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-rw-r--r--usr.sbin/zic/zdump.822
1 files changed, 18 insertions, 4 deletions
diff --git a/usr.sbin/zic/zdump.8 b/usr.sbin/zic/zdump.8
index 3a685fd7ea0d..9ac0a03230dd 100644
--- a/usr.sbin/zic/zdump.8
+++ b/usr.sbin/zic/zdump.8
@@ -1,5 +1,7 @@
.\"
-.\" @(#)zdump.8 7.3
+.\" @(#)zdump.8 8.2
+.\" This file is in the public domain, so clarified as of
+.\" 2009-05-17 by Arthur David Olson.
.\" $FreeBSD$
.\"
.Dd June 20, 2004
@@ -12,7 +14,7 @@
.Nm
.Op Fl -version
.Op Fl v
-.Op Fl c Ar cutoffyear
+.Op Fl c Ar [loyear,]hiyear
.Op Ar zonename ...
.Sh DESCRIPTION
The
@@ -40,9 +42,21 @@ Each line ends with
if the given time is Daylight Saving Time or
.Em isdst=0
otherwise.
-.It Fl c Ar cutoffyear
-Cut off the verbose output near the start of the given year.
+.It Fl c Ar loyear,hiyear
+Cut off verbose output near the start of the given year(s).
+By default,
+the program cuts off verbose output near the starts of the years -500 and 2500.
.El
+.Sh LIMITATIONS
+The
+.Fl v
+option may not be used on systems with floating-point time_t values
+that are neither float nor double.
+.Pp
+Time discontinuities are found by sampling the results returned by localtime
+at twelve-hour intervals.
+This works in all real-world cases;
+one can construct artificial time zones for which this fails.
.Sh "SEE ALSO"
.Xr ctime 3 ,
.Xr tzfile 5 ,