Change variable value after user executes

Hi all!

I would like to know if it is possible to change a value entered for a variable by the user after they press execute in a BEx workbook. For example if for calendar year/month they do not enter a value, then I would like to enter the current month via an exit (probably ZXRSRU01), but only after they've pressed execute.

Ideally this workbook would be used for broadcasting as well as online execution.

Troy