A chronograph is a watch that, in addition to indicating the time of day, also allows the user to time events. The timing can be indicated by the seconds hand and/or additional dials. There are usually two separate pushbuttons, one to start and stop the timing, and the other to reset the hands and/or dials. There are many variations on the chronograph. Some operate with a center seconds hand which keeps time on the watch's main dial. Others use sub-dials to time elapsed hours, minutes and seconds. Still others show elapsed time on a digital display on the watch face. Some chronographs can be used as a lap timer (see "flyback hand" and "split seconds hand"). The accuracy of the stopwatch function will commonly vary from 1/5th second to 1/100th second depending on the chronograph.