Specifies the start point for the numbering scheme used by the Week and Weekstart functions. Acceptable values are:

• -1 Any odd days in week zero, Monday starts week one (default)
• 0 First week always zero, even if it starts on Monday
• 1 First week always one, even if it starts on Monday
• 2 ISO 8601 week numbers (week one is the first containing a Thursday)