[tz] [PROPOSED] Cite Rec. ITU-R TF.460-6 for leap seconds

[Paul Eggert]

(Inspired by patch proposed by Chris Woodbury.)
* leapseconds.awk (BEGIN):
* tz-link.html (Precision timekeeping):
Add ITU-R citation.
* leapseconds.awk (BEGIN): Drop mention of rolling leap seconds,
as the ITU-R doesn’t mention them and this script doesn’t generate them.
---
 leapseconds.awk | 16 +++++++++-------
 tz-link.html    |  4 ++++
 2 files changed, 13 insertions(+), 7 deletions(-)
 mode change 100644 => 100755 leapseconds.awk

diff --git a/leapseconds.awk b/leapseconds.awk
old mode 100644
new mode 100755
index 242e9d6..241da92
--- a/leapseconds.awk
+++ b/leapseconds.awk
@@ -16,6 +16,11 @@ BEGIN {
   print "# The NTP Timescale and Leap Seconds"
   print "# <https://www.eecis.udel.edu/~mills/leap.html>."
   print ""
+  print "# The rules for leap seconds are specified in Annex 1 (Time scales) of:"
+  print "# Standard-frequency and time-signal emissions."
+  print "# International Telecommunication Union - Radiocommunication Sector"
+  print "# (ITU-R) Recommendation TF.460-6 (02/2002)"
+  print "# <https://www.itu.int/rec/R-REC-TF.460-6-200202-I/>."
   print "# The International Earth Rotation and Reference Systems Service"
   print "# periodically uses leap seconds to keep UTC to within 0.9 s of UT1"
   print "# (which measures the true angular orientation of the earth in space)"
@@ -29,15 +34,12 @@ BEGIN {
   print "# accounting for the discrepancy between atomic time and the earth's rotation"
   print "# did not exist.  The first (\"1 Jan 1972\") data line in leap-seconds.list"
   print "# does not denote a leap second; it denotes the start of the current definition"
-  print"# of UTC."
+  print "# of UTC."
   print ""
   print "# The correction (+ or -) is made at the given time, so lines"
-  print "# will typically look like:"
-  print "#	Leap	YEAR	MON	DAY	23:59:60	+	R/S"
-  print "# or"
-  print "#	Leap	YEAR	MON	DAY	23:59:59	-	R/S"
-  print ""
-  print "# If the leap second is Rolling (R) the given time is local time (unused here)."
+  print "# typically look like this:"
+  print "# Leap	YEAR	MON	DAY	23:59:60	+	S"
+  print "# A negative leap second's columns 5 and 6 would be '23:59:59' and '-'."
 
   monthabbr[ 1] = "Jan"
   monthabbr[ 2] = "Feb"
diff --git a/tz-link.html b/tz-link.html
index 85fc001..234c04e 100644
--- a/tz-link.html
+++ b/tz-link.html
@@ -929,6 +929,10 @@ scales used by each landed mission on Mars.</li>
 dedicated not only to leap seconds but to precise time and frequency
 in general. It covers the state of the art in amateur timekeeping, and
 how the art has progressed over the past few decades.</li>
+<li>The rules for leap seconds are specified in Annex 1 (Time scales) of <a
+href="https://www.itu.int/rec/R-REC-TF.460-6-200202-I/">Standard-frequency
+and time-signal emissions</a>, International Telecommunication Union –
+Radiocommunication Sector (ITU-R) Recommendation TF.460-6 (02/2002).</li>
 <li><a
 href="https://www.iers.org/IERS/EN/Publications/Bulletins/bulletins.html"><abbr
 title="International Earth Rotation and Reference Systems Service">IERS</abbr>
-- 
2.17.1