John Howard - Senior Program Manager in the Hyper-V team at Microsoft

Senior Program Manager, Hyper-V team, Windows Core Operating System Division.

Outlook Date Confusion

Outlook Date Confusion

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Here's some wierdness for the day. My collegue Eileen blogged about the Outlook calendar ending on 31st August 4500. As soon as she mentioned it, a light-bulb immediately lit up as I've done many years of Exchange developer stuff in the past ranging from raw MAPI, through CDO 1.21, CDOSys/CDONTS and CDOEx, not forgetting Outlook objects all the way from Outlook 98 through to 2003.... The light was a specific date in the Outlook object model for holding a "null" date. Curiously, and I still have to admit I don't know the answer, the null date value is 1st January 4501. So where did the days from 1st Sept 4500 to 31st Dec 4500 disappear to on the Outlook calendar?

Just to add more fuel to the fire, did you also know that the Outlook calendar starts on 2nd April 1601? I tried to do the maths see the significance of these why these dates were chosen, but couldn't come up with a power of 2 type reason. There are 1059353 days between 2/4/1601 and 31/8/4501. Converting this to seconds/minutes/hours didn't show up anything obvious. Of course, I didn't take into account September 1752 where (in the UK at least) we lost 14 days when switching calendars. However, Outlook doesn't seem to either when running in UK locales, but it's probably a little too far past the event to be that worried. Kevin, with the busy schedule he has may be more concerned though that he's lost lost around 10454400 seconds from his calendar.

Mind you, I've wasted enough seconds thinking about this and given myself a headache. If you happen to know of any deeper meaning, please let me know.

 

Comments
  • Ah yes.. 1752. I remember it well. HR told me I had instantaneously taken a two week vacation, but I had to report to work the next day just the same. <sigh> :)

  • Just had a weird experience with outlook, my calendar opened by itself and started counting backwards finally stopping on the 2nd april 1601. tried doing the maths also to find the significance but got nowhere......... but I'm wondering if there is a time slip due to "leap years"......... should these be added or subtracted from the date?

    I'm running MS office 2007...... or as I prefer to call it "Bill Gates new game called.... Hide the Icon"

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