diff --git a/tz/Makefile b/tz/Makefile
index 5064a19..1136af9 100644
--- a/tz/Makefile
+++ b/tz/Makefile
@@ -945,7 +945,10 @@ check_public: $(VERSION_DEPS)
 		mkdir public.dir
 		ln $(VERSION_DEPS) public.dir
 		cd public.dir && $(MAKE) CFLAGS='$(GCC_DEBUG_FLAGS)' ALL
-		for i in $(TDATA_TO_CHECK) public.dir/tzdata.zi; do \
+		for i in $(TDATA_TO_CHECK) public.dir/tzdata.zi \
+		    public.dir/vanguard.zi public.dir/main.zi \
+		    public.dir/rearguard.zi; \
+		do \
 		  public.dir/zic -v -d public.dir/zoneinfo $$i 2>&1 || exit; \
 		done
 		public.dir/zic -v -d public.dir/zoneinfo-all $(TDATA_TO_CHECK)
diff --git a/tz/NEWS b/tz/NEWS
index 6014b45..a60847b 100644
--- a/tz/NEWS
+++ b/tz/NEWS
@@ -1,5 +1,21 @@
 News for the tz database
 
+Release 2021a - 2021-01-24 10:54:57 -0800
+
+  Changes to future timestamps
+
+    South Sudan changes from +03 to +02 on 2021-02-01 at 00:00.
+    (Thanks to Steffen Thorsen.)
+
+
+Release 2020f - 2020-12-29 00:17:46 -0800
+
+  Change to build procedure
+
+    'make rearguard_tarballs' no longer generates a bad rearguard.zi,
+    fixing a 2020e bug.  (Problem reported by Deborah Goldsmith.)
+
+
 Release 2020e - 2020-12-22 15:14:34 -0800
 
   Briefly:
diff --git a/tz/africa b/tz/africa
index 59cf501..28168cf 100644
--- a/tz/africa
+++ b/tz/africa
@@ -1527,11 +1527,17 @@ Zone	Africa/Khartoum	2:10:08 -	LMT	1931
 			3:00	-	EAT	2017 Nov  1
 			2:00	-	CAT
 
+# From Steffen Thorsen (2021-01-18):
+# "South Sudan will change its time zone by setting the clock back 1
+# hour on February 1, 2021...."
+# from https://eyeradio.org/south-sudan-adopts-new-time-zone-makuei/
+
 # South Sudan
 # Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
 Zone	Africa/Juba	2:06:28 -	LMT	1931
 			2:00	Sudan	CA%sT	2000 Jan 15 12:00
-			3:00	-	EAT
+			3:00	-	EAT	2021 Feb  1 00:00
+			2:00	-	CAT
 
