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-.\" This file is in the public domain, so clarified as of
-.\" 2009-05-17 by Arthur David Olson.
-.TH zic 8 "" "Time Zone Database"
-.SH NAME
-zic \- timezone compiler
-.SH SYNOPSIS
-.B zic
-[
-.I option
-\&... ] [
-.I filename
-\&... ]
-.SH DESCRIPTION
-.ie '\(lq'' .ds lq \&"\"
-.el .ds lq \(lq\"
-.ie '\(rq'' .ds rq \&"\"
-.el .ds rq \(rq\"
-.de q
-\\$3\*(lq\\$1\*(rq\\$2
-..
-.ie '\(la'' .ds < <
-.el .ds < \(la
-.ie '\(ra'' .ds > >
-.el .ds > \(ra
-.ie \n(.g \{\
-. ds : \:
-. ds - \f(CR-\fP
-.\}
-.el \{\
-. ds :
-. ds - \-
-.\}
-.ds d " degrees
-.ds m " minutes
-.ds s " seconds
-.ds _ " \&
-.if t \{\
-. if \n(.g .if c \(de .if c \(fm .if c \(sd \{\
-. ds d \(de
-. ds m \(fm
-. ds s \(sd
-. ds _ \|
-. \}
-.\}
-The
-.B zic
-program reads text from the file(s) named on the command line
-and creates the timezone information format (TZif) files
-specified in this input.
-If a
-.I filename
-is
-.q "\*-" ,
-standard input is read.
-.SH OPTIONS
-.TP
-.B "\*-\*-version"
-Output version information and exit.
-.TP
-.B \*-\*-help
-Output short usage message and exit.
-.TP
-.BI "\*-b " bloat
-Output backward-compatibility data as specified by
-.IR bloat .
-If
-.I bloat
-is
-.BR fat ,
-generate additional data entries that work around potential bugs or
-incompatibilities in older software, such as software that mishandles
-the 64-bit generated data.
-If
-.I bloat
-is
-.BR slim ,
-keep the output files small; this can help check for the bugs
-and incompatibilities.
-The default is
-.BR slim ,
-as software that mishandles 64-bit data typically
-mishandles timestamps after the year 2038 anyway.
-Also see the
-.B \*-r
-option for another way to alter output size.
-.TP
-.BI "\*-d " directory
-Create time conversion information files in the named directory rather than
-in the standard directory named below.
-.TP
-.BI "\*-l " timezone
-Use
-.I timezone
-as local time.
-.B zic
-will act as if the input contained a link line of the form
-.sp
-.ti +2
-.ta \w'Link\0\0'u +\w'\fItimezone\fP\0\0'u
-Link \fItimezone\fP localtime
-.sp
-If
-.I timezone
-is
-.BR \*- ,
-any already-existing link is removed.
-.TP
-.BI "\*-L " leapsecondfilename
-Read leap second information from the file with the given name.
-If this option is not used,
-no leap second information appears in output files.
-.TP
-.BI "\*-p " timezone
-Use
-.IR timezone 's
-rules when handling nonstandard
-TZ strings like "EET\*-2EEST" that lack transition rules.
-.B zic
-will act as if the input contained a link line of the form
-.sp
-.ti +2
-Link \fItimezone\fP posixrules
-.sp
-If
-.I timezone
-is
-.q "\*-"
-(the default), any already-existing link is removed.
-.sp
-Unless
-.I timezone is
-.q "\*-" ,
-this option is obsolete and poorly supported.
-Among other things it should not be used for timestamps after the year 2037,
-and it should not be combined with
-.B "\*-b slim"
-if
-.IR timezone 's
-transitions are at standard time or Universal Time (UT) instead of local time.
-.TP
-.BR "\*-r " "[\fB@\fP\fIlo\fP][\fB/@\fP\fIhi\fP]"
-Limit the applicability of output files
-to timestamps in the range from
-.I lo
-(inclusive) to
-.I hi
-(exclusive), where
-.I lo
-and
-.I hi
-are possibly signed decimal counts of seconds since the Epoch
-(1970-01-01 00:00:00 UTC).
-Omitted counts default to extreme values.
