Relation between delivery number and Sales order number in APO

Hi All,

I am trying to find out relation between delivery number and its corresponding sales order number. I have delivery number and i want to know its corresponding sales order number in APO system. I know that we can see this relation in /SAPAPO/RRP2 transaction by giving the delivery number and ERP logical system. But I am not able to figure it out from where it is picking up. Most probably from live cache it seems.

Is there any FM or table which can give me this relation.

Regards,

Leona