The csv file containing the zone_specs used by the
boost::local_time::tz_database is intended to be customized by the
library user. When customizing this file (or creating your own) the
file must follow a specific format.
This first line is expected to contain column headings and is therefore
not processed by the tz_database.
Each record (line) must have eleven fields. Some of those fields can
be empty. Every field (even empty ones) must be enclosed in double-quotes.
Ex:
"America/Phoenix" <- string enclosed in quotes
"" <- empty field
Some fields represent a length of time. The format of these fields must be:
"{+|-}hh:mm[:ss]" <- length-of-time format
Where the plus or minus is mandatory and the seconds are optional.
Since some time zones do not use daylight savings it is not always necessary
for every field in a zone_spec to contain a value. All zone_specs must have
at least ID and GMT offset. Zones that use daylight savings must have all
fields filled except: STD ABBR, STD NAME, DST NAME. You should take note
that DST ABBR is mandatory for zones that use daylight savings (see field
descriptions for further details).
********* Fields and their description/details *********
* ID
Contains the identifying string for the zone_spec. Any string will
do as long as it's unique. No two ID's can be the same.
* STD ABBR
* STD NAME
* DST ABBR
* DST NAME
These four are all the names and abbreviations used by the time
zone being described. While any string will do in these fields,
care should be taken. These fields hold the strings that will be
used in the output of many of the local_time classes.
Ex:
time_zone nyc = tz_db.time_zone_from_region("America/New_York");
local_time ny_time(date(2004, Aug, 30), IS_DST, nyc);
cout << ny_time.to_long_string() << endl;
// 2004-Aug-30 00:00:00 Eastern Daylight Time
cout << ny_time.to_short_string() << endl;
// 2004-Aug-30 00:00:00 EDT
NOTE: The exact format/function names may vary - see local_time
documentation for further details.
* GMT offset
This is the number of hours added to utc to get the local time
before any daylight savings adjustments are made. Some examples
are: America/New_York offset -5 hours, & Africa/Cairo offset +2 hours.
The format must follow the length-of-time format described above.
* DST adjustment
The amount of time added to gmt_offset when daylight savings is in
effect. The format must follow the length-of-time format described
above.
#####################################################################
##### TODO: more rule capabilities are needed - this portion of #####
##### the tz_database is incomplete #####
#####################################################################
* DST Start Date rule
This is a specially formatted string that describes the day of year
in which the transition take place. It holds three fields of it's own,
separated by semicolons.
* The first field indicates the "nth" weekday of the month. The
possible values are: 1 (first), 2 (second), 3 (third),
4 (fourth), 5 (fifth), and -1 (last).
* The second field indicates the day-of-week from 0-6 (Sun=0).
* The third field indicates the month from 1-12 (Jan=1).
Examples are: "-1;5;9"="Last Friday of September",
"2;1;3"="Second Monday of March"
* Start time
Start time is the number of hours past midnight, on the day of the
start transition, the transition takes place. More simply put, the
time of day the transition is made (in 24 hours format). The format
must follow the length-of-time format described above with the
exception that it must always be positive.
* DST End date rule
See DST Start date rule. The difference here is this is the day
daylight savings ends (transition to STD).
* End time
Same as Start time.