-The output files use UT offset 0 and abbreviation
-.q "\*-00"
-in place of the omitted timestamp data.
-For example,
-.q "zic \*-r @0"
-omits data intended for negative timestamps (i.e., before the Epoch), and
-.q "zic \*-r @0/@2147483648"
-outputs data intended only for nonnegative timestamps that fit into
-31-bit signed integers.
-On platforms with GNU
-.BR date ,
-.q "zic \*-r @$(date +%s)"
-omits data intended for past timestamps.
-Although this option typically reduces the output file's size,
-the size can increase due to the need to represent the timestamp range
-boundaries, particularly if
-.I hi
-causes a TZif file to contain explicit entries for
-.RI pre- hi
-transitions rather than concisely representing them
-with an extended POSIX.1-2017 TZ string.
-Also see the
-.B "\*-b slim"
-option for another way to shrink output size.
-.TP
-.BI "\*-R @" hi
-Generate redundant trailing explicit transitions for timestamps
-that occur less than
-.I hi
-seconds since the Epoch, even though the transitions could be
-more concisely represented via the extended POSIX.1-2017 TZ string.
-This option does not affect the represented timestamps.
-Although it accommodates nonstandard TZif readers
-that ignore the extended POSIX.1-2017 TZ string,
-it increases the size of the altered output files.
-.TP
-.BI "\*-t " file
-When creating local time information, put the configuration link in
-the named file rather than in the standard location.
-.TP
-.B \*-v
-Be more verbose, and complain about the following situations:
-.RS
-.PP
-The input specifies a link to a link,
-something not supported by some older parsers, including
-.B zic
-itself through release 2022e.
-.PP
-A year that appears in a data file is outside the range
-of representable years.
-.PP
-A time of 24:00 or more appears in the input.
-Pre-1998 versions of
-.B zic
-prohibit 24:00, and pre-2007 versions prohibit times greater than 24:00.
-.PP
-A rule goes past the start or end of the month.
-Pre-2004 versions of
-.B zic
-prohibit this.
-.PP
-A time zone abbreviation uses a
-.B %z
-format.
-Pre-2015 versions of
-.B zic
-do not support this.
-.PP
-A timestamp contains fractional seconds.
-Pre-2018 versions of
-.B zic
-do not support this.
-.PP
-The input contains abbreviations that are mishandled by pre-2018 versions of
-.B zic
-due to a longstanding coding bug.
-These abbreviations include
-.q L
-for
-.q Link ,
-.q mi
-for
-.q min ,
-.q Sa
-for
-.q Sat ,
-and
-.q Su
-for
-.q Sun .
-.PP
-The output file does not contain all the information about the
-long-term future of a timezone, because the future cannot be summarized as
-an extended POSIX.1-2017 TZ string. For example, as of 2023 this problem
-occurs for Morocco's daylight-saving rules, as these rules are based
-on predictions for when Ramadan will be observed, something that
-an extended POSIX.1-2017 TZ string cannot represent.
-.PP
-The output contains data that may not be handled properly by client
-code designed for older
-.B zic
-output formats. These compatibility issues affect only timestamps
-before 1970 or after the start of 2038.
-.PP
-The output contains a truncated leap second table,
-which can cause some older TZif readers to misbehave.
-This can occur if the
-.B "\*-L"
-option is used, and either an Expires line is present or
-the
-.B "\*-r"
-option is also used.
-.PP
-The output file contains more than 1200 transitions,
-which may be mishandled by some clients.
-The current reference client supports at most 2000 transitions;
-pre-2014 versions of the reference client support at most 1200
-transitions.
-.PP
-A time zone abbreviation has fewer than 3 or more than 6 characters.
-POSIX requires at least 3, and requires implementations to support
-at least 6.
-.PP
-An output file name contains a byte that is not an ASCII letter,
-.q "\*-" ,
-.q "/" ,
-or
-.q "_" ;
-or it contains a file name component that contains more than 14 bytes
-or that starts with
-.q "\*-" .
-.RE
-.SH FILES
-Input files use the format described in this section; output files use
-.BR tzfile (5)
-format.
-.PP
-Input files should be text files, that is, they should be a series of
-zero or more lines, each ending in a newline byte and containing at
-most 2048 bytes counting the newline, and without any NUL bytes.
