Customer Exit Variable for Webi report Publication/Schedule.

Hi All,

I'm trying to wrap my head around how Customer Exit variable works in Bex. I have a reporting requirement where the MKT report is to be scheduled to run everyday only showing previous calendar days data, I am positive I can achieve this with a SAP supplied variable (Current Day-0DAT) with an offset of -1 (Please correct me if i'm wrong here). The concern however is that the Bex query is being used in other important reports as well that might need a broader date range. In short, I'm trying to keep this Bex query open so it can be used for other similar reporting requirements as well and not just serve the daily MKT report for Previous days numbers.

I'am told of a date range set up possibility with customer exit variable within it.Which, when left blank at the run time will apply the inbuilt variable logic and run the MKT report to show only previous day numbers.So this way the Bex query can be used for multiple reporting needs. Is this a genuine solution for my scenario ? If yes, can any one walk me through the process of setting this up and explain in short how this kind of variable works in Bex.

Any help on this will be appreciated.

Thanks

GD