Should an attachment on the supplier header categorized as “To the Buyer” default as an attachment t

This is counter intuitive to me, but may be the way it works. The attachment is not on the requisition. 

I have not come across this before, usually all attachments for the supplier have been flagged as "to the supplier". 

I am seeing other categories being attached that I did not expect to be on a PO.  The Instance is 11i, but if you know please let me know if there is any difference in R12.

Thank you

Rob