By default, Essbase outlines are calculated from the bottom up: First the values for the children are calculated and then the value for the parent is calculated. Sometimes, however, the value of a child depends upon the value of the parent or the value of another member.
To obtain the correct values for dependent dimensions and members, the outline is first calculated, and then the dimensions and members that are dependent on the calculated values of other dimensions and members are recalculated. Dimensions and members that are calculated on a second pass through the Essbase outline are called two pass calculations.
For example, to calculate the ratio between Sales and Margin, Essbase must calculate Margin (a parent member based on its children, including Sales). To ensure that the ratio calculation is based on a newly calculated Margin figure, tag the Margin % ratio member as a two pass calculation. Essbase calculates the database and then recalculates the Margin % member. The second calculation produces the correct result.
Although two pass calculation is a property that you can give to any member, it works only on members of accounts dimensions, dynamic calculation members, and dynamic calculation and store members. If you assign two pass calculation to other members, Essbase ignores it.