 connection between a switching point (or in the CATV world, a head-end) and a device or subscriber. store-and-forward Systems in which messages (including video-enabled messages) are stored at an intermediate point for later retrieval. streaking In video, shifting brightness across an image at the vertical location of a bright object. streaming data Any transmission with a time component, such as video and audio signals. Study Group Groups of subject experts that are appointed by the ITU-T, an international standards-setting body that is part of the United Nations. Study Groups draw up Recommendations that are submitted to the ITU-T at the next plenary assembly for adoption. subcarrier A band of frequencies superimposed onto a main carrier frequency. In color television the color information is carried on the same subcarrier as the luminance signal by modulating it onto the upper frequencies of the luma waveform. subjective evaluation During the process of comparing videoconferencing systems, the portion of the comparison that is in the eye-of-the-beholder as opposed to being quantifiable. subscriber A customer of a carrier, service provider or utility. subtractive color Color information that results from reflection or refraction of light. Reflected wavelengths correspond to the colors that people attribute to those objects. The subtractive primaries are magenta, cyan, and yellow. In contrast, additive color results from wavelengths of radiation emitted by light sources. Additive primaries are red, blue and green (RGB). Super CIF A video format defined in the 1992 Annex IV amendment of the ITU-T's H.261 coding standard. Also known as 4CIF in the ITU-T's H.263 standard, it Video Communication: the Whole Picture is comprised of 704 by 576 pixels. super trunks Large diameter coaxial or fiber-optic cables used to carry a signal from a head-end to various hub sites in a CATV network. Super VGA SVGA. A higher resolution version of the VGA standard that allows applications to use video resolutions of 1,024-by-768 pixe