User exit for PO

Hi friends,

I am working on creating a PO. I have to get all the data into an internal table and send it to an external system to calculate the freight rate.

I have done a similar task for sales order.

For Sales order I have written the code in userexit MV45AFZZ - form userexit_pricing_prepare_tkomp.

So where should i start for purchase order.

Any help on this willl be appericiated and Thanks in Advance.

Shejal.