--- old/make/data/tzdata/leapseconds	2018-10-26 09:16:31.182531663 -0400
+++ new/make/data/tzdata/leapseconds	2018-10-26 09:16:30.918531663 -0400
@@ -26,21 +26,25 @@
 # This file is in the public domain.
 
 # This file is generated automatically from the data in the public-domain
-# leap-seconds.list file, which is copied from:
-# ftp://ftp.nist.gov/pub/time/leap-seconds.list
+# leap-seconds.list file, which can be copied from
+# <ftp://ftp.nist.gov/pub/time/leap-seconds.list>
+# or <ftp://ftp.boulder.nist.gov/pub/time/leap-seconds.list>
+# or <ftp://tycho.usno.navy.mil/pub/ntp/leap-seconds.list>.
 # For more about leap-seconds.list, please see
 # The NTP Timescale and Leap Seconds
-# https://www.eecis.udel.edu/~mills/leap.html
+# <https://www.eecis.udel.edu/~mills/leap.html>.
 
 # The International Earth Rotation and Reference Systems Service
 # periodically uses leap seconds to keep UTC to within 0.9 s of UT1
-# (which measures the true angular orientation of the earth in space); see
-# Levine J. Coordinated Universal Time and the leap second.
+# (which measures the true angular orientation of the earth in space)
+# and publishes leap second data in a copyrighted file
+# <https://hpiers.obspm.fr/iers/bul/bulc/Leap_Second.dat>.
+# See: Levine J. Coordinated Universal Time and the leap second.
 # URSI Radio Sci Bull. 2016;89(4):30-6. doi:10.23919/URSIRSB.2016.7909995
-# http://ieeexplore.ieee.org/document/7909995/
+# <https://ieeexplore.ieee.org/document/7909995>.
 # There were no leap seconds before 1972, because the official mechanism
 # accounting for the discrepancy between atomic time and the earth's rotation
-# did not exist until the early 1970s.
+# did not exist.
 
 # The correction (+ or -) is made at the given time, so lines
 # will typically look like:
@@ -48,10 +52,7 @@
 # or
 #	Leap	YEAR	MON	DAY	23:59:59	-	R/S
 
-# If the leapsecond is Rolling (R) the given time is local time.
-# If the leapsecond is Stationary (S) the given time is UTC.
-
-# Leap	YEAR	MONTH	DAY	HH:MM:SS	CORR	R/S
+# If the leap second is Rolling (R) the given time is local time (unused here).
 Leap	1972	Jun	30	23:59:60	+	S
 Leap	1972	Dec	31	23:59:60	+	S
 Leap	1973	Dec	31	23:59:60	+	S
@@ -80,5 +81,9 @@
 Leap	2015	Jun	30	23:59:60	+	S
 Leap	2016	Dec	31	23:59:60	+	S
 
-#	Updated through IERS Bulletin C55
-#	File expires on:  28 December 2018
+# POSIX timestamps for the data in this file:
+#updated 1467936000
+#expires 1561680000
+
+#	Updated through IERS Bulletin C56
+#	File expires on:  28 June 2019