Returns a set of sibling members from the same level as a given member, starting with the first sibling and ending with the given member, as constrained by the Week level in the Time dimension.
Wtd( [ Member_Expression ] )
A valid Multidimensional Expressions (MDX) expression that returns a member.
If a member expression is not specified, the default is the current member of the first hierarchy with a level of type Weeks in the first dimension of type Time (Time.CurrentMember) in the measure group.
The Wtd function is a shortcut function for the PeriodsToDate function where the level is set to Weeks. That is, Wtd(Member_Expression) is equivalent to PeriodsToDate(Week_Level_Expression,Member_Expression).