To label markers:

1. Select Label from the Label pane.
2. Select the marker to be re-labelled from the Marker list or the Viewer window.

   You can also use the Add and Remove buttons at the bottom of the Marker list to add or remove markers.

3. In the Viewer window, click the asterisk (unused segment) to be labelled.

   The segment appears in the Optical editor. You may have to scroll the Timeline indicator if the segment that you are looking for is presently occluded.

4. Drag the Timeline indicator in the Optical editor to find which asterisk should be selected for the next segment. The combination of the Label Helper and Rigid bodies proposes the best segment.