-@cindex general date syntax
-
-@cindex items in date strings
-A @dfn{date} is a string, possibly empty, containing many items
-separated by whitespace. The whitespace may be omitted when no
-ambiguity arises. The empty string means the beginning of today (i.e.,
-midnight). Order of the items is immaterial. A date string may contain
-many flavors of items:
-
-@itemize @bullet
-@item calendar date items
-@item time of the day items
-@item time zone items
-@item day of the week items
-@item relative items
-@item pure numbers.
-@end itemize
-
-@noindent We describe each of these item types in turn, below.
-
-@cindex numbers, written-out
-@cindex ordinal numbers
-@findex first @r{in date strings}
-@findex next @r{in date strings}
-@findex last @r{in date strings}
-A few numbers may be written out in words in most contexts. This is
-most useful for specifying day of the week items or relative items (see
-below). Here is the list: @samp{first} for 1, @samp{next} for 2,
-@samp{third} for 3, @samp{fourth} for 4, @samp{fifth} for 5,
-@samp{sixth} for 6, @samp{seventh} for 7, @samp{eighth} for 8,
-@samp{ninth} for 9, @samp{tenth} for 10, @samp{eleventh} for 11 and
-@samp{twelfth} for 12. Also, @samp{last} means exactly @math{-1}.
-
-@cindex months, written-out
-When a month is written this way, it is still considered to be written
-numerically, instead of being ``spelled in full''; this changes the
-allowed strings.
-
-@cindex case, ignored in dates
-@cindex comments, in dates
-Alphabetic case is completely ignored in dates. Comments may be introduced
-between round parentheses, as long as included parentheses are properly
-nested. Hyphens not followed by a digit are currently ignored. Leading
-zeros on numbers are ignored.
-
-
-@node Calendar date item, Time of day item, General date syntax, Date input formats
-@section Calendar date item
-
-@cindex calendar date item
-
-A @dfn{calendar date item} specifies a day of the year. It is
-specified differently, depending on whether the month is specified
-numerically or literally. All these strings specify the same calendar date:
-
-@example
-1970-09-17 # ISO 8601.
-70-9-17 # This century assumed by default.
-70-09-17 # Leading zeros are ignored.
-9/17/72 # Common U.S. writing.
-24 September 1972
-24 Sept 72 # September has a special abbreviation.
-24 Sep 72 # Three-letter abbreviations always allowed.
-Sep 24, 1972
-24-sep-72
-24sep72
-@end example
-
-The year can also be omitted. In this case, the last specified year is
-used, or the current year if none. For example:
-
-@example
-9/17
-sep 17
-@end example
-
-Here are the rules.
-
-@cindex ISO 8601 date format
-@cindex date format, ISO 8601
-For numeric months, the ISO 8601 format
-@samp{@var{year}-@var{month}-@var{day}} is allowed, where @var{year} is
-any positive number, @var{month} is a number between 01 and 12, and
-@var{day} is a number between 01 and 31. A leading zero must be present
-if a number is less than ten. If @var{year} is less than 100, then 1900
-is added to it to force a date in this century. The construct
-@samp{@var{month}/@var{day}/@var{year}}, popular in the United States,
-is accepted. Also @samp{@var{month}/@var{day}}, omitting the year.
-
-@cindex month names in date strings
-@cindex abbreviations for months
-Literal months may be spelled out in full: @samp{January},
-@samp{February}, @samp{March}, @samp{April}, @samp{May}, @samp{June},
-@samp{July}, @samp{August}, @samp{September}, @samp{October},
-@samp{November} or @samp{December}. Literal months may be abbreviated
-to their first three letters, possibly followed by an abbreviating dot.
-It is also permitted to write @samp{Sept} instead of @samp{September}.
-
-When months are written literally, the calendar date may be given as any
-of the following:
-
-@example
-@var{day} @var{month} @var{year}
-@var{day} @var{month}
-@var{month} @var{day} @var{year}
-@var{day}-@var{month}-@var{year}
-@end example
-
-Or, omitting the year:
-
-@example
-@var{month} @var{day}
-@end example
-
-
-@node Time of day item, Timezone item, Calendar date item, Date input formats
-@section Time of day item
-
-@cindex time of day item
-
-A @dfn{time of day item} in date strings specifies the time on a given
-day. Here are some examples, all of which represent the same time:
-
-@example
-20:02:0
-20:02
-8:02pm
-20:02-0500 # In EST (Eastern U.S. Standard Time).
