The TZ environment variable

This variable is used to describe the time-zone information that the
locale will use.

The following command sets the standard time zone to CST, sets the
daylight saving time zone to CDT, and sets a difference of 6 hours
between CDT and Coordinated Universal Time (UTC).

	SET TZ=CST6CDT

When only the standard time zone is specified, the default difference
in hours from UTC is 0 instead of 5.

For the TZ variable, the SET command has the following format:


	SET TZ=SSS+h[:m:s]DDD[,sm,sw,sd,st,em,ew,ed,et,shift]

The values for the TZ variable are defined in the following table. The
default values given are for the POSIX C locale, the default locale
supported by IBM C and C++ Compilers.

Var.	Description

SSS 	Standard-timezone identifier. It must be three characters,
  	must begin with a letter, and can contain spaces. Zone names
  	are determined by local or country convention. For example,
  	EST stands for Eastern Standard Time and applies to parts of
  	North America.

h,m,s	The variable h specifies the difference (in hours) between the
	standard time zone and CUT, formerly Greenwich mean time
	(GMT). You can optionally use m to specify minutes after the
	hour, and s to specify seconds after the minute. A positive
	number denotes time zones west of the Greenwich meridian; a
        negative number denotes time zones east of the Greenwich
        meridian. The number must be an integer value.

DDD	Daylight saving time (DST) zone identifier. It must be three
        characters, must begin with a letter, and can contain spaces.

sm	Starting month (1 to 12) of DST.

sw	Starting week (-4 to 4) of DST. Use negative numbers to count
        back from the last week of the month (-1) and positive numbers
        to count from the first week (1).

sd	Starting day of DST.
        0 to 6 if sw != 0
        1 to 31 if sw = 0

st	Starting time (in seconds) of DST.

em	Ending month (1 to 12) of DST.

ew	Ending week (-4 to 4) of DST. Use negative numbers to count
	back from the last week of the month (-1) and positive numbers
	to count from the first week (1).</td>

ed	Ending day of DST.
        0 to 6 if ew != 0
        1 to 31 if ew = 0

et	Ending time of DST (in seconds).

shift	Amount of time change (in seconds).

If you give values for any of sm, sw, sd, st, em, ew, ed, et, or
shift, you must give values for all of them. Otherwise, the entire
statement is considered not valid, and the time zone information is
not changed.
