b6cbf7203b
This patch imports the unmodified current version of NetBSD libc. The NetBSD includes are in /nbsd_include, while the libc code itself is split between lib/nbsd_libc and common/lib/libc.
427 lines
12 KiB
Groff
427 lines
12 KiB
Groff
.\" $NetBSD: zic.8,v 1.18 2010/05/30 07:57:08 wiz Exp $
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.\" @(#)zic.8 7.22
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.Dd December 20, 2003
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.Dt ZIC 8
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.Os
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.Sh NAME
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.Nm zic
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.Nd time zone compiler
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.Sh SYNOPSIS
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.Nm
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.Op Fl \-version
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.Op Fl d Ar directory
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.Op Fl L Ar leapsecondfilename
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.Op Fl l Ar localtime
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.Op Fl p Ar posixrules
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.Op Fl s
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.Op Fl v
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.Op Fl y Ar command
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.Op Ar Filename ...
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.Sh DESCRIPTION
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.Nm
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reads text from the file(s) named on the command line
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and creates the time conversion information files specified in this input.
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If a
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.Ar filename
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is
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.Ar \&- ,
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the standard input is read.
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.Pp
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These options are available:
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.Bl -tag -width XXXXXXXXXX -compact
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.It Fl \-version
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Output version information and exit.
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.It Fl d Ar directory
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Create time conversion information files in the named directory rather than
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in the standard directory named below.
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.It Fl L Ar leapsecondfilename
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Read leap second information from the file with the given name.
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If this option is not used,
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no leap second information appears in output files.
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.It Fl l Ar timezone
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Use the given time zone as local time.
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.Nm
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will act as if the input contained a link line of the form
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.Dl Link timezone localtime
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.It Fl p Ar timezone
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Use the given time zone's rules when handling POSIX-format
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time zone environment variables.
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.Nm
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will act as if the input contained a link line of the form
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.Dl Link timezone posixrules
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.It Fl s
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Limit time values stored in output files to values that are the same
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whether they're taken to be signed or unsigned.
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You can use this option to generate SVVS-compatible files.
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.It Fl v
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Complain if a year that appears in a data file is outside the range
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of years representable by
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.Xr time 3
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values.
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Also complain if a time of 24:00
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.Pq which cannot be handled by pre-1998 versions of Nm
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appears in the input.
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.It Fl y Ar command
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Use the given
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.Ar command
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rather than
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.Em yearistype
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when checking year types (see below).
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.Pp
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Input lines are made up of fields.
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Fields are separated from one another by any number of white space characters.
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Leading and trailing white space on input lines is ignored.
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An unquoted sharp character (#) in the input introduces a comment which extends
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to the end of the line the sharp character appears on.
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White space characters and sharp characters may be enclosed in double
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quotes
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.Pq \&"
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.\" XXX "
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if they're to be used as part of a field.
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Any line that is blank (after comment stripping) is ignored.
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Non-blank lines are expected to be of one of three types:
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rule lines, zone lines, and link lines.
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.Pp
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A rule line has the form
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.Dl Rule NAME FROM TO TYPE IN ON AT SAVE LETTER/S
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For example:
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.Dl Rule US 1967 1973 \- Apr lastSun 2:00 1:00 D
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The fields that make up a rule line are:
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.Bl -tag -width "LETTER/S" -compact
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.It NAME
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Gives the (arbitrary) name of the set of rules this rule is part of.
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.It FROM
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Gives the first year in which the rule applies.
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Any integer year can be supplied; the Gregorian calendar is assumed.
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The word
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.Em minimum
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(or an abbreviation) means the minimum year representable as an integer.
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The word
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.Em maximum
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(or an abbreviation) means the maximum year representable as an integer.
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Rules can describe times that are not representable as time values,
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with the unrepresentable times ignored; this allows rules to be portable
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among hosts with differing time value types.
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.It TO
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Gives the final year in which the rule applies.
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In addition to
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.Em minimum
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and
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.Em maximum
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(as above),
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the word
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.Em only
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(or an abbreviation)
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may be used to repeat the value of the
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.Em FROM
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field.
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.It TYPE
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Gives the type of year in which the rule applies.
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If
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.Em TYPE
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is
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.Em \&-
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then the rule applies in all years between
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.Em FROM
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and
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.Em TO
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inclusive.
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If
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.Em TYPE
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is something else, then
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.Nm
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executes the command
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.Pp
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.Ic yearistype Ar year type
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.Pp
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to check the type of a year:
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an exit status of zero is taken to mean that the year is of the given type;
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an exit status of one is taken to mean that the year is not of the given type.
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.It IN
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Names the month in which the rule takes effect.
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Month names may be abbreviated.
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.It ON
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Gives the day on which the rule takes effect.
