OpenHistoricalMap/Tags/Tag/boundary=timezone
 boundary = timezone
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OpenHistoricalMap tag for a standard time zone boundary. 
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| Group: boundaries |
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| Status: in use |
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A time zone is a territory within which certain timekeeping rules apply. In the late 19th and early 20th centuries, most countries legally codified standard time zones. Some correspond to administrative boundaries per se (boundary=administrative), while others are defined in terms of natural, artificial, and theoretical linear features, just like other kinds of boundaries. A time zone is known by a name and generally associated with an offset from GMT or UTC. Some timekeeping rules, such as daylight saving time, do not necessarily apply uniformly within the time zone.
Unlike in OpenStreetMap, time zone boundary relations in OHM correspond one-for-one with legally defined boundaries, independently of daylight saving time or other deviations from standard time. Two adjacent time zones may observe the same time during part of the year or year-round. Boundary adjustments are modeled as overlapping boundary relations corresponding to the resulting time zone, as opposed to the tz database convention of smaller boundaries corresponding to the adjusted region.
How to map
Create a relation and add the type=boundary boundary=timezone tags to it. See Relation:boundary for more information on how to map a boundary.
Tags to use in combination
name=*– the usual or official name of the time zone (e.g., Pacific Time Zone)utc=*– Coordinated Universal Time offset of the time zone in ±hh:mm format (e.g.,utc=-07:00for Mountain Time Zone, even though most of this time zone observes UTC−6 during the summer)start_date=*– the day on which the time zone was established or modifiedstart_date:edtf=*– the time at which any changeover took place (e.g.,start_date:edtf=2007-11-04T02:00-05:00)