For PO Line Types of 'Amount', how to assign multiple currencies?

Hi All -

For PO Line Types of 'Amount', what would be the best solution when the UOM can be different currencies? Should we define two or more 'Amount' Line Types and assign different currencies? For example: 'Amount-USD' Line Type = USD currency, 'Amount-CAD' Line Type = Canada Dollar, 'Amount-GBP' Line Type = British Pound, etc.

Thanks in Advance