The timetable that a user interacts with. When a user runs an application such as Enterprise Timetabler, the image is loaded into memory on their workstation. The image is downloaded from the server, or loaded from the workstation's hard disk. The user changes data in their image, then uses the writeback function to send the changed data to the SDB. The user can save the image to their workstation's hard disk. Other users might also send their changes to the SDB; a user can use the refresh function to apply those changes to their image.