the effect of a motion sequence. Annex A (To Recommendation H.261). Inverse Transform Accuracy specification that defines the maximum tolerable error thresholds for the DCT. Annex B (To Recommendation H.261). Sets forth a Hypothetical Reference Decoder. Annex C (To Recommendation H.261). Specifies the method by which the video encoder and decoder delays are established for a particular H.261 implementation. The American National Standards Institute. A non- governmental industry organization that develops and publishes voluntary standards for the US ANSI has published standards for out-of-band signaling, for voice compression, for network performance, and for various electrical and network interfaces. antenna An aerial or other device that collects and radiates electromagnetic energy. Application Programmer Interface A set of formalized software calls and routines, which can be referenced by an application program to access underlying network or other services. application An application is software that performs a particular useful function for a user-e.g., a spreadsheet tool, a word processing facility. Examples include word processing, spreadsheets, distance learning, document conferencing, and telemedicine. application sharing A collaborative conferencing feature that provides personal conference participants with read/write access to an application, even when one or more of these participants does not have the application Video Communication: the Whole Picture running at their desktop. In application sharing, one user launches and controls the application. application viewing In personal conferencing, the ability of one system to screen-slave off another system. Every keystroke or mouse movement made by the user who runs the application can be seen by the user at the other end, even though he/she is not running the application and has no control over it. architecture The design guidelines, physical and conceptual organization, and principles that describe how a system or network will support an activity. Arch