When I talk to colleagues I want to write "Let's meet 10am London / 11am Europe", but I want to use an abbreviation.

I used to write "10am GMT / 11am CET". But if it were daylight savings time this would be incorrect, and has tripped me up many times, like when I type into Google "10am GMT in CET".

This website claims that CET in common usage means either so that I am correct to use it:

Warning: Many sources define CET as a constant UTC+1. In common usage however, CET usually refers to the time observed in most of Europe, be it standard time or daylight saving time.

There was another question on here for US, that said PT is the correct term for the observed time in the Pacific time zone region, compared PST and PDT that depend on the time of year.

However, from http://mm.icann.org/pipermail/tz/2015-October/022798.html:

Generally speaking, CET = UTC+1, and CEST = UTC+2. Though in some contexts, CET may be used to identify the pair. It's slightly different than the US, as we have the generic term Pacific Time to cover both PST and PDT, but Europe doesn’t have such a generic term.

I am really surprised how difficult it is to find an acronym for the current observed time in a time zone region.

Also, if a time zone is the time in a region at a particular time of year, what is the official term for the geographic region that a time zone applies to?

There seems to be an official standard for an area Europe/Berlin, but what I am looking for is an acronym for a group of areas that respect the same time zone.

  • Very good question. I would like to specify our office hours in a contract and I'm struggling with the same thing (9 AM - 5 PM "CET or CEST - whatever applies at that particular day" is just not concise enough). – Heinzi Sep 21 '20 at 12:32

CEST or CEDT Central European Summer Time or Daylight Time respectively.

CET in the winter. (Central European Time).

These are from the linked source, timeandate.com

CET would be the general acronym similar to PT. But in the US people don't use PT. We'd say either Pacific (spelled out) or PST/PDT for the designation. (Note, in PST the S is for Standard, not Summer.)

So you could follow suit and say:

Central European or CET/CEST where appropriate.

Because the time only shifts twice a year, you just have to nail down your naming convention by time of year. Winter vs Summer.

  • I want a single acronym for both, like ET in the USA. – vaughan Oct 21 '19 at 18:22
  • @vaughan unfortunately I don't believe it exists. CST is already Central Standard Time. CET is the winter designation and CEST is the summer, though I'd likely use CEDT to avoid confusion with Central European Standard Time. – David M Oct 21 '19 at 18:26
  • The annoyance is that typing "10am AEST in CET" will use CET as Winter Time. I hope they just get rid of Summer Time in 2021 to clear this up. – vaughan Oct 26 '19 at 18:55

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