 # Tanzania
 # See Africa/Nairobi.
diff --git a/tz/leap-seconds.list b/tz/leap-seconds.list
index e897a86..3198d65 100644
--- a/tz/leap-seconds.list
+++ b/tz/leap-seconds.list
@@ -204,10 +204,10 @@
 #	current -- the update time stamp, the data and the name of the file
 #	will not change.
 #
-#	Updated through IERS Bulletin C60
-#	File expires on:  28 June 2021
+#	Updated through IERS Bulletin C61
+#	File expires on:  28 December 2021
 #
-#@	3833827200
+#@	3849638400
 #
 2272060800	10	# 1 Jan 1972
 2287785600	11	# 1 Jul 1972
@@ -252,4 +252,4 @@
 #	the hash line is also ignored in the
 #	computation.
 #
-#h 	064356a8 39268b92 76e4d5ef 3e22fae1 0cca529c
+#h 	2ab8253d d4380d28 75f01343 381504f8 8f8a4bfc
diff --git a/tz/tz-link.html b/tz/tz-link.html
index 56ef9e4..abe38d8 100644
--- a/tz/tz-link.html
+++ b/tz/tz-link.html
@@ -352,12 +352,7 @@ <h2 id="protocols">Network protocols for <code><abbr>tz</abbr></code> data</h2>
 <a href="https://devguide.calconnect.org/Time-Zones/TZDS/">TZDIST
 implementations</a> are available.
 The <a href="https://www.ietf.org/mailman/listinfo/tzdist-bis">tzdist-bis
-mailing list</a> discussed the Internet draft <a
-id="TZDIST-Geolocate"
-href="https://tools.ietf.org/html/draft-murchison-tzdist-geolocate">TZDIST
-Geolocate Extension</a> (now expired), which let a client determine its timezone
-from its geographic location using a <a
-href="https://tools.ietf.org/html/rfc5870">'geo' URI</a>.</li>
+mailing list</a> discusses possible extensions.</li>
 <li>The <a href="https://tools.ietf.org/html/rfc5545">
 Internet Calendaring and Scheduling Core Object Specification
 (iCalendar)</a> (Internet <abbr>RFC</abbr> 5445)
@@ -410,11 +405,11 @@ <h2 id="compilers">Other <code><abbr>tz</abbr></code> compilers</h2>
 <li>The <a href="https://howardhinnant.github.io/date/tz.html">Time Zone
 Database Parser</a> is a
 <a href="https://en.wikipedia.org/wiki/C%2B%2B">C++</a> parser and
-runtime library with API <a
-href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/p0355r7.html">adopted
-into the draft standard</a> for
+runtime library with <a
+href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/p0355r7.html">API</a>
+adopted by
 <a href="https://en.wikipedia.org/wiki/C++20">C++20</a>,
-the next iteration of the C++ standard.
+the current iteration of the C++ standard.
 It is freely available under the
 <abbr title="Massachusetts Institute of Technology">MIT</abbr> license.</li>
 <li><a id="ICU" href="http://site.icu-project.org">International Components for
@@ -627,11 +622,6 @@ <h2 id="software">Other <code><abbr>tz</abbr></code>-based time zone software</h
 implementations contain a copy of a 32-bit subset of a recent
 <code><abbr>tz</abbr></code> database in a
 Go-specific format.</li>
-<li><a
-href="http://users.skynet.be/Peter.Verthez/projects/intclock/">International
-clock (intclock)</a> is a clock that displays multiple time zones on
-<abbr>GNU</abbr>/Linux and similar systems. It is freely available
-under the <abbr>GPL</abbr>.</li>
 <li>Microsoft Windows 8.1
 and later has <code><abbr>tz</abbr></code> data and <abbr>CLDR</abbr>
 data (mentioned <a href="#CLDR">below</a>) used by the
@@ -677,10 +667,7 @@ <h2 id="other-dbs">Other time zone databases</h2>
 is Astrodienst's Web version of Shanks and Pottenger's out-of-print
 time zone history atlases
 <a href="https://www.worldcat.org/oclc/468828649">for the US</a> and
-<a href="https://www.worldcat.org/oclc/76950459">for the world</a>,
-now published in <a
-href="https://astrocom.com/astrology-products/software/acs-atlas-software">software</a>
-form by <a href="https://astrocom.com">ACS-Starcrafts</a>.
+<a href="https://www.worldcat.org/oclc/76950459">for the world</a>.
 Although these extensive atlases
 <a href="https://astrologynewsservice.com/opinion/how-astrologers-contributed-to-the-information-age-a-brief-history-of-time/">were
 sources for much of the older <code><abbr>tz</abbr></code> data</a>,
@@ -704,11 +691,13 @@ <h2 id="other-dbs">Other time zone databases</h2>
 <section>
 <h2 id="maps">Maps</h2>
 <ul>
-<li>The <a href="https://www.cia.gov/index.html">United States Central
-Intelligence Agency (<abbr
-title="Central Intelligence Agency">CIA</abbr>)</a> publishes a <a
-href="https://www.cia.gov/library/publications/the-world-factbook/graphics/ref_maps/physical/pdf/standard_time_zones_of_the_world.pdf">time
-zone map</a>; the
+<li>The <a
+href="https://www.cia.gov/the-world-factbook/maps/world-regional/">World
+and Regional Maps section</a> of <em>The World Factbook</em>, published by the
+<a href="https://www.cia.gov">US Central Intelligence
+Agency (<abbr
+title="Central Intelligence Agency">CIA</abbr>)</a>, contains a time
+zone map; the
 <a
 href="https://legacy.lib.utexas.edu/maps/world.html">Perry&ndash;Casta&ntilde;eda
 Library Map Collection</a>
@@ -734,7 +723,9 @@ <h2 id="maps">Maps</h2>
 <section>
 <h2 id="boundaries">Time zone boundaries</h2>
 <p>Geographical boundaries between timezones are available
-from several <a href="https://en.wikipedia.org/wiki/Geolocation">geolocation</a>
+from several <a
+href="https://en.wikipedia.org/wiki/Internet_geolocation">Internet
+geolocation</a>
 services and other sources.</p>
 <ul>
 <li><a href="https://github.com/evansiroky/timezone-boundary-builder">Timezone
@@ -883,10 +874,6 @@ <h2 id="national">National histories of legal time</h2>
 <dd>The Interior Ministry periodically issues <a
 href="ftp://ftp.cs.huji.ac.il/pub/tz/announcements"
 hreflang="he">announcements (in Hebrew)</a>.</dd>
-<dt>Italy</dt>
-<dd>The National Institute of Metrological Research publishes a
-<a href="http://oldsite.inrim.it/res/tf/ora_legale_i.shtml" hreflang="it">table
-of civil time (in Italian)</a>.</dd>
 <dt>Malaysia</dt>
 <dd>See Singapore <a href="#Singapore">below</a>.</dd>
 <dt>Mexico</dt>
diff --git a/tz/ziguard.awk b/tz/ziguard.awk
index e27e799..7d6f7c9 100644
--- a/tz/ziguard.awk
+++ b/tz/ziguard.awk
@@ -37,7 +37,7 @@ DATAFORM != "main" {
 
   # If this line should differ due to Czechoslovakia using negative SAVE values,
   # uncomment the desired version and comment out the undesired one.
-  if (zone == "Europe/Prague" && /1947 Feb 23/) {
+  if (zone == "Europe/Prague" && /^#?[\t ]+[01]:00[\t ]/ && /1947 Feb 23/) {
     if (($(in_comment + 2) != "-") == vanguard) {
       uncomment = in_comment
     } else {
@@ -65,10 +65,11 @@ DATAFORM != "main" {
   # uncomment the desired version and comment out the undesired one.
   Rule_Namibia = /^#?Rule[\t ]+Namibia[\t ]/
   Zone_using_Namibia_rule \
-    = (zone == "Africa/Windhoek" \
+    = (zone == "Africa/Windhoek" && /^#?[\t ]+[12]:00[\t ]/ \
        && ($(in_comment + 2) == "Namibia" \
-	   || (1994 <= $(in_comment + 4) && $(in_comment + 4) <= 2017) \
-	   || in_comment + 3 == NF))
+	   || ($(in_comment + 2) == "-" && $(in_comment + 3) == "CAT" \
+	       && ((1994 <= $(in_comment + 4) && $(in_comment + 4) <= 2017) \
+		   || in_comment + 3 == NF))))
   if (Rule_Namibia || Zone_using_Namibia_rule) {
       if ((Rule_Namibia \
 	   ? ($(in_comment + 9) ~ /^-/ \