Returns the non-ISO week number of a given date.
This function is only available if the Analysis AddIn is installed.
- returns the 'conventional' non-ISO week number, where week 1 is the week that contains January 1st.
- date is the date as a date-time serial number or as text.
- mode specifies which day is considered the first day of the week: 1 for Sunday, 2 for Monday.
- WEEKNUM_ADD mimics the behaviour of the WEEKNUM function in Excel. Calc's WEEKNUM function returns the international standard ISO8601 week number.
- returns 2. 7Jan10 is a Thursday, and 1Jan10 is the Friday of the preceding week.
- WEEKNUM_ADD is called WEEKNUM in the forthcoming ODFF standard.