Consider the first version of the treaty signing ceremony in which the train was not moving, but instead was at rest in the station. Imagine that you are strolling along the platform watching the ceremony. Those on the train again claim that the presidents signed at the same moment. Will you agree with their assessment?

In the treaty signing ceremony, those on the train say the presidents signed at the same moment while those on the platform say the President of Forwardland signed first and the President of Backwardland signed second. Notwithstanding the difference in these two perspectives, what is the real answer regarding whether or not the presidents signed at the same moment?