Because of the trouble we have with the timezones, time formats and winter-/summertime sometimes, I have looked it up and want to give you a short overview, which should eliminate all obscurities hopefully.
Here we go with the facts...
1. GMT (Greenwich Mean Time) is obsolete and was replaced by UTC (Universal Time, Coordinated) nowadays. But it still is the same thing, so merely just the name has changed.
2. UTC does not change with the summertime! That means, whenever you change to summertime, the offset to UTC increases by 1 hour.
3. CET (Central European Time) is used in most European countries and has an offset of +1 hour to UTC. This means CET = UTC +1.
As far as I can see, we just have members from 3 nations which have different timezones than CET: USA, UK and Portugal. UK and Portugal are UTC +0 and the place in the USA where Van and Nosh are located should be UTC -5 (correct me if I'm wrong). Finland would be UTC +2, but we don't have Finnish members members anymore.
For you to check out, here's a map linked from Wikipedia. All red countries have CET and the blue ones have UTC.
4. Summertime (or Daylight Saving Time, DST, which is the correct English term) is used over entire Europe and most parts of the USA. It starts at the last Sunday in March and ends at the last Sunday in October. During summertime, you have to add another hour to the offset towards UTC. Because of this, all people living in Central Europe are at UTC +2 during this time. Towards CET, seen strict, you would also add 1 hour. But be careful, there's also the CEST (Central European Summer Time), which is CET +1 (or UTC +2).
Again, here's a map linked from Wikipedia, which shows the countries using summertime/DST. Blue means summertime is used, orange means summertime was used (but isn't anymore) and red means summertime was never used.
That's it! I hope, everything's clear now.
Coco.
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. Clearer for most if you just use, for example, 7 pm European time imo. These days we only tend to play in Europe to eliminate lag ... if we do ever play in USA it would be appropriate to quote the time in both zones. 