-The input text's encoding
-is typically UTF-8 or ASCII; it should have a unibyte representation
-for the POSIX Portable Character Set (PPCS)
-\*<https://pubs\*:.opengroup\*:.org/\*:onlinepubs/\*:9699919799/\*:basedefs/\*:V1_chap06\*:.html\*>
-and the encoding's non-unibyte characters should consist entirely of
-non-PPCS bytes. Non-PPCS characters typically occur only in comments:
-although output file names and time zone abbreviations can contain
-nearly any character, other software will work better if these are
-limited to the restricted syntax described under the
-.B \*-v
-option.
-.PP
-Input lines are made up of fields.
-Fields are separated from one another by one or more white space characters.
-The white space characters are space, form feed, carriage return, newline,
-tab, and vertical tab.
-Leading and trailing white space on input lines is ignored.
-An unquoted sharp character (#) in the input introduces a comment which extends
-to the end of the line the sharp character appears on.
-White space characters and sharp characters may be enclosed in double quotes
-(") if they're to be used as part of a field.
-Any line that is blank (after comment stripping) is ignored.
-Nonblank lines are expected to be of one of three types:
-rule lines, zone lines, and link lines.
-.PP
-Names must be in English and are case insensitive.
-They appear in several contexts, and include month and weekday names
-and keywords such as
-.BR "maximum" ,
-.BR "only" ,
-.BR "Rolling" ,
-and
-.BR "Zone" .
-A name can be abbreviated by omitting all but an initial prefix; any
-abbreviation must be unambiguous in context.
-.PP
-A rule line has the form
-.nf
-.ti +2
-.ta \w'Rule\0\0'u +\w'NAME\0\0'u +\w'FROM\0\0'u +\w'1973\0\0'u +\w'\*-\0\0'u +\w'Apr\0\0'u +\w'lastSun\0\0'u +\w'2:00w\0\0'u +\w'1:00d\0\0'u
-.sp
-Rule NAME FROM TO \*- IN ON AT SAVE LETTER/S
-.sp
-For example:
-.ti +2
-.sp
-Rule US 1967 1973 \*- Apr lastSun 2:00w 1:00d D
-.sp
-.fi
-The fields that make up a rule line are:
-.TP
-.B NAME
-Gives the name of the rule set that contains this line.
-The name must start with a character that is neither
-an ASCII digit nor
-.q \*-
-nor
-.q + .
-To allow for future extensions,
-an unquoted name should not contain characters from the set
-.ie \n(.g .q \f(CR!$%&\(aq()*,/:;<=>?@[\e]\(ha\(ga{|}\(ti\fP .
-.el .ie t .q \f(CW!$%&'()*,/:;<=>?@[\e]^\(ga{|}~\fP .
-.el .q !$%&'()*,/:;<=>?@[\e]^`{|}~ .
-.TP
-.B FROM
-Gives the first year in which the rule applies.
-Any signed integer year can be supplied; the proleptic Gregorian calendar
-is assumed, with year 0 preceding year 1.
-Rules can describe times that are not representable as time values,
-with the unrepresentable times ignored; this allows rules to be portable
-among hosts with differing time value types.
-.TP
-.B TO
-Gives the final year in which the rule applies.
-The word
-.B maximum
-(or an abbreviation) means the indefinite future, and the word
-.B only
-(or an abbreviation)
-may be used to repeat the value of the
-.B FROM
-field.
-.TP
-.B \*-
-Is a reserved field and should always contain
-.q \*-
-for compatibility with older versions of
-.BR zic .
-It was previously known as the
-.B TYPE
-field, which could contain values to allow a
-separate script to further restrict in which
-.q types
-of years the rule would apply.
-.TP
-.B IN
-Names the month in which the rule takes effect.
-Month names may be abbreviated.
-.TP
-.B ON
-Gives the day on which the rule takes effect.
