ISO8601 formal definition of a Week is "the week with the year's first Thursday in it "
The idea here is to apply this rule to Tableau as an option to define Week of Year number as European Customers have requested this feature.
Creating this idea to differentiate from http://community.tableausoftware.com/ideas/1020 which was handled in version 8.1x.
Add your voices and support for this feature if it would assist you.
equal descriptions of Week 1 (from WikiPedia)
- the week with 4 January in it,
- the first week with the majority (four or more) of its days in the starting year, and
- the week starting with the Monday in the period 29 December – 4 January.
UPDATE: While not a complete solution, Bora Beran has porvided a helpful workbook that accomplishes defining ISO8601 weeks across years - found here: http://https://public.tableau.com/profile/bora.beran#!/vizhome/Iso8601/iso8601