-@end example
-
-More generally, the time of the day may be given as
-@samp{@var{hour}:@var{minute}:@var{second}}, where @var{hour} is
-a number between 0 and 23, @var{minute} is a number between 0 and
-59, and @var{second} is a number between 0 and 59. Alternatively,
-@samp{:@var{second}} can be omitted, in which case it is taken to
-be zero.
-
-@findex am @r{in date strings}
-@findex pm @r{in date strings}
-@findex midnight @r{in date strings}
-@findex noon @r{in date strings}
-If the time is followed by @samp{am} or @samp{pm} (or @samp{a.m.}
-or @samp{p.m.}), @var{hour} is restricted to run from 1 to 12, and
-@samp{:@var{minute}} may be omitted (taken to be zero). @samp{am}
-indicates the first half of the day, @samp{pm} indicates the second
-half of the day. In this notation, 12 is the predecessor of 1:
-midnight is @samp{12am} while noon is @samp{12pm}.
-(This is the zero-oriented interpretation of @samp{12am} and @samp{12pm},
-as opposed to the old tradition derived from Latin
-which uses @samp{12m} for noon and @samp{12pm} for midnight.)
-
-@cindex timezone correction
-@cindex minutes, timezone correction by
-The time may alternatively be followed by a timezone correction,
-expressed as @samp{@var{s}@var{hh}@var{mm}}, where @var{s} is @samp{+}
-or @samp{-}, @var{hh} is a number of zone hours and @var{mm} is a number
-of zone minutes. When a timezone correction is given this way, it
-forces interpretation of the time in UTC, overriding any previous
-specification for the timezone or the local timezone. The @var{minute}
-part of the time of the day may not be elided when a timezone correction
-is used. This is the only way to specify a timezone correction by
-fractional parts of an hour.
-
-Either @samp{am}/@samp{pm} or a timezone correction may be specified,
-but not both.
-
-
-@node Timezone item, Day of week item, Time of day item, Date input formats
-@section Timezone item
-
-@cindex timezone item
-
-A @dfn{timezone item} specifies an international timezone, indicated by
-a small set of letters. Any included period is ignored. Military
-timezone designations use a single letter. Currently, only integral
-zone hours may be represented in a timezone item. See the previous
-section for a finer control over the timezone correction.
-
-Here are many non-daylight-savings-time timezones, indexed by the zone
-hour value.
-
-@table @asis
-@item +000
-@cindex Greenwich Mean Time
-@cindex Universal Coordinated Time
-@cindex Western European Time
-@samp{GMT} for Greenwich Mean, @samp{UT} or @samp{UTC} for Universal
-(Coordinated), @samp{WET} for Western European and @samp{Z} for
-militaries.
-@item +100
-@cindex West African Time
-@samp{WAT} for West Africa and
-@samp{A} for militaries.
-@item +200
-@cindex Azores Time
-@samp{AT} for Azores and @samp{B} for militaries.
-@item +300
-@samp{C} for militaries.
-@item +400
-@cindex Atlantic Standard Time
-@samp{AST} for Atlantic Standard and @samp{D} for militaries.
-@item +500
-@cindex Eastern Standard Time
-@samp{E} for militaries and @samp{EST} for Eastern Standard.
-@item +600
-@cindex Central Standard Time
-@samp{CST} for Central Standard and @samp{F} for militaries.
-@item +700
-@cindex Mountain Standard Time
-@samp{G} for militaries and @samp{MST} for Mountain Standard.
-@item +800
-@cindex Pacific Standard Time
-@samp{H} for militaries and @samp{PST} for Pacific Standard.
-@item +900
-@cindex Yukon Standard Time
-@samp{I} for militaries and @samp{YST} for Yukon Standard.
-@item +1000
-@cindex Alaska-Hawaii Time
-@cindex Central Alaska Time
-@cindex Hawaii Standard Time
-@samp{AHST} for Alaska-Hawaii Standard, @samp{CAT} for Central Alaska,
-@samp{HST} for Hawaii Standard and @samp{K} for militaries.
-@item +1100
-@cindex Nome Standard Time
-@samp{L} for militaries and @samp{NT} for Nome.
-@item +1200
-@cindex International Date Line West
-@samp{IDLW} for International Date Line West and @samp{M} for
-militaries.
