European time zones [forwarded message from cgcha!wtho]

I've attached a note I received from Tom Hofmann,
slightly edited at Tom's request.

				--ado

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Date: Wed, 28 Jan 87 16:56:27 -0100
From: seismo!mcvax!cgcha!wtho (Tom Hofmann)
Message-Id: <8701281556.AA22174 at cgcha.uucp>
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Subject: Time zone handling
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Let me say something about European time rules.  First of all,
I'm surprised to find the zone MET for Central Europe in
file 'europe'.  The correct expression is CET (Central European
Time), although it's not the first time I found the expression 
MET.  Maybe the best is a link between MET and CET.

Secondly, the European time rules are much more complex than
described in 'europe'.  It is standardized since 1981, when
most European countries started DST.  Before that year, only
a few countries (UK, France, Italy) had DST, each according
to national rules.  In 1981, however, DST started on
'Apr firstSun', and not on 'Mar lastSun' as in the following
years.  So we should set 1981 for FROM, and ignore the past.  
But also since 1981 there are some more national exceptions 
than listed in 'europe': Switzerland, for example, joined DST 
one year later, Denmark ended DST on 'Oct 1' instead of 'Sep 
lastSun' in 1981---I don't know how they handle things now.

Finally, DST is always from 'Apr 1' to 'Oct 1' in the
Soviet Union (as far as I know).  

'europe' should be corrected in that sense, but perhaps you 
better make a query to Usenet first---maybe you'll find somone 
who knows more about national exceptions to European time
rules.

Tom Hofmann, Scientific Computer Center, CIBA-GEIGY AG,
4002 Basle, Switzerland
UUCP: ...!mcvax!cernvax!cgcha!wtho