Cumulative Key Figure (Running Total) - how to use in formula?

Question

We have a scenario where I need to use the cumulative value of a Key Figure in a subsequent formula. The “Cumulated” property setting at the Key Figure level in the query is a “Displayed Data Only” setting, however, so the cumulated values are not available for use in a formula  The individual values are used by BW as opposed to the cumulative values that are displayed in the column.
I’ve tried using the “Cumulated” property at the characteristic level. I am then able to use the displayed cumulative values in a formula. However, I also need to display the individual (not cumulated) Key Figure values in a column. These individual values are no longer available for display if the “Cumulated” property is set at the Characteristic level.
I thought that the “Define Cells” functionality could possible be used, but there is only one Structure in the query, so the “Define Cells” functionality is unavailable. I could not think of a way to use a second structure in the rows, as the rows need to be dynamic (two characteristics, populated based on user input variables).
It may be possible to accomplish this requirement by adding a column using VBA in the SAPBEXonRefresh sub, but use of VBA is not a preferred option, as the query may be run in either the Excel Analyzer or the Web Analyzer.
The infoprovider does not contain a Key Figure field for Cumulative Volumes.
The scenario details:
Rows (Characteristics):
A: Plant (values based on user input variable)
B: Calendar day (values based on user input date variables for start & end dates)
So there is one row for each day within each plant.
Columns (Key Figures):
A: Cumulative Volume at Start of Period (uses user input date variable for start date, and “Constant Value” property. Hidden column.)
B: Daily Volume (for each day in the period defined by the user input variables for start and end dates)
C: Cumulative Volume at End of Each Day (formula, meant to be equal to the sum of the Cumulative Volume at start of period plus the total so far of the Daily volumes. In other words, equal to the sum of Column A plus the running total of Column B).
Does anyone out there have any more ideas on how to accomplish the required Cumulative Volume computation?

Answer 1

Thanks for your reply Jurgen.
I've created a Global Calculated Key Figure (CKF), and have looked at and tried a number of settings in the Properties of this new CKF.
I have not yet been able to make this work for me.
The "Cumulated" property for a Global CKF is also a display-only property. The displayed running total is not used in any formula containing this CKF, only the individual values are used in the formula.
If I select the 'Enhance' option, where exception aggregation can be done as I think you suggested, I do not see a 'cumulated' option. If I select the 'Summation' option for 'Exception Aggregation', then the 'Reference Characteristic' pull-down is not available.
Is there a different 'Exception Aggregation' option I should be using for running totals at the calendar day level?
Or am I unclear on the concept of your suggestion?
Perhaps you're on a later version of BW that has more Exception Aggregation options? (We're on BW3.5)