The Time Zone Database (often called tz or zoneinfo) contains code
and data that represent the history of local time for many
representative locations around the globe. It is updated periodically
to reflect changes made by political bodies to time zone boundaries,
UTC offsets, and daylight-saving rules.

Historical local time information has been included here to:

* provide a compendium of data about the history of civil time that
  is useful even if not 100% accurate;
* give an idea of the variety of local time rules that have existed
  in the past and thus an idea of the variety that may be expected
  in the future;
* provide a test of the generality of the local time rule description
  system.