This setting is only used with the period filtertype
when period_type is relative.

 - filtertype: period
   source: name
   range_from: -1
   range_to: -1
   timestring: '%Y.%m.%d'
   unit: weeks
   week_starts_on: sunday

The value of this setting indicates whether weeks should be measured starting on sunday or monday. Though Monday is the ISO standard, Sunday is frequently preferred.

This setting is only used when unit is set to weeks.

The default value for this setting is sunday.