Yes, that is possible. I can already Pay an Invoice in multiple Currencies. That isn’t my problem.
My problem is about computing Cost. That was my reasoning for having a Currency parameter in the Inventory Item. It seems to be the most logical choice to me.
The other suggestion of having the parameter in the Warehouse definition seems like the next-most logical choice, since we should be able to assume that the Invoices from a particular Supplier are always in the same Currency.
Anyway, you will probably know what is best. What is your idea on where to put the