Partner function

Hi,

I have a query on partner function. I have created one partner function AA and its assigned to procedure FK.

Partner function AA is not maintained any customer master procedures. also its not maintained in sales item procedure i.e. FP

when ever I create a order and if I maintain the partner function AA at sales order header then same pf is available at sales item though the partner fucntion is not maintain in FP. how its copying into sales item level.

regards,