-@item -100
-@cindex Central European Time
-@cindex Middle European Time
-@cindex Middle European Winter Time
-@cindex French Winter Time
-@cindex Swedish Winter Time
-@samp{CET} for Central European, @samp{FWT} for French Winter,
-@samp{MET} for Middle European, @samp{MEWT} for Middle European
-Winter, @samp{N} for militaries and @samp{SWT} for Swedish Winter.
-@item -200
-@cindex Eastern European Time
-@cindex USSR Zone
-@samp{EET} for Eastern European, USSR Zone 1 and @samp{O} for militaries.
-@item -300
-@cindex Baghdad Time
-@samp{BT} for Baghdad, USSR Zone 2 and @samp{P} for militaries.
-@item -400
-@samp{Q} for militaries and @samp{ZP4} for USSR Zone 3.
-@item -500
-@samp{R} for militaries and @samp{ZP5} for USSR Zone 4.
-@item -600
-@samp{S} for militaries and @samp{ZP6} for USSR Zone 5.
-@item -700
-@cindex West Australian Standard Time
-@samp{T} for militaries and @samp{WAST} for West Australian Standard.
-@item -800
-@cindex China Coast Time
-@samp{CCT} for China Coast, USSR Zone 7 and @samp{U} for militaries.
-@item -900
-@cindex Japan Standard Time
-@samp{JST} for Japan Standard, USSR Zone 8 and @samp{V} for militaries.
-@item -1000
-@cindex East Australian Standard Time
-@cindex Guam Standard Time
-@samp{EAST} for East Australian Standard, @samp{GST} for Guam
-Standard, USSR Zone 9 and @samp{W} for militaries.
-@item -1100
-@samp{X} for militaries.
-@item -1200
-@cindex International Date Line East
-@cindex New Zealand Standard Time
-@samp{IDLE} for International Date Line East, @samp{NZST} for
-New Zealand Standard, @samp{NZT} for New Zealand and @samp{Y} for
-militaries.
-@end table
-
-@cindex daylight savings time
-Here are many DST timezones, indexed by the zone hour value. Also, by
-following a non-DST timezone by the string @samp{DST} in a separate word
-(that is, separated by some whitespace), the corresponding DST timezone
-may be specified.
-
-@table @asis
-@item 0
-@samp{BST} for British Summer.
-@item +400
-@samp{ADT} for Atlantic Daylight.
-@item +500
-@samp{EDT} for Eastern Daylight.
-@item +600
-@samp{CDT} for Central Daylight.
-@item +700
-@samp{MDT} for Mountain Daylight.
-@item +800
-@samp{PDT} for Pacific Daylight.
-@item +900
-@samp{YDT} for Yukon Daylight.
-@item +1000
-@samp{HDT} for Hawaii Daylight.
-@item -100
-@samp{MEST} for Middle European Summer, @samp{MESZ} for Middle European
-Summer, @samp{SST} for Swedish Summer and @samp{FST} for French Summer.
-@item -700
-@samp{WADT} for West Australian Daylight.
-@item -1000
-@samp{EADT} for Eastern Australian Daylight.
-@item -1200
-@samp{NZDT} for New Zealand Daylight.
-@end table
-
-
-@node Day of week item, Relative item in date strings, Timezone item, Date input formats
-@section Day of week item
-
-@cindex day of week item
-
-The explicit mention of a day of the week will forward the date
-(only if necessary) to reach that day of the week in the future.
-
-Days of the week may be spelled out in full: @samp{Sunday},
-@samp{Monday}, @samp{Tuesday}, @samp{Wednesday}, @samp{Thursday},
-@samp{Friday} or @samp{Saturday}. Days may be abbreviated to their
-first three letters, optionally followed by a period. The special
-abbreviations @samp{Tues} for @samp{Tuesday}, @samp{Wednes} for
-@samp{Wednesday} and @samp{Thur} or @samp{Thurs} for @samp{Thursday} are
-also allowed.
-
-@findex next @var{day}
-@findex last @var{day}
-A number may precede a day of the week item to move forward
-supplementary weeks. It is best used in expression like @samp{third
-monday}. In this context, @samp{last @var{day}} or @samp{next
-@var{day}} is also acceptable; they move one week before or after
-the day that @var{day} by itself would represent.
-
-A comma following a day of the week item is ignored.
