The Chronos Time Zone Repository

The Chronos Time Zone Repository contains the rulesets for all 400+ time zones as defined in the Olson Timezone Database. Each time zone is uniquely identified by a well-known key.

The time zone rulesets specify both the current, historical--and if presently known, also the future--annual recurrence rules for offset/abbreviation transitions for each time zone. The rule model is competent to handle any number of offset/abbreviation transitions during a year, and any number of different annual recurrence rules accross different years. It can also express annual recurrence rules using calendars other than the Gregorian--not even the Olson rule model handles that.

A time zone ruleset may also specify the geographical coordinates of the time zone, provided that the described zone is associated with a particular nominal location (most of them are.) For about 75 of the most commonly used time zones, the ruleset also specifies the time zone's default English name. The mappings from any formerly-used but deprecated time zone keys to the current canonical time zone key are also specified.

The Chronos Time Zone Repository is provided as an archive (.zip) file, whose contents may be either 1) a hierarchical directory structure where each time zone rule set is in a separate file, or alternatively 2) a single 6.7-megabyte XML file.

In the case of the one-file-per-time-zone version, each time zone ruleset is contained in a separate text file whose format is proprietary to the Chronos Date/Time Library (and it's not XML.) In the case of the version containing the single XML-encoded file, each time zone ruleset is a sub-element in the XML file, and the structure/syntax of the XML file is governed by a fully-annotated XSD (see below.)

Although the XML-encoded version is generated by the Chronos Date/Time Library, Chronos does not make any use of it. The XML-encoded version is intended for consumption by other applications and/or date/time libraries. The non-XML version is intended for the use of the Chronos Date/Time Library itself (although there is no restriction on its use by other applications or libraries.)

Current Version: 2009d

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[Chronos] All code (classes and methods, and all associated documentation,) distributed as part of the Chronos Date/Time library are © Copyright 2005-2006 by Alan L. Lovejoy.  All Rights Reserved. Usage is controlled by the Chronos License (which is included in the distribution as the contents of the file {chronos-license.txt}, and is also available from the Chronos web site {})

"Do not go gentle into that good night,
Old age should burn and rave at the close of the day;
Rage, rage at the dying of the light!" -- Dylan Thomas