diff --git a/mercurial/help.py b/mercurial/help.py
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+++ b/mercurial/help.py
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+# help.py - help data for mercurial
+#
+# Copyright 2006 Matt Mackall <mpm@selenic.com>
+#
+# This software may be used and distributed according to the terms
+# of the GNU General Public License, incorporated herein by reference.
+
+helptable = {
+    "dates|Date Formats":
+    r'''
+    Some commands (backout, commit, tag) allow the user to specify a date.
+    Possible formats for dates are:
+
+YYYY-mm-dd \HH:MM[:SS] [(+|-)NNNN]::
+    This is a subset of ISO 8601, allowing just the recommended notations
+    for date and time. The last part represents the timezone; if omitted,
+    local time is assumed. Examples:
+
+    "2005-08-22 03:27 -0700"
+
+    "2006-04-19 21:39:51"
+
+aaa bbb dd HH:MM:SS YYYY [(+|-)NNNN]::
+    This is the date format used by the C library. Here, aaa stands for
+    abbreviated weekday name and bbb for abbreviated month name. The last
+    part represents the timezone; if omitted, local time is assumed.
+    Examples:
+
+    "Mon Aug 22 03:27:00 2005 -0700"
+
+    "Wed Apr 19 21:39:51 2006"
+
+unixtime offset::
+    This is the internal representation format for dates. unixtime is
+    the number of seconds since the epoch (1970-01-01 00:00 UTC). offset
+    is the offset of the local timezone, in seconds west of UTC (negative
+    if the timezone is east of UTC).
+    Examples:
+
+    "1124706420 25200" (2005-08-22 03:27:00 -0700)
+
+    "1145475591 -7200" (2006-04-19 21:39:51 +0200)
+    ''',
+}
+