[There's a reason that Yoda is the unofficial mascot of SBS. Size indeed matters not.] What time is it? - THE OFFICIAL BLOG OF THE SBS "DIVA"
Sun, Jul 3 2005 17:11 bradley

What time is it?

What time is it?  No, really, what time is it?  If I wanted to meet up with you at 8:00 a.m. tomorrow morning and you were in a different time zone, what's the best way to make sure that I arrange to meet you at the right time? 

It's a little thing that I take for granted but has been nailed on a couple of times and in fact found this very Tablet PC didn't have the little check box checked to ensure that daylight savings time would be automagically converted at the right time.

So here I am doing my rant about the issue that I have about OEM machines not “keeping' that check box even though as you load up the computer you check the box.  So much so you should have heard me and John Levy at the AICPA Tech Conf.  He argues that outlook should not be hooked to the computer time and in fact should be relative, whereas I beleive it has to be based on GMT.

Well imagine my surprise when I've heard of a worse issue than mine.  Because we are a world wide world and global community, we need to worry about what time it is around the world.

Fellow MVP Steven Teiger brings up his headache about time greater than any headache I have.  In his time, the government sets the time zone when they decide and not by standards. 

Can you imagine not having your time automagically taken care of, but rather, on the decision of politicians and thus you have to scramble to make the time change consistently?

If you've never had to unscrew up a Group calendar when the calendars aren't in sync, well you just haven't had fun.

So next time you complain about that annoying check box that doesn't keep track of the time, there's someone else who has to deal with something way more complicated than you do.

Standardization is indeed a good thing.

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# re: What time is it?

Sunday, July 03, 2005 11:13 PM by bradley

I just found this utility a couple of days ago from Microsoft. It's one of their freeware utilities called Microsoft Time Zone and can be found here, http://www.microsoft.com/globaldev/outreach/dnloads/timezone.mspx

I installed it so I could keep track of the time where my sister in Germany is as well as few friends around the world. Pretty slick little utility that just sits in the system tray.

# Time is an almost intractable problem.

Tuesday, July 05, 2005 8:17 AM by bradley

I've spent a large part of my career working with time and date issues, from a project management program to a scheduling system, and there are so very many different issues to deal with that life gets really complicated for any programmer trying to make the computer understand time zones.

Here are a few surprises for the novice:

1. Time zones are not always offset by a whole number of hours. Portions of India and Canada run at offsets that are so-many-hours and a half from GMT. "Newfoundland Time" is a great search phrase to use on this.

2. Daylight Savings Time is not universal, nor universally approved of, nor universally applied.
2.1 Up until relatively recently, the switch to "British Summer Time" from GMT was made based on Naval Research by the British Admiralty, and was set by Act of Parliament on an annual basis. Diaries and calendars were printed with the date of British Summer Time marked with an asterisk, leading to the words "subject to Act of Parliament".
2.2 The state of Arizona does not observe Daylight Saving Time, except for the Navajo Reservation, which does, except for the Hopi Nation inside there, which doesn't.

3. Leap seconds exist. GMT and UTC differ by a fraction of a second, and leap seconds are used to keep that difference to a fraction less than one.

My general advice for anyone writing a program to manage dates and times would be to store every time in GMT / UTC (for most practical purposes they can be considered to be equivalent), and to convert to local time zone when displaying the time, and to convert from the local time zone when reading input. Always provide a way to specify the time zone's name, military code (a letter from A to Z) or offset from GMT, including fractional parts of hours.