Defining local attributes in Global BPA

The Purchasing user guide says we can optionally define local attributes for Global agreement. This includes currency as well. Where we define this local attributes in the GBPA? If the purchasing org has different functional currency than owning org then how can we define the local attribute of currency for those purchasing orgs?

Creating and Using a Global Agreement

• Create a Global Agreement in an Operating Unit (a Contract Purchase Agreement with the Global box and Enable All Sites box checked) - (N) Purchase Orders > Purchase Orders.
• Enable the Agreement in multiple Operating Units. (N) Purchase Orders > Purchase Orders > Tools > Enable Organizations.