--- zone1970.tab.orig	2025-08-30 06:13:30 UTC
+++ zone1970.tab
@@ -7,9 +7,10 @@
 # civil timestamps have agreed since 1970.  Columns are separated by
 # a single tab.  Lines beginning with ‘#’ are comments.  All text uses
 # UTF-8 encoding.  The columns of the table are as follows:
-#
+
 # 1.  The countries that overlap the timezone, as a comma-separated list
 #     of ISO 3166 2-character country codes.
+#     See the file '/usr/share/misc/iso3166'.
 # 2.  Latitude and longitude of the timezone’s principal location
 #     in ISO 6709 sign-degrees-minutes-seconds format,
 #     either ±DDMM±DDDMM or ±DDMMSS±DDDMMSS,