Working with Time Zones

A new version of Working with Time Zones has been developed by the Internationalization (I18N) Core Working Group. This update has exceptional value because sometimes human-PC interaction suffers from the misunderstandings connected with differences in time. The purpose of the Core Working Group is to make it easier for the computer applications to understand the differences among the time zones and time formats. It is very important for many modern applications which are used in different time zones, especially if they are portable or can get access to the Internet. In fact different programs interact with each other on different platforms and the current changes simplify the process of harmonization of their interactions within the issue what time and time zone actually is.


Among general requirements for the majority of the modern software is a necessity to operate with time, duration and dates. In many cases it is a big problem for the program developers because these values are subordinated by the timekeeping and calendar rules, which are actually abstruse. One of the most complicated things for the applications is the time zone rule which is sometimes even confusing for the humans.

Observed Time

The timekeeping systems have been originally developed with the help of observable events, such as sunset and sunrise, the moon and sun’s evident position against each other and the other space objects, etc. It has been agreed that these events must be subdivided into certain units, such as hours in a day or minutes in an hour. It makes the timekeeping system simpler.

Incremental Time

But anyway the traditional observed time system is too imperfect especially for the computers and global network. It is not always comfortable to use observed events like sunrise, that’s why the mechanical timekeeping (incremental time) supplanted the traditional system. The main advantage of incremental time is that it can actually predict the observed events in the most cases.

Universal Coordinated Time (UTC) is the basis for modern timekeeping: among other things, it provides a common baseline for converting between incremental and observed time. UTC is also known a GMT (Greenwich Mean Time). There are some subtle differences between the two, but none that affect the average person.

What Is a Time Zone?

A time zone is a range of rules which defines the local time in any certain point of the globe. It is arranged what time zone refers to each local region and it is tied to the observed time anyway.

Before the rules for international time zones have been established, local time of each region was derivative from observations. It is easy to set clock on many events, e.g. on local noon, but the observations will be quite different on very short distances of land. You will only need to move 28 kilometers (17 miles) or even less (depending on your remoteness from the equator) away from the point to observe the local noon has changed by one minute.

Time zones were originated in several countries by railroad operators. Maintaining a schedule for large geographic areas allowed people in the various locations served by the railroad know when the train would arrive (and depart). Coordinating trains could be scheduled between stations (using a single line in alternating directions, for example), avoiding observational error, local customs, and other issues combined with a plethora of local times to make accurate train scheduling of this sort difficult.

Railroads solved this problem by adopting fixed regions in which the same local time was used throughout. These "time zones" were "one hour wide": the local time in the middle of the time zone was used throughout the region, so that the most observational deviation most people would see was about half an hour (and most people experienced a smaller deviation). This is a value small enough that most people won't notice the difference between actual and observed time.

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