NAME [Toc] [Back]
tztab - time zone adjustment table for date(1) and ctime(3C)
DESCRIPTION [Toc] [Back]
The tztab file describes the differences between Coordinated Universal
Time (UTC) and local time. Several local areas can be represented
simultaneously with historical detail.
The file tztab consists of one or more time zone adjustment entries.
The first line of the entry contains a unique string that may match
the value of the TZ string in the user's environment. The format is
tznamediffdstzname where tzname is the time zone name or abbreviation,
diff is the difference in hours from UTC, and dstzname is the name or
abbreviation of the "Daylight Savings" time zone. Fractional values
of diff are expressed in minutes preceded by a colon. Each such
string will start with an alphabetic character.
The second and subsequent lines of each entry details the time zone
adjustments for that time zone. The lines contain seven fields each.
The first six fields specify the first minute in which the time zone
adjustment, specified in the seventh field, applies. The fields are
separated by spaces or tabs. The first six are integer patterns that
specify the minute (0-59), hour (0-23), day of the month (1-31), month
of the year (1-12), year (1970-2038), and day of the week (0-6, with
0=Sunday). The minute, hour, and month of the year must contain a
number in the (respective) range indicated above. The day of the
month, year, and day of the week can contain a number as above or two
numbers separated by a minus (indicating an inclusive range). Either
the day of the month or the day of the week field must be a range, the
other must be simple number.
The seventh field is a string that describes the time zone adjustment
in its simplest form: tznamediff where tzname is an alphabetic string
giving the time zone name or abbreviation, and diff is the difference
in hours from UTC. tzname must match either the tzname field or the
dstzname field in the first line of the time zone adjustment entry.
Any fractional diff is shown in minutes.
Comments begin with a # in the first column, and include all
characters up to a new-line. Comments are ignored.
If the value of the TZ string does not match any line in the table, it
is interpreted according to the current U.S. pattern.
EXTERNAL INFLUENCES [Toc] [Back]
International Code Set Support
Single-byte character code sets are supported.
EXAMPLES [Toc] [Back]
The time zone adjustment table for the Eastern Time Zone in the United
Hewlett-Packard Company - 1 - HP-UX 11i Version 2: August 2003
EST5EDT [Toc] [Back]
0 3 6 1 1974 0-6 EDT4
0 3 22-28 2 1975 0 EDT4
0 3 24-30 4 1976-1986 0 EDT4
0 3 1-7 4 1987-2038 0 EDT4
0 1 24-30 11 1974 0 EST5
0 1 25-31 10 1975-2038 0 EST5
Normally (as indicated in the first line) Eastern Standard Time is
five hours earlier than UTC. During Daylight Savings time, it changes
to a 4 hour difference. The first time Daylight Savings Time took
effect (second line) was on January 6, 1974 at 3:00 a.m., EDT. Note
that the minute before was 1:59 a.m., EST. The change back to
standard time took effect (sixth line) on the last Sunday in November
of the same year. At that point, the time went from 1:59 a.m. EDT to
1:00 a.m. EST. The transition to Daylight Savings Time since then
has gone from the last Sunday in February (third line) to the last
Sunday in April (fourth line) to the first Sunday in April (fifth
line). The return to standard time for the same period has remained
at the last Sunday in October (seventh line).
AUTHOR [Toc] [Back]
tztab was developed by HP.
FILES [Toc] [Back]
SEE ALSO [Toc] [Back]
date(1), ctime(3C), environ(5).
Hewlett-Packard Company - 2 - HP-UX 11i Version 2: August 2003 [ Back ]