| Time keeping database (tkdb)
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IANA time zone database (tzdb)
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| Exactly one term for one kind of object
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- Terms are used interchangeably (region = zone)
- Terms are used ambiguously (zone for IANA zones and real world zones)
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| Smallest geographic unit is named "sector"
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Smallest geographic unit is named "zone"
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| The sectors cover the whole surface of the earth
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Some areas are not covered, e.g. the ISO 3166 country "Bouvet Island"
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| Each sector has exactly one sector ID.
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Some zones have multiple IDs via links. These links can
- represent former IDs of the zone due to spelling change for the reference location
- represent former IDs of the zone due to reference location change (Tel Aviv -> Jerusalem)
- represent IDs of former zones (Vaduz links to Zurich)
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| A sector ID only contains alphanumeric characters, not case sensitive. (Note: further restriction likely)
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A zone ID can contain alphanumeric characters and /-._
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| New sectors are created only by splitting and deprecating old sectors, so a user can know if an assignment of an ID to an object needs a check for correctness.
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- User can link an object to a tzid, but get's no notification if later the object is located in another zone having a different tzid
- Different locations are linked, e.g. Vaduz points to Zurich, Tel Aviv to Jerusalem
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| Relations between deprecated sectors and the sectors that have been created out of them are published.
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No split history is explicitly published.
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| Record all legal time
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- no time for Bouvet Island, while Norwegian government has defined it,
- limited support for pre-1970 data
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| Provide time zone acronyms that are unique within each country and at any given point in time refer to only one offset from a base time
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Uses EST and CST for time stamps of zones in Australia that use DST and those that do not. That means for a given point in time during summer the offset from UTC and therefore UTC itself cannot be derived from the local time representation.
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| ISO 3166-1 alpha-3 codes for countries
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ISO 3166-1 alpha-2 codes for countries. Some of the codes have been re-assigned, e.g. CS can refer to Czechoslovakia or Serbia and Montenegro.
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