There are some things to bear in mind if you need to work with time calculations
and time zones.
-
Some utilities get a list of time zones from
/etc/timezone/uc_tz_t, but we don't guarantee that this
file defines all of the world's time zones or that it's up-to-date; time zones
depend on local legislation and may differ from those given in this file. The
abbreviated names in this file above aren't necessarily standard and might not
uniquely identify the time zone.
- The USA changed its time zone rules, effective March 1, 2007, as part of the Energy
Policy Act of 2005. The change affected 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 changed across all states, US states 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 changed its time zones in a similar way; for more information, see
http://www.nrc-cnrc.gc.ca/eng/services/time/index.html.
- The calculation of local time in QNX Neutrino isn't sophisticated enough to apply the
old rules before March 1, 2007, and the new rules after that. The setting you use
for TZ applies to all local times.
- The library interprets a short time zone specification (e.g.,
EST5EDT) according to the new rules.