-Recognized forms include:
-.nf
-.in +2
-.sp
-.ta \w'Sun<=25\0\0'u
-5 the fifth of the month
-lastSun the last Sunday in the month
-lastMon the last Monday in the month
-Sun>=8 first Sunday on or after the eighth
-Sun<=25 last Sunday on or before the 25th
-.fi
-.in
-.sp
-A weekday name (e.g.,
-.BR "Sunday" )
-or a weekday name preceded by
-.q "last"
-(e.g.,
-.BR "lastSunday" )
-may be abbreviated or spelled out in full.
-There must be no white space characters within the
-.B ON
-field.
-The
-.q <=
-and
-.q >=
-constructs can result in a day in the neighboring month;
-for example, the IN-ON combination
-.q "Oct Sun>=31"
-stands for the first Sunday on or after October 31,
-even if that Sunday occurs in November.
-.TP
-.B AT
-Gives the time of day at which the rule takes effect,
-relative to 00:00, the start of a calendar day.
-Recognized forms include:
-.nf
-.in +2
-.sp
-.ta \w'00:19:32.13\0\0'u
-2 time in hours
-2:00 time in hours and minutes
-01:28:14 time in hours, minutes, and seconds
-00:19:32.13 time with fractional seconds
-12:00 midday, 12 hours after 00:00
-15:00 3 PM, 15 hours after 00:00
-24:00 end of day, 24 hours after 00:00
-260:00 260 hours after 00:00
-\*-2:30 2.5 hours before 00:00
-\*- equivalent to 0
-.fi
-.in
-.sp
-Although
-.B zic
-rounds times to the nearest integer second
-(breaking ties to the even integer), the fractions may be useful
-to other applications requiring greater precision.
-The source format does not specify any maximum precision.
-Any of these forms may be followed by the letter
-.B w
-if the given time is local or
-.q "wall clock"
-time,
-.B s
-if the given time is standard time without any adjustment for daylight saving,
-or
-.B u
-(or
-.B g
-or
-.BR z )
-if the given time is universal time;
-in the absence of an indicator,
-local (wall clock) time is assumed.
-These forms ignore leap seconds; for example,
-if a leap second occurs at 00:59:60 local time,
-.q "1:00"
-stands for 3601 seconds after local midnight instead of the usual 3600 seconds.
-The intent is that a rule line describes the instants when a
-clock/calendar set to the type of time specified in the
-.B AT
-field would show the specified date and time of day.
-.TP
-.B SAVE
-Gives the amount of time to be added to local standard time when the rule is in
-effect, and whether the resulting time is standard or daylight saving.
-This field has the same format as the
-.B AT
-field
-except with a different set of suffix letters:
-.B s
-for standard time and
-.B d
-for daylight saving time.
-The suffix letter is typically omitted, and defaults to
-.B s
-if the offset is zero and to
-.B d
-otherwise.
-Negative offsets are allowed; in Ireland, for example, daylight saving
-time is observed in winter and has a negative offset relative to
-Irish Standard Time.
-The offset is merely added to standard time; for example,
-.B zic
-does not distinguish a 10:30 standard time plus an 0:30
-.B SAVE
-from a 10:00 standard time plus a 1:00
-.BR SAVE .
-.TP
-.B LETTER/S
-Gives the
-.q "variable part"
-(for example, the
-.q "S"
-or
-.q "D"
-in
-.q "EST"
-or
-.q "EDT" )
-of time zone abbreviations to be used when this rule is in effect.
-If this field is
-.q \*- ,
-the variable part is null.
-.PP
-A zone line has the form
-.sp
-.nf
-.ti +2
-.ta \w'Zone\0\0'u +\w'Asia/Amman\0\0'u +\w'STDOFF\0\0'u +\w'Jordan\0\0'u +\w'FORMAT\0\0'u
-Zone NAME STDOFF RULES FORMAT [UNTIL]
-.sp
-For example:
-.sp
-.ti +2
-Zone Asia/Amman 2:00 Jordan EE%sT 2017 Oct 27 01:00
-.sp
-.fi
-The fields that make up a zone line are:
-.TP
-.B NAME
-The name of the timezone.
-This is the name used in creating the time conversion information file for the
-timezone.
-It should not contain a file name component
-.q ".\&"
-or
-.q ".." ;
-a file name component is a maximal substring that does not contain
-.q "/" .
-.TP
-.B STDOFF
-The amount of time to add to UT to get standard time,
-without any adjustment for daylight saving.
