man: document the date:since..until range queries

man/man7/notmuch-search-terms.7

@@ -54,6 +54,8 @@ terms to match against specific portions of an email, (where
 
 	folder:<directory-path>
 
+	date:<since>..<until>
+
 The
 .B from:
 prefix is used to match the name or address of the sender of an email
@@ -104,6 +106,26 @@ contained within particular directories within the mail store. Only
 the directory components below the top-level mail database path are
 available to be searched.
 
+The
+.B date:
+prefix can be used to restrict the results to only messages within a
+particular time range (based on the Date: header) with a range syntax
+of:
+
+	date:<since>..<until>
+
+See \fBDATE AND TIME SEARCH\fR below for details on the range
+expression, and supported syntax for <since> and <until> date and time
+expressions.
+
+The time range can also be specified using timestamps with a syntax
+of:
+
+	<initial-timestamp>..<final-timestamp>
+
+Each timestamp is a number representing the number of seconds since
+1970\-01\-01 00:00:00 UTC.
+
 In addition to individual terms, multiple terms can be
 combined with Boolean operators (
 .BR and ", " or ", " not
@@ -117,20 +139,124 @@ operators, but will have to be protected from interpretation by the
 shell, (such as by putting quotation marks around any parenthesized
 expression).
 
-Finally, results can be restricted to only messages within a
-particular time range, (based on the Date: header) with a syntax of:
+.SH DATE AND TIME SEARCH
 
-	<initial-timestamp>..<final-timestamp>
+notmuch understands a variety of standard and natural ways of
+expressing dates and times, both in absolute terms ("2012-10-24") and
+in relative terms ("yesterday"). Any number of relative terms can be
+combined ("1 hour 25 minutes") and an absolute date/time can be
+combined with relative terms to further adjust it. A non-exhaustive
+description of the syntax supported for absolute and relative terms is
+given below.
 
-Each timestamp is a number representing the number of seconds since
-1970\-01\-01 00:00:00 UTC. This is not the most convenient means of
-expressing date ranges, but until notmuch is fixed to accept a more
-convenient form, one can use the date program to construct
-timestamps. For example, with the bash shell the following syntax would
-specify a date range to return messages from 2009\-10\-01 until the
-current time:
+.RS 4
+.TP 4
+.B The range expression
 
-	$(date +%s \-d 2009\-10\-01)..$(date +%s)
+date:<since>..<until>
+
+The above expression restricts the results to only messages from
+<since> to <until>, based on the Date: header.
+
+<since> and <until> can describe imprecise times, such as "yesterday".
+In this case, <since> is taken as the earliest time it could describe
+(the beginning of yesterday) and <until> is taken as the latest time
+it could describe (the end of yesterday). Similarly,
+date:january..february matches from the beginning of January to the
+end of February.
+
+Currently, we do not support spaces in range expressions. You can
+replace the spaces with '_', or (in most cases) '-', or (in some
+cases) leave the spaces out altogether. Examples in this man page use
+spaces for clarity.
+
+Open-ended ranges are supported (since Xapian 1.2.1), i.e. it's
+possible to specify date:..<until> or date:<since>.. to not limit the
+start or end time, respectively. Pre-1.2.1 Xapian does not report an
+error on open ended ranges, but it does not work as expected either.
+
+Entering date:expr without ".." (for example date:yesterday) won't
+work, as it's not interpreted as a range expression at all. You can
+achieve the expected result by duplicating the expr both sides of ".."
+(for example date:yesterday..yesterday).
+.RE
+
+.RS 4
+.TP 4
+.B Relative date and time
+[N|number] (years|months|weeks|days|hours|hrs|minutes|mins|seconds|secs) [...]
+
+All refer to past, can be repeated and will be accumulated.
+
+Units can be abbreviated to any length, with the otherwise ambiguous
+single m being m for minutes and M for months.
+
+Number can also be written out one, two, ..., ten, dozen,
+hundred. Additionally, the unit may be preceded by "last" or "this"
+(e.g., "last week" or "this month").
+
+When combined with absolute date and time, the relative date and time
+specification will be relative from the specified absolute date and
+time.
+
+Examples: 5M2d, two weeks
+.RE
+
+.RS 4
+.TP 4
+.B Supported absolute time formats
+H[H]:MM[:SS] [(am|a.m.|pm|p.m.)]
+
+H[H] (am|a.m.|pm|p.m.)
+
+HHMMSS
+
+now
+
+noon
+
+midnight
+
+Examples: 17:05, 5pm
+.RE
+
+.RS 4
+.TP 4
+.B Supported absolute date formats
+YYYY-MM[-DD]
+
+DD-MM[-[YY]YY]
+
+MM-YYYY
+
+M[M]/D[D][/[YY]YY]
+
+M[M]/YYYY
+
+D[D].M[M][.[YY]YY]
+
+D[D][(st|nd|rd|th)] Mon[thname] [YYYY]
+
+Mon[thname] D[D][(st|nd|rd|th)] [YYYY]
+
+Wee[kday]
+
+Month names can be abbreviated at three or more characters.
+
+Weekday names can be abbreviated at three or more characters.
+
+Examples: 2012-07-31, 31-07-2012, 7/31/2012, August 3
+.RE
+
+.RS 4
+.TP 4
+.B Time zones
+(+|-)HH:MM
+
+(+|-)HH[MM]
+
+Some time zone codes, e.g. UTC, EET.
+.RE
 
 .SH SEE ALSO