Time, contrary to popular belief and classical physics, is not a constant. Especially not “the time” the watches tell us. It is, after all, a mere convention, put up to help people in everyday life. Historically, noon is defined as the point in time, when the sun is at its highest point the current day. Without travel this definition would sufficient, even though the actual time of noon differs over the year. Linking cities faster than a days travel throws this system into a huge problem of adjusting time on the go. Unfortunately, the solution to this malaise was half backed (and another arbitrary convention), for in the summer months the evenings were too short for an urban lifestyle. The correction to this was yet another convention, but this time not coordinated between all parts of the world, all countries nor all time zones. All this apparently makes time keeping a complicated matter as long as local time is preferred to UTC. For 24/7 operations, every change in time is cruel some and hence best avoided. Thus computers keep time in a single format and adjust the output accordingly. Since most computers are not aware of their location but the implications a certain location has in respect to time (stored in the zoneinfo file), this should be the only necessary input. At least until a country changes its rules (like the US did). Then every zoneinfo (worldwide) has to be updated. So if an unexplainable skew of one hour occurred since last Sunday, chances are high that something went wrong with that update.