When refering to real life times in chat, forums, server announcements, etc, please only use UTC (or more specifically: UTC with offset 0).
And please stop confusing users by using local times like PST, EST, CET, etc. and just do your users the favor of doing a short calculation to convert your time zone to UTC.
Rationale
This is the Internet. Users here come from all over the world from all different time zones. Agreeing on a single time zone for Internet communication should be common sense. If everyone uses their local time zone, we all get confused because we have to recalculate the time. And who wants to remember all those acronyms? ;-)
But if everyone uses the same time zone, things get easier. I chose UTC because it is used in the Internet for lots of important things already (example: e-mail). In Minetest, /last-login gives you an UTC time.
Useful links
- List of time zone abbreviations and their UTC offset: https://www.timeanddate.com/time/zones/
- List of local times: https://www.timeanddate.com/worldclock/
- Current UTC time: http://time.is/UTC
- Wikipedia on UTC: https://en.wikipedia.org/wiki/UTC
Calculation rules
To get the UTC time from a local time, subtract the UTC offset from the local time.
To get the local time from UTC time, add the UTC offset to the UTC time.
When choosing the local time zone, be careful about Daylight Savings Time (DST). In places where it is used, they are technically using 2 time zones: one for winter, one for summer. Chances are, that they have different names as well. Example: In the United Kingdom, time zone is GMT (UTC) in winter and BST (UTC+1) in summer.
Example
Let's pretend you wrote this sentence which you now want to convert to UTC:
Server will be shutdown at 12:34 EST.
Use the 1st link above to look up the UTC offset of EST, which is -5 in this case. So here, we have to subtract -5 hours (in other words: add 5 hours), which will result in 17:34 UTC. This should be the only time you should be telling other people on chat, the forums, etc. from now on.
New sentence:
Server will be shutdown at 17:34 UTC.
Hint
On my computer I have set up two clocks, one “local” clock and one UTC clock for “Internet purposes”, and I suggest you to do the same, it will help a lot. :-)