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.
If a member expression is not specified, the default is the current member of the dimension of type Time (Time.CurrentMember).
The Wtd function is a shortcut function for the PeriodsToDate function where the level is set to Week. That is,
Wtd(Member_Expression) is equivalent to