Date of this edition: January 29, 2007
The USA is changing its time zone rules, effective March 1, 2007, as part of the Energy Policy Act of 2005. The change affects when daylight saving time starts and ends:
|Daylight Saving Time:||Old:||New:|
|Starts||The first Sunday in April||The second Sunday in March|
|Ends||The last Sunday in October||The first Sunday in November|
While the standard rule will change across all states, US states will still have the right not to observe daylight saving time, as per the Uniform Time Act of 1966. For information about American time zones, see http://www.time.gov.
Canada is changing its time zones in a similar way; for more information, see http://inms-ienm.nrc-cnrc.gc.ca/time_services/daylight_saving_e.html and http://inms-ienm.nrc-cnrc.gc.ca/faq_time_e.html.
Mexico's rules for daylight saving time remain unchanged. For more information, see http://www.cenam.mx/horaexacta.asp.
In QNX 4, the TZ environment variable specifies the time zone. This variable might be set in the following files:
You need to edit these files and update the setting for TZ.
|If TZ isn't set, it's assumed to be EST5EDT, which the libraries interpret according to the old rule.|
Make sure that wherever you specify the time zone, you use the full specification, which is in the form (with spaces added for clarity):
std offset dst offset, rule
The complete format is as follows:
Its components are:
The hour (0 <= hh <= 24) is required, but the minutes (0 <= mm <= 59) and seconds (0 <= ss <= 59) are optional. If the hour is preceded by a minus sign (-), the time zone is east of the prime meridian; otherwise it's west (which may be indicated by an optional preceding "+").
where the first date describes when the change from standard to summer time occurs, and the second date describes when the change back happens. Each time field describes when, in current local time, the change to the other time is made.
The format of date may be one of the following:
The time has the same format as offset, except that no leading sign ("+" or "-") is allowed. The default, if time is omitted, is 02:00:00.
For example, the rule for Newfoundland time, NST03:30NDT02:30,M3.2.0/00:01,M11.1.0/00:01, indicates the following:
Here are the new definitions of the US and Canadian time zones. A blank in the "As observed in" column indicates the general case.
|Time zone:||As observed in:||Definition:|
|New Brunswick and Labrador||AST04ADT03,M3.2.0/00:01,M11.1.0/00:01|
|Arizona (non-Navajo region)||MST07|
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Published under license by:QNX Software Systems International Corporation
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