3 Replies Latest reply: Aug 26, 2012 9:08 AM by Barney-15E
Björn Steiner Level 1 Level 1

I have not upgraded to ML yet, but have to clear one thing in advance.


Mountain Lion added support for week numbers, but according to which are they calculated, ISO or US?


Does ML calendar week follow language (US english = US calendar weeks / GER german = ISO calculation) or location setting (time zone US = US week no. / time zone Europe = ISO)?


Further on, what happens if I synchronize the calendar between two macs by iCloud, one sitting in the US another one sitting in Europe - how does the cal week number synchronize?

  • Barney-15E Level 8 Level 8

    I don't know if this will help, but the First Day of Week setting in the Language & Text system prefs controls where the week numbers display. I'm not sure if there is a different calculation of the week number. It didn't appear to change which week, just where it started, when I moved it around. If the actual week number is calculated differently for each region, the fact that it didn't change may just be a coincidence of the current year.

    Sorry, I can't help with the syncing issue.

  • Björn Steiner Level 1 Level 1

    Not really, calendar week numbering aint easy.


    Variant 1: according to ISO 8601 (09/2006) the week is defined Monday til Sunday and calender week number one is the first one longer then 4 days, containing 4th of January and the first Thursday of a year.


    Variant 2: in the US (and i.e. AUS etc) week starts Sunday and numbers cw1 as the one containing 1st of January.


    Variant 3: the first complete week of a year, but seldom used.


    2010 was such a different year - according to US numbering week one started 2009/12/28, in ISO week one started 2010/01/04. So if you change timezone-language-region(?) the numbering for 2010 should alter - does it?

  • Barney-15E Level 8 Level 8

    For 2010, in US, AUS, NZ, Wk1 starts Dec 27, 2009.

    For UK and Germany, Wk1 starts 4 Jan 2010

    For Ireland, Wk1 starts 3 Jan 2010.


    For all of those, the Region defines the default "Week Starts on " day. When I change the UK region to start later than Monday, the weeks shift backward (ie the week of the 4th is week 2.) So, the Day of week does affect the week numbers.