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Recognized forms include:
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.Bl -tag -width lastSun -compact -offset indent
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.It 5
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the fifth of the month
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.It lastSun
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the last Sunday in the month
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.It lastMon
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the last Monday in the month
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.It Sun\*[Ge]8
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first Sunday on or after the eighth
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.It Sun\*[Le]25
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last Sunday on or before the 25th
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.El
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Names of days of the week may be abbreviated or spelled out in full.
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Note that there must be no spaces within the
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.Em ON
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field.
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.It AT
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Gives the time of day at which the rule takes effect.
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Recognized forms include:
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.Bl -tag -width "1X28X14" -compact -offset indent
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.It 2
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time in hours
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.It 2:00
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time in hours and minutes
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.It 15:00
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24-hour format time (for times after noon)
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.It 1:28:14
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time in hours, minutes, and seconds
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.It \-
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equivalent to 0
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.El
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where hour 0 is midnight at the start of the day,
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and hour 24 is midnight at the end of the day.
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Any of these forms may be followed by the letter
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.Em w
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if the given time is local
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.Dq wall clock
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time,
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.Em s
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if the given time is local
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.Dq standard
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time, or
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.Em u
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(or
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.Em g
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or
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.Em z )
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if the given time is universal time;
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in the absence of an indicator,
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wall clock time is assumed.
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.It SAVE
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Gives the amount of time to be added to local standard time when the rule is in
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effect.
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This field has the same format as the
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.Em AT
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field
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(although, of course, the
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.Em w
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and
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.Em s
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suffixes are not used).
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.It LETTER/S
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Gives the
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.Dq variable part
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(for example, the
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.Dq S
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or
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.Dq D
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in
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.Dq EST
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or
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.Dq EDT )
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of time zone abbreviations to be used when this rule is in effect.
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If this field is
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.Em \&- ,
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the variable part is null.
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.El
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.Pp
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A zone line has the form
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.sp
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.Dl Zone NAME GMTOFF RULES/SAVE FORMAT [UNTILYEAR [MONTH [DAY [TIME]]]]
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For example:
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.Dl Zone Australia/Adelaide 9:30 Aus CST 1971 Oct 31 2:00
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The fields that make up a zone line are:
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.Bl -tag -width "RULES/SAVE" -compact
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.It NAME
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The name of the time zone.
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This is the name used in creating the time conversion information file for the
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zone.
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.It GMTOFF
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The amount of time to add to UTC to get standard time in this zone.
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This field has the same format as the
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.Em AT
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and
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.Em SAVE
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fields of rule lines;
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begin the field with a minus sign if time must be subtracted from UTC.
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.It RULES/SAVE
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The name of the rule(s) that apply in the time zone or,
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alternatively, an amount of time to add to local standard time.
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If this field is
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.Em \&-
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then standard time always applies in the time zone.
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.It FORMAT
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The format for time zone abbreviations in this time zone.
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The pair of characters
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.Em %s
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is used to show where the
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.Dq variable part
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of the time zone abbreviation goes.
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Alternatively,
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a slash
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.Pq \&/
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separates standard and daylight abbreviations.
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.It UNTILYEAR [MONTH [DAY [TIME]]]
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The time at which the UTC offset or the rule(s) change for a location.
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It is specified as a year, a month, a day, and a time of day.
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If this is specified,
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the time zone information is generated from the given UTC offset
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and rule change until the time specified.
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The month, day, and time of day have the same format as the IN, ON, and AT
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fields of a rule; trailing fields can be omitted, and default to the
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earliest possible value for the missing fields.
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.El
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The next line must be a
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.Dq continuation
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line; this has the same form as a zone line except that the
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string
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.Dq Zone
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and the name are omitted, as the continuation line will
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place information starting at the time specified as the
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.Em until
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information in the previous line in the file used by the previous line.
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Continuation lines may contain
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.Em until
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information, just as zone lines do, indicating that the next line is a further
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continuation.
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.Pp
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A link line has the form
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.Dl Link LINK-FROM LINK-TO
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For example:
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.Dl Link Europe/Istanbul Asia/Istanbul
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The
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.Em LINK-FROM
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field should appear as the
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.Em NAME
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field in some zone line;
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the
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.Em LINK-TO
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field is used as an alternative name for that zone.
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.Pp
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Except for continuation lines,
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lines may appear in any order in the input.
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.Pp
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Lines in the file that describes leap seconds have the following form:
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.Dl Leap YEAR MONTH DAY HH:MM:SS CORR R/S
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For example:
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.Dl Leap 1974 Dec 31 23:59:60 + S
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The
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.Em YEAR ,
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.Em MONTH ,
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.Em DAY ,
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and
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.Em HH:MM:SS
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fields tell when the leap second happened.
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The
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.Em CORR
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field
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should be
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.Dq \&+
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if a second was added
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or
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.Dq \&-
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if a second was skipped.
