Each plot that exists at a particular animation frame must use a specific database state so the correct data will be plotted. When VisIt is in keyframing mode, the database state can also be keyframed so you can control the database state used for a plot at any given animation frame. The ability to set an arbitrary database state keyframe for a plot allows you to control the flow of time in novel ways. You can, for example, slow down time, stop time, or even make time flow backwards for a little while.
There are two ways to set database state keyframes in VisIt. The first way is to move the Keyframe time slider to the desired animation frame, enter a new number into the text field next to the Keyframe Window's Add state keyframe button, and the click the Add state keyframe button. As an alternative, you can use the Main Window's Time slider to create a database state keyframe, provided the active time slider is not the Animation time slider. To set a database state keyframe using the Time slider, select a new database time slider from the Active time slider combo box and then change time states using the Time slider. Instead of changing the active state for the plots that use the specified database, VisIt uses the information to create a new database state keyframe for the active animation frame.