As time flows, the data move from the bottom to the top. This is used when you wish to fix the data at a specific time and compare them with other data. Click the right button of the mouse on the data you wish to fix and click the menu of Add to Fixed State. Then the data will be fixed at the uppermost step. Once fixed, the data remain at the position even if the step goes beyond the screen as time elapses. The number of data that can be fixed is as many as that of steps displayable on the screen.