Sometimes I feel like I'm on a mission to find all of Outlook's calendar bugs. Some are inconsequential and silly, others are more serious. The silly ones are good for a laugh at Outlook's expense - usually problems with how Outlook displays the data but cause few problems otherwise.
Today's silly bug involves Outlook’s inability to correctly number weeks.
Erik found Outlook 2007 has a problem deciding which week number should be used to end 2012 and start 2013. (This bug also affects Outlook 2010; other versions are not affected as they show the week date only in the navigation calendars.)
"How does Outlook calculate the week numbers? In my part of the world, the first day of the week is Monday. Now if I look at the Outlook calendar and browse towards January 2013 I see something strange: The week from 31 Dec. 2012 to 06 January 2013 has week number 53. The following week however has week number 2. So where is week number 1 of the year 2013?"
Outlook numbers the weeks correctly when the week is set to start on Sunday (set in Tools, Options, Calendar options) but gets confused when the week starts on Monday. The underlying data is correct and the week number shown on the navigation calendar is half correct when you view both Dec 2012 and Jan 2013, only the number drawn on the calendar is wrong.
A screenshot of this anomaly:
Outlook fun fact: Outlook has the world ending on Aug 31, 4500 (the last date for appointments)
More on week numbering...
The first week of the new year often brings questions about which week should be used to start numbering. In Outlook there are 3 options - start on Jan 1, on the first full week, or the first 4 day week. Using the 4 day option is probably the most common and is true to ISO standards (although choosing other than Sunday or Monday for the first day of week might confuse Outlook.) Most governments and corporations will follow the ISO standard.
See ISO week date (wikipedia) to learn more about week numbering.
International standard states the first week with a Thursday in it is calendar week 1