Thanks, but that link says Turkish DST starts at 01:00 GMT (i.e., at 03:00 local time) and ends at 01:00 GMT (i.e., at 04:00 local time). This agrees with the current tz database. But Amar Devegowda reported that Turkish DST actually starts at 01:00 local time and ends at 02:00 local time. Steffen Thorsen of timeanddate.com agreed, and cited Turkish newspaper reports from 1996 through 2001.
I'm inclined to go with Devegowda and Thorsen, but what would be helpful is an official source (e.g., a citation from Turkish law) that says exactly when this practice started. So far, all we know is that the current Turkish practice started before 1996, which is a bit vague.
I don't have any authoritative source but I can add a little context to this. Turkey is attempting to join the European Union (it's listed as a candidate country on the <http://wwp.greenwichmeantime.com/time-zone/europe/european-union/> page). This is proving a long and painful process. It may be that Turkey has officially switched to the EU 01:00 UTC clock change time recently as part of this EU application process. It may be that the website is just confused, showing all pages under the european-union directory as using EU rules even if they don't. I would also go with Devegowda and Thorsen, mainly on the basis that I think it's very unlikely that a country that far east would use 01:00 UTC unless forced to by something like EU rules. Newspaper reports of 01:00 local time are much more credible. Peter Ilieve peter@aldie.co.uk