Restrciting NAST entries while 'print preview' of VA02/03 sales order

Hi experts,

While doing 'printing preview' for the displayed VA03/02 sales order, an entry is created in the NAST table.

The requirement is to not create(or diffrentiate based on some flag) this entry in NAST table while doing 'printing preview' ..but for actual print the entry in NAST table should be created.

Finally the main aim is to differentiate between print preview vs actual print based on NAST entry.

I tried debugging but the parameters for print preview vs actual print are same.

How can the print preview action be distinguished from actual print in such cases.

Thanks