Defines a start or end day and the week in the month. For example, <dayOfWeek occurrence="First">Sunday</dayOfWeek> reads that an occurrence occurs on Sunday during the first week of the month.
<DayOfWeek> <extension base="WeekDay"> <attribute name="occurrence" type="OccurrenceType"/>
Specifies the days of the week: Sunday, Monday, Tuesday, Wednesday, Thursday, Friday, and Saturday.
Specifies the First, Second, Third, Fourth, Fifth, and last week of the month.