-This field has the same format as the
-.B AT
-and
-.B SAVE
-fields of rule lines, except without suffix letters;
-begin the field with a minus sign if time must be subtracted from UT.
-.TP
-.B RULES
-The name of the rules that apply in the timezone or,
-alternatively, a field in the same format as a rule-line SAVE column,
-giving the amount of time to be added to local standard time
-and whether the resulting time is standard or daylight saving.
-If this field is
-.B \*-
-then standard time always applies.
-When an amount of time is given, only the sum of standard time and
-this amount matters.
-.TP
-.B FORMAT
-The format for time zone abbreviations.
-The pair of characters
-.B %s
-is used to show where the
-.q "variable part"
-of the time zone abbreviation goes.
-Alternatively, a format can use the pair of characters
-.B %z
-to stand for the UT offset in the form
-.RI \(+- hh ,
-.RI \(+- hhmm ,
-or
-.RI \(+- hhmmss ,
-using the shortest form that does not lose information, where
-.IR hh ,
-.IR mm ,
-and
-.I ss
-are the hours, minutes, and seconds east (+) or west (\-) of UT.
-Alternatively,
-a slash (/)
-separates standard and daylight abbreviations.
-To conform to POSIX, a time zone abbreviation should contain only
-alphanumeric ASCII characters,
-.q "+"
-and
-.q "\*-".
-By convention, the time zone abbreviation
-.q "\*-00"
-is a placeholder that means local time is unspecified.
-.TP
-.B UNTIL
-The time at which the UT offset or the rule(s) change for a location.
-It takes the form of one to four fields YEAR [MONTH [DAY [TIME]]].
-If this is specified,
-the time zone information is generated from the given UT offset
-and rule change until the time specified, which is interpreted using
-the rules in effect just before the transition.
-The month, day, and time of day have the same format as the IN, ON, and AT
-fields of a rule; trailing fields can be omitted, and default to the
-earliest possible value for the missing fields.
-.IP
-The next line must be a
-.q "continuation"
-line; this has the same form as a zone line except that the
-string
-.q "Zone"
-and the name are omitted, as the continuation line will
-place information starting at the time specified as the
-.q "until"
-information in the previous line in the file used by the previous line.
-Continuation lines may contain
-.q "until"
-information, just as zone lines do, indicating that the next line is a further
-continuation.
-.PP
-If a zone changes at the same instant that a rule would otherwise take
-effect in the earlier zone or continuation line, the rule is ignored.
-A zone or continuation line
-.I L
-with a named rule set starts with standard time by default:
-that is, any of
-.IR L 's
-timestamps preceding
-.IR L 's
-earliest rule use the rule in effect after
-.IR L 's
-first transition into standard time.
-In a single zone it is an error if two rules take effect at the same
-instant, or if two zone changes take effect at the same instant.
-.PP
-If a continuation line subtracts
-.I N
-seconds from the UT offset after a transition that would be
-interpreted to be later if using the continuation line's UT offset and
-rules, the
-.q "until"
-time of the previous zone or continuation line is interpreted
-according to the continuation line's UT offset and rules, and any rule
-that would otherwise take effect in the next
-.I N
-seconds is instead assumed to take effect simultaneously.
-For example:
-.br
-.ne 7
-.nf
-.in +2
-.ta \w'# Rule\0\0'u +\w'NAME\0\0'u +\w'FROM\0\0'u +\w'2006\0\0'u +\w'\*-\0\0'u +\w'Oct\0\0'u +\w'lastSun\0\0'u +\w'2:00\0\0'u +\w'SAVE\0\0'u
-.sp
-# Rule NAME FROM TO \*- IN ON AT SAVE LETTER/S
-Rule US 1967 2006 - Oct lastSun 2:00 0 S
-Rule US 1967 1973 - Apr lastSun 2:00 1:00 D
-.ta \w'# Zone\0\0'u +\w'America/Menominee\0\0'u +\w'STDOFF\0\0'u +\w'RULES\0\0'u +\w'FORMAT\0\0'u
-# Zone NAME STDOFF RULES FORMAT [UNTIL]
-Zone America/Menominee \*-5:00 \*- EST 1973 Apr 29 2:00
- \*-6:00 US C%sT
-.sp
-.in
-.fi
-Here, an incorrect reading would be there were two clock changes on 1973-04-29,
-the first from 02:00 EST (\*-05) to 01:00 CST (\*-06),
-and the second an hour later from 02:00 CST (\*-06) to 03:00 CDT (\*-05).
