HP C/iX Library Reference Manual (30026-90004)

374 AppendixA
Time Zones
TZTAB Time Zone Adjustment Table
TZTAB Time Zone Adjustment Table
The differences between Coordinated Universal Time (UTC) and local time are described
in table form in the file TZTAB.LIB.SYS. This table can be used in conjunction with
historical information to represent several local areas simultaneously. This file is also used
by mktime() to compute the UTC from the local time.
The TZTAB file contains one or more time zone adjustment entries. The first line of the
entry contains a unique string that is compared to the value of the TZ environment
variable.
The format of the first line of a time zone adjustment entry is:
tzname diff dstzname
where:
tzname Is the time zone name or abbreviation.
diff Is the difference in hours from UTC. Fractional values of diff are
expressed in minutes preceded by a colon. For example, 1:15 equals one
hour and fifteen minutes.
dstzname Is the name or abbreviation of the Daylight Savings Time zone.
The first line of the entry always begins with an alphabetic character.
The second and subsequent lines of each entry contain details about the adjustments for a
time zone. Each line contains seven fields. The seventh field specifies a particular time
zone adjustment. The first through sixth fields describe the time range for the adjustment.
The fields are separated by blanks or tabs. The meanings of each field are as follows:
First field (0-59) Specifies the minute at which a time zone adjustment takes effect.
Second field (0-23) Specifies the hour at which a time zone adjustment takes effect.
Third field (1-31) Specifies the day of the month at which a time zone adjustment takes
effect.
Fourth field (1-12) Specifies the month in which a time zone adjustment takes effect.
Fifth field (1970-1999) Specifies the year in which a time zone adjustment takes effect.
Sixth field (0-6) Specifies the day of the week in which a time zone adjustment takes
effect, with 0 equal to Sunday, 1 to Monday, etc.
The minute, hour, and month fields contain a single number within the range given above
for each. The day of the month, year, and day of the week fields may contain a single
number or a range of numbers separated by a minus sign. Either the day of the month or
the day of the week field must be a range, and the other must be a single number.
The seventh field is a string that describes the time zone adjustment in the following
format:
tznamediff
where: