Thank you for your reply and for having put my question in the mailing lists to which I will enjoy soon. The problem is that according to the downloaded version of the database on the Google site for updates http://code.google.com/p/tzdata/ in 1971 the time zone in Paris wasn't one hour ahead of UTC. Here is part of Paris file in XML version <from>1945-04-02T01:00:00Z</from> <to>1945-09-16T01:00:00Z</to> <dst>true</dst> <offset>7200</offset> <name>WEMT</name> </period> - <period> <from>1945-09-16T01:00:00Z</from> <to>1976-03-28T01:00:00Z</to> <dst>false</dst> <offset>0</offset> <name>WET</name> </period> - <period> Is that file correct ? Katia -----Messaggio originale----- Da: Paul Eggert [mailto:eggert@cs.ucla.edu] Inviato: giovedì 23 settembre 2010 06:37 A: katia@astrologiainlinea.it Cc: tz@elsie.nci.nih.gov Oggetto: Re: FW: Time Zone in Paris Katia wrote:
With regard to the time zone of Paris from 1945 to 1976 it results a strange data that conflicts over other resources credited as Shank, according to your database in 1971 the Time zone Paris was 0.
Sorry, I don't see that problem. According to the tz database, the time zone in Paris was one hour ahead of UTC during that period. This agrees with Shanks & Pottenger 2003 (ISBN 0-035127-88-7); I just now checked my printed copy. It also agrees with the Ephemerides Astronomiques for 1998 from Bureau des Longitudes, according to email that we received on 1997-12-12 from Denis Excoffier. These two sources disagree only about exactly when this long period of UTC+1 ended. Shanks & Pottenger say that it ended on 1976-03-28 at 02:00 local time, whereas Excoffier wrote that it ended at 00:00 UTC, i.e., at 01:00 local time. Currently the tz database agrees with Excoffier, but we always welcome any more-authoritative sources, such as reliable newspapers published at the time.