-However,
-.B zic
-interprets this more sensibly as a single transition from 02:00 CST (\*-05) to
-02:00 CDT (\*-05).
-.PP
-A link line has the form
-.sp
-.nf
-.ti +2
-.ta \w'Link\0\0'u +\w'Europe/Istanbul\0\0'u
-Link TARGET LINK-NAME
-.sp
-For example:
-.sp
-.ti +2
-Link Europe/Istanbul Asia/Istanbul
-.sp
-.fi
-The
-.B TARGET
-field should appear as the
-.B NAME
-field in some zone line or as the
-.B LINK-NAME
-field in some link line.
-The
-.B LINK-NAME
-field is used as an alternative name for that zone;
-it has the same syntax as a zone line's
-.B NAME
-field.
-Links can chain together, although the behavior is unspecified if a
-chain of one or more links does not terminate in a Zone name.
-A link line can appear before the line that defines the link target.
-For example:
-.sp
-.ne 3
-.nf
-.in +2
-.ta \w'Zone\0\0'u +\w'Greenwich\0\0'u
-Link Greenwich G_M_T
-Link Etc/GMT Greenwich
-Zone Etc/GMT\0\00\0\0\*-\0\0GMT
-.sp
-.in
-.fi
-The two links are chained together, and G_M_T, Greenwich, and Etc/GMT
-all name the same zone.
-.PP
-Except for continuation lines,
-lines may appear in any order in the input.
-However, the behavior is unspecified if multiple zone or link lines
-define the same name.
-.PP
-The file that describes leap seconds can have leap lines and an
-expiration line.
-Leap lines have the following form:
-.nf
-.ti +2
-.ta \w'Leap\0\0'u +\w'YEAR\0\0'u +\w'MONTH\0\0'u +\w'DAY\0\0'u +\w'HH:MM:SS\0\0'u +\w'CORR\0\0'u
-.sp
-Leap YEAR MONTH DAY HH:MM:SS CORR R/S
-.sp
-For example:
-.ti +2
-.sp
-Leap 2016 Dec 31 23:59:60 + S
-.sp
-.fi
-The
-.BR YEAR ,
-.BR MONTH ,
-.BR DAY ,
-and
-.B HH:MM:SS
-fields tell when the leap second happened.
-The
-.B CORR
-field
-should be
-.q "+"
-if a second was added
-or
-.q "\*-"
-if a second was skipped.
-The
-.B R/S
-field
-should be (an abbreviation of)
-.q "Stationary"
-if the leap second time given by the other fields should be interpreted as UTC
-or
-(an abbreviation of)
-.q "Rolling"
-if the leap second time given by the other fields should be interpreted as
-local (wall clock) time.
-.PP
-Rolling leap seconds were implemented back when it was not
-clear whether common practice was rolling or stationary,
-with concerns that one would see
-Times Square ball drops where there'd be a
-.q "3... 2... 1... leap... Happy New Year"
-countdown, placing the leap second at
-midnight New York time rather than midnight UTC.
-However, this countdown style does not seem to have caught on,
-which means rolling leap seconds are not used in practice;
-also, they are not supported if the
-.B \*-r
-option is used.
-.PP
-The expiration line, if present, has the form:
-.nf
-.ti +2
-.ta \w'Expires\0\0'u +\w'YEAR\0\0'u +\w'MONTH\0\0'u +\w'DAY\0\0'u
-.sp
-Expires YEAR MONTH DAY HH:MM:SS
-.sp
-For example:
-.ti +2
-.sp
-Expires 2020 Dec 28 00:00:00
-.sp
-.fi
-The
-.BR YEAR ,
-.BR MONTH ,
-.BR DAY ,
-and
-.B HH:MM:SS
-fields give the expiration timestamp in UTC for the leap second table.
