In Chariots of the Dogs, the time-traveling elevator is operated using so-called time cards, which encode the time and place to be traveled to. The intended time cards are printed by the computer in the T.H.E.M. spaceship, but Bosco modified a carbon dater into a "time scanner" that creates time cards compatible with the system. These cards always lead to a birthday of the person being scanned; it's unclear how the year is determined.