How to handle NVL function in TOTAL creation in RESA

Hi,

We had a requirement of re-defining a total id in RESA. The New total id needs to discard a specific value from the reason_Code column of sa_tran_head table. Now the reason_code column contain both null value and not null value. While creating the total id from resa front end application, we are getting an option of reason_code not in ('X') . But this condition is not considering the null value.

This can only be obtain through NVL function.

So question is how to include the NVL function in TOTAL_ID defination

Thanks

Suchi