Want to add New field in Requisition and Purchase order i.e. SPAID (Supplier Part Auxiliary ID)

Hello Guys,

HP is one of our supplier, with the help of punch out site associates place orders. Now HP is sending us one more new field information SPAID (Supplier Part Auxiliary ID) in there XML, and we have to insert this value in requisitions and carry forward to POs.

My question is how can i extract this value and put in requisitions, where does extraction takes place. I noticed Punch out site sends us XML via http post, but not sure how can i extract this value and push it into requisitions.

Thanks in Advance, kindly suggest.

Thanks,

Rohish