The timeline is displayed as a blue line in the 3D history [3D History] window. It symbolizes the time at which the currently loaded component was viewed.

View of an example component

The timeline can be moved to a different position in the 3D history [3D History] using drag & drop or ALT + mouse wheel. The invisible steps that were created at a later point in time are grayed out in the history. They are only displayed again as soon as the timeline is moved so that they are above the line.

View with shifted timeline