return weekday number according to ISO8601 rules

[Carl_H]

I have the following M Code that I need to adjust so that it follows the ISO8601 rule (Week 1 2021 should be 2021-01-04 to 2021-01-10) which my code currently does not consider.

I tried to google but was not able to adjust it properly so therefore I would like to know if you can help me out.

#"Inserted Invoice Week" = Table.AddColumn(#"Inserted Invoice Year", "Invoice Week", each Date.WeekOfYear([Invoice Date]), Int64.Type),