The usual areas of issues are XML, where a time ending in a Z is Zulu, UTC, not "local time". A time without a Z is "local time" (but local to which end? hence to be avoided). A time with ±HH:MM on the end is a specific time zone. We often see BT see a time and assume UTC when no Z, or local time when a Z it used and sent. It causes no end of issues. To be fair Talk Talk have similar issues on XML. We also see XML from BT with the Z explicitly but the time itself is local time and so everything ends up an hour out. Customers may have seen on clueless that target completion of work in summer is often 00:59:59 the next day (local time) as BT have sent a date/time ending in T23:59:59Z.
It amazes me that this is remotely difficult or not just fixed.
The other classic for a long time was the Microsoft Office invites that would always say meeting at time GMT, e.g. 15:00 GMT, when they meant 15:00 UK local time. So we would not be ready at 15:00 local time, expecting the conference call or whatever at 16:00 (i.e. 15:00 GMT).
This was made worse when Microsoft added a note along the lines of "Times in GMT do not reflect local daylight savings times" or some such, which to me explicitly states they really do mean GMT (UTC) and not BST in such cases. Madness.
Today I have someone in ops suitably annoyed as they normally finish by now, when BT wanted to co-ordinate a simple certificate change at 18:00 BST. At least, today, they finally confirmed the right time, eventually. This is not hard, honest.
We do not perform any cutover during business hours. We have the slot at 18 BST on Thursday , we can have the cutover if its fine for you.
18:00 BST (so therefore 17:00 local time for us here in the UK) on Thursday is fine for us although isn't that in business hours too? We can also do 18:00 UTC.
We can do at 18 BST today. I will send the invite shortly.
Ah, OK, I don't have Exchange so that invitation doesn't mean a lot to me, but parsing the text by hand it says: DTSTART;TZID=GMT Standard Time:20171123T180000 So, OK, it's 18:00 GMT. I can still do 18:00 GMT but it is an hour later than 18:00 BST. You have caused some confusion here. We are no longer in daylight savings and 18:00 BST and 18:00 GMT are an hour different from each other.
I am so sorry James. Yes that’s 18:00 GMT. Apologies for the inconvenience caused.