This recent glitches with %z-related lines in the Portugal data lead me to think that it's time to start using %z in the main format. For example, instead of this:
-2:00 Port -02/-01 1942 Apr 25 22:00s -2:00 Port +00 1942 Aug 15 22:00s -2:00 Port -02/-01 1943 Apr 17 22:00s -2:00 Port +00 1943 Aug 28 22:00s -2:00 Port -02/-01 1944 Apr 22 22:00s -2:00 Port +00 1944 Aug 26 22:00s -2:00 Port -02/-01 1945 Apr 21 22:00s -2:00 Port +00 1945 Aug 25 22:00s -2:00 Port -02/-01 1966 Apr 3 2:00 -1:00 Port -01/+00 1983 Sep 25 1:00s -1:00 W-Eur -01/+00 1992 Sep 27 1:00s
the 'europe' file should contain this:
-2:00 Port %z 1966 Apr 3 2:00 -1:00 Port %z 1983 Sep 25 1:00s -1:00 W-Eur %z 1992 Sep 27 1:00s
This would eventually simplify future maintenance and help avoid similar glitches in the future. It's reasonable to move %z to main format now, as zic has supported %z since release 2015f.