ACH File Format

Hi Experts,

I need to add a Header Record '$$ADD ID=NPIUSRF1 BID='NWFACH98000114' to the ACH File while processing DME.

I have gone through the Report Documentation which has a few User exits wherein the Header recored can be modified.

But i just need to ADD a header record to the existing one.

How do I do this ?

Regards,

Somdeb.