-
-
-@node Relative item in date strings, Pure numbers in date strings, Day of week item, Date input formats
-@section Relative item in date strings
-
-@cindex relative items in date strings
-@cindex displacement of dates
-
-@dfn{Relative items} adjust a date (or the current date if none) forward
-or backward. The effects of relative items accumulate. Here are some
-examples:
-
-@example
-1 year
-1 year ago
-3 years
-2 days
-@end example
-
-@findex year @r{in date strings}
-@findex month @r{in date strings}
-@findex fortnight @r{in date strings}
-@findex week @r{in date strings}
-@findex day @r{in date strings}
-@findex hour @r{in date strings}
-@findex minute @r{in date strings}
-The unit of time displacement may be selected by the string @samp{year}
-or @samp{month} for moving by whole years or months. These are fuzzy
-units, as years and months are not all of equal duration. More precise
-units are @samp{fortnight} which is worth 14 days, @samp{week} worth 7
-days, @samp{day} worth 24 hours, @samp{hour} worth 60 minutes,
-@samp{minute} or @samp{min} worth 60 seconds, and @samp{second} or
-@samp{sec} worth one second. An @samp{s} suffix on these units is
-accepted and ignored.
-
-@findex ago @r{in date strings}
-The unit of time may be preceded by a multiplier, given as an optionally
-signed number. Unsigned numbers are taken as positively signed. No
-number at all implies 1 for a multiplier. Following a relative item by
-the string @samp{ago} is equivalent to preceding the unit by a
-multiplicator with value @math{-1}.
-
-@findex day @r{in date strings}
-@findex tomorrow @r{in date strings}
-@findex yesterday @r{in date strings}
-The string @samp{tomorrow} is worth one day in the future (equivalent
-to @samp{day}), the string @samp{yesterday} is worth
-one day in the past (equivalent to @samp{day ago}).
-
-@findex now @r{in date strings}
-@findex today @r{in date strings}
-@findex this @r{in date strings}
-The strings @samp{now} or @samp{today} are relative items corresponding
-to zero-valued time displacement, these strings come from the fact
-a zero-valued time displacement represents the current time when not
-otherwise change by previous items. They may be used to stress other
-items, like in @samp{12:00 today}. The string @samp{this} also has
-the meaning of a zero-valued time displacement, but is preferred in
-date strings like @samp{this thursday}.
-
-When a relative item makes the resulting date to cross the boundary
-between DST and non-DST (or vice-versa), the hour is adjusted according
-to the local time.
-
-
-@node Pure numbers in date strings, Authors of getdate, Relative item in date strings, Date input formats
-@section Pure numbers in date strings
-
-@cindex pure numbers in date strings
-
-The precise intepretation of a pure decimal number is dependent of
-the context in the date string.
-
-If the decimal number is of the form @var{yyyy}@var{mm}@var{dd} and no
-other calendar date item (@pxref{Calendar date item}) appears before it
-in the date string, then @var{yyyy} is read as the year, @var{mm} as the
-month number and @var{dd} as the day of the month, for the specified
-calendar date.
-
-If the decimal number is of the form @var{hh}@var{mm} and no other time
-of day item appears before it in the date string, then @var{hh} is read
-as the hour of the day and @var{mm} as the minute of the hour, for the
-specified time of the day. @var{mm} can also be omitted.
-
-If both a calendar date and a time of day appear to the left of a number
-in the date string, but no relative item, then the number overrides the
-year.
-
-
-@node Authors of getdate, , Pure numbers in date strings, Date input formats
-@section Authors of @code{getdate}
-
-@cindex authors of @code{getdate}
-
-@cindex Bellovin, Steven M.
-@cindex Salz, Rich
-@cindex Berets, Jim
-@cindex MacKenzie, David
-@cindex Meyering, Jim
-@code{getdate} was originally implemented by Steven M. Bellovin
-(@samp{smb@@research.att.com}) while at the University of North Carolina
-at Chapel Hill. The code was later tweaked by a couple of people on
-Usenet, then completely overhauled by Rich $alz (@samp{rsalz@@bbn.com})
-and Jim Berets (@samp{jberets@@bbn.com}) in August, 1990. Various
-revisions for the GNU system were made by David MacKenzie, Jim Meyering,
-and others.
-
-@cindex Pinard, F.
-@cindex Berry, K.
-This chapter was originally produced by Fran@,{c}ois Pinard
-(@samp{pinard@@iro.umontreal.ca}) from the @file{getdate.y} source code,
-and then edited by K.@: Berry (@samp{kb@@cs.umb.edu}).
-
-@node Formats, Media, Date input formats, Top