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Notes on assigning <tz-hint>s
-----------------------------
The <tz-hint> field in Locations.xml.in is used by the clock applet to
guess the correct time zone that goes with a particular location. As
the tag name suggests, it is just a hint; the user is allowed to
override it if the applet guesses wrong. Still, it is nice to have
them be as close to correct as possible.
The timezone names come from the tzdata database; you should have a
complete list of the current timezones names in
/usr/share/zoneinfo/zone.tab. If you are going to be figuring out the
timezones for a region, it may also be useful to grab the source data
from ftp://elsie.nci.nih.gov/pub/. (The "tzdataXXXXX.tar.gz" file)
The most important thing to realize about tzdata is that it has a
separate time zone name for every region that has had its own distinct
timezone rules *at any point since 1970* (the start of UNIX time_t).
This means that many of the timezones listed are no longer in use and
can mostly be ignored. Eg, zone.tab lists 11 timezones for Argentina,
even though as of 2008 all of Argentina is in the same timezone.
In the cases where tzdata has more timezones for a country than the
government of that country recognizes, Locations.xml.in tries to pick
one tzdata timezone to correspond to each government-defined timezone,
and uses those timezones throughout the country rather than using the
historically-more-specific ones. (This will make it easier to localize
the names of the timezones in the future.) So, eg, in the mainland
United States, the four official timezones (Eastern, Central,
Mountain, and Pacific) are mapped to "America/New_York",
"America/Chicago", "America/Denver", and "America/Los_Angeles",
respectively. Regions that have switched from one timezone to another
in the past (such as parts of Kentucky and Indiana) are simply listed
according to whichever timezone they are *currently* in, rather than
picking an appropriate "micro-timezone" such as
"America/Indiana/Indianapolis".
Finally, the names of timezones will occasionally change between
releases of tzdata. (Eg, "Asia/Calcutta" was recently renamed to
"Asia/Kolkata" to match the new preferred spelling of that city.)
Locations.xml.in should always use the most recent names, because
distros should always be shipping the most recent tzdata, to ensure
that the daylight-savings-time rules for different countries match the
latest government decrees.
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