Network World, 5/19/97

Chair-control video switching: A video-switching method in which a participant at a conference site selects who will be the current broadcaster from the controls provided by the conferencing system. The conference must be using voice-activated video switching, and the H.243 Chair Control option must be installed at the site. Contrast with user-selected video switching.

Continuous presence: Describes an optional conference view where participants view other sites in one of four windows displayed simultaneously - think ''Hollywood Squares.'' Some systems permit video switching among the participants when conferences exceed five video sources.

Director, chair or conference producer: The person who controls the video switching and other activities for all sites participating in a multipoint conference.

Director-selected video switching: A video-switching method in which the conference director selects the video source visible to all participating sites.

End point: a PC or proprietary platform with network interfaces, cameras, microphones, speakers and display capabilities that enable videoconferencing.

Lecturer, presentation or instructional mode: a choice for a site participating in a continuous presence conference in which one site is defined as the broadcaster to all other sites. The speaker or broadcaster is the only participant who sees a mix of other sites. All others view the speaker in maximum window size.

Roll call: the ability for a conference director to cause the conference server to switch to each participant in order to introduce them or to screen the conference for security purposes.

Subconferencing: a multipoint conference mode in which a conference operator has the ability to transfer participants into and out of separate, confidential conferences associated with a meeting, without having participants disconnect and reconnect again.

Single-number dialing: a conference setup feature in which participants who always meet on the same bridge always dial the same number for a predetermined meeting configuration. This dialing option does not dictate whether the meeting includes a conference operator or attendant and is distinct from single-number conference.

Single-number conference: a conference to which all participants dial in with the same number to connect, regardless of their location, and are placed directly into a conference. The conference server exchanges information with the terminal and assigns a free port in the conference on a first come, first serve basis until all the ports in the conference or in the MCU are taken.

User-selected video switching: video-switching method in which a conference site chooses itself as the current broadcaster. The multipoint conference server must be set to voice-activated video switching. Contrast with director-selected video switching.