The crossing is not a free parameter. The horizontal meets the diagonal at the home city, and New Orleans is 4th of 15 west-to-east, so it lands at 21.4%. Reversing the diagonal puts the same intersection at 78.6%. Both numbers describe one point. Events are invented; the city roster is real. Vertical offset on an event is collision avoidance and carries no data — duration is a quantity of time, so it reads as bar length on the time axis.