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.\" There's no need to document the following, since it's impossible for more
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.\" than one leap second to be inserted or deleted at a time.
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.\" The C Standard is in error in suggesting the possibility.
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.\" See Terry J Quinn, The BIPM and the accurate measure of time,
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.\" Proc IEEE 79, 7 (July 1991), 894-905.
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.\" or
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.\" .Dq ++
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.\" if two seconds were added
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.\" or
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.\" .Dq --
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.\" if two seconds were skipped.
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The
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.Em R/S
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field
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should be (an abbreviation of)
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.Dq Stationary
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if the leap second time given by the other fields should be interpreted as UTC
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or
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(an abbreviation of)
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.Dq Rolling
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if the leap second time given by the other fields should be interpreted as
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local wall clock time.
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.El
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.Sh EXTENDED EXAMPLE
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Here is an extended example of
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.Ic zic
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input, intended to illustrate many of its features.
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.Bl -column -compact "# Rule" "Swiss" "FROM" "1995" "TYPE" "Oct" "lastSun" "1:00u" "SAVE" "LETTER/S"
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.It # Rule NAME FROM TO TYPE IN ON AT SAVE LETTER/S
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.It Rule Swiss 1940 only - Nov 2 0:00 1:00 S
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.It Rule Swiss 1940 only - Dec 31 0:00 0 -
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.It Rule Swiss 1941 1942 - May Sun>=1 2:00 1:00 S
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.It Rule Swiss 1941 1942 - Oct Sun>=1 0:00 0
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.Pp
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.It Rule EU 1977 1980 - Apr Sun>=1 1:00u 1:00 S
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.It Rule EU 1977 only - Sep lastSun 1:00u 0 -
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.It Rule EU 1978 only - Oct 1 1:00u 0 -
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.It Rule EU 1979 1995 - Sep lastSun 1:00u 0 -
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.It Rule EU 1981 max - Mar lastSun 1:00u 1:00 S
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.It Rule EU 1996 max - Oct lastSun 1:00u 0 -
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.El
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.Pp
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.Bl -column -compact "# Zone" "Europe/Zurich" "0:29:44" "RULES" "FORMAT" "UNTIL"
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.It # Zone NAME GMTOFF RULES FORMAT UNTIL
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.It Zone Europe/Zurich 0:34:08 - LMT 1848 Sep 12
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.It 0:29:44 - BMT 1894 Jun
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.It 1:00 Swiss CE%sT 1981
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.It 1:00 EU CE%sT
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.It Link Europe/Zurich Switzerland
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.El
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.Pp
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In this example, the zone is named Europe/Zurich but it has an alias
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as Switzerland.
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Zurich was 34 minutes and 8 seconds west of GMT until
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1848-09-12 at 00:00, when the offset changed to 29 minutes and 44
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seconds.
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After 1894-06-01 at 00:00 Swiss daylight saving rules (defined
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with lines beginning with "Rule Swiss") apply, and the GMT offset
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became one hour.
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From 1981 to the present, EU daylight saving rules have
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applied, and the UTC offset has remained at one hour.
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.Pp
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In 1940, daylight saving time applied from November 2 at 00:00 to
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December 31 at 00:00.
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In 1941 and 1942, daylight saving time applied
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from the first Sunday in May at 02:00 to the first Sunday in October
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at 00:00.
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The pre-1981 EU daylight-saving rules have no effect
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here, but are included for completeness.
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Since 1981, daylight
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saving has begun on the last Sunday in March at 01:00 UTC.
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Until 1995 it ended the last Sunday in September at 01:00 UTC,
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but this changed to the last Sunday in October starting in 1996.
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.Pp
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For purposes of
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display, "LMT" and "BMT" were initially used, respectively.
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Since
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Swiss rules and later EU rules were applied, the display name for the
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timezone has been CET for standard time and CEST for daylight saving
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time.
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.Sh NOTES
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For areas with more than two types of local time,
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you may need to use local standard time in the
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.Em AT
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field of the earliest transition time's rule to ensure that
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the earliest transition time recorded in the compiled file is correct.
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.Pp
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If,
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for a particular zone,
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a clock advance caused by the start of daylight saving
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coincides with and is equal to
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a clock retreat caused by a change in UTC offset,
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.Ic zic
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produces a single transition to daylight saving at the new UTC offset
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(without any change in wall clock time).
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To get separate transitions
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use multiple zone continuation lines
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specifying transition instants using universal time.
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.Sh FILES
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.Pa /usr/share/zoneinfo
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- standard directory used for created files
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.Sh SEE ALSO
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.Xr ctime 3 ,
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.Xr tzfile 5 ,
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.Xr zdump 8
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.\" @(#)zic.8 8.5
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.\" This file is in the public domain, so clarified as of
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.\" 2009-05-17 by Arthur David Olson.
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