Send XML as acknowledgment from BPM

Hi Experts

I have scenario where our XI box will receive an XML, so whenever we receive an XML XI should send back another XML as an Acknowledgment. Is there any way I can send an custom XML format as an acknowledgment?

In BPM Send step I could see an Aknowledgment option but there I didnt find any option where I can specify the XML which I want to send as an Aknowledgment.

Is it possible to do this in XI?

Can anyone please let me know If I send a normal Aknowledgment for the request how that format looks like.

Please Help Us.

Regards

Ravi Shankar B.