A lot of talk about production scheduling and cost accounting.
Several Microsoft programs (such as Access 2000 and Excel 2000) support a week numbering scheme through the WEEKNUM function that can be set to number weeks starting either on Sunday or on Monday. Note that the Microsoft week numbers are not always the same as the ISO week numbers. Microsoft defines the first week in the year as the week that contains the 1st of January.
Plus project support weeknum function.
I add a custom function to replace Microsoft WeekNUm with one that is ISO 8601 compliment. The code you need is below
There is an ISO 8601 standard here is all you need ISO 8601 how and why.