 telecommuting, 23 applications sharing / document collaboration, 303 3COM, 232 3-D, 307 applications suites, 294 802.14, 216, 217, 441 Asymmetrical Digital Subscriber Line, 389 Aboriginal Asynchronous Transfer Mode (ATM), 13, Tanami Network, 45 absorption loss, 387 failure to provide carrier gateways, 196 ac