-.br
-.ne 22
-.SH "EXTENDED EXAMPLE"
-Here is an extended example of
-.B zic
-input, intended to illustrate many of its features.
-.nf
-.in +2
-.ta \w'# Rule\0\0'u +\w'NAME\0\0'u +\w'FROM\0\0'u +\w'1973\0\0'u +\w'\*-\0\0'u +\w'Apr\0\0'u +\w'lastSun\0\0'u +\w'2:00\0\0'u +\w'SAVE\0\0'u
-.sp
-# Rule NAME FROM TO \*- IN ON AT SAVE LETTER/S
-Rule Swiss 1941 1942 \*- May Mon>=1 1:00 1:00 S
-Rule Swiss 1941 1942 \*- Oct Mon>=1 2:00 0 \*-
-.sp .5
-Rule EU 1977 1980 \*- Apr Sun>=1 1:00u 1:00 S
-Rule EU 1977 only \*- Sep lastSun 1:00u 0 \*-
-Rule EU 1978 only \*- Oct 1 1:00u 0 \*-
-Rule EU 1979 1995 \*- Sep lastSun 1:00u 0 \*-
-Rule EU 1981 max \*- Mar lastSun 1:00u 1:00 S
-Rule EU 1996 max \*- Oct lastSun 1:00u 0 \*-
-.sp
-.ta \w'# Zone\0\0'u +\w'Europe/Zurich\0\0'u +\w'0:29:45.50\0\0'u +\w'RULES\0\0'u +\w'FORMAT\0\0'u
-# Zone NAME STDOFF RULES FORMAT [UNTIL]
-Zone Europe/Zurich 0:34:08 \*- LMT 1853 Jul 16
- 0:29:45.50 \*- BMT 1894 Jun
- 1:00 Swiss CE%sT 1981
- 1:00 EU CE%sT
-.sp
-Link Europe/Zurich Europe/Vaduz
-.sp
-.in
-.fi
-In this example, the EU rules are for the European Union
-and for its predecessor organization, the European Communities.
-The timezone is named Europe/Zurich and it has the alias Europe/Vaduz.
-This example says that Zurich was 34 minutes and 8
-seconds east of UT until 1853-07-16 at 00:00, when the legal offset
-was changed to
-7\*d\*_26\*m\*_22.50\*s,
-which works out to 0:29:45.50;
-.B zic
-treats this by rounding it to 0:29:46.
-After 1894-06-01 at 00:00 the UT offset became one hour
-and Swiss daylight saving rules (defined with lines beginning with
-.q "Rule Swiss")
-apply. From 1981 to the present, EU daylight saving rules have
-applied, and the UTC offset has remained at one hour.
-.PP
-In 1941 and 1942, daylight saving time applied from the first Monday
-in May at 01:00 to the first Monday in October at 02:00.
-The pre-1981 EU daylight-saving rules have no effect
-here, but are included for completeness. Since 1981, daylight
-saving has begun on the last Sunday in March at 01:00 UTC.
-Until 1995 it ended the last Sunday in September at 01:00 UTC,
-but this changed to the last Sunday in October starting in 1996.
-.PP
-For purposes of display,
-.q "LMT"
-and
-.q "BMT"
-were initially used, respectively. Since
-Swiss rules and later EU rules were applied, the time zone abbreviation
-has been CET for standard time and CEST for daylight saving
-time.
-.SH FILES
-.TP
-.I /etc/localtime
-Default local timezone file.
-.TP
-.I /usr/share/zoneinfo
-Default timezone information directory.
-.SH NOTES
-For areas with more than two types of local time,
-you may need to use local standard time in the
-.B AT
-field of the earliest transition time's rule to ensure that
-the earliest transition time recorded in the compiled file is correct.
-.PP
-If,
-for a particular timezone,
-a clock advance caused by the start of daylight saving
-coincides with and is equal to
-a clock retreat caused by a change in UT offset,
-.B zic
-produces a single transition to daylight saving at the new UT offset
-without any change in local (wall clock) time.
-To get separate transitions
-use multiple zone continuation lines
-specifying transition instants using universal time.
-.SH SEE ALSO
-.BR tzfile (5),
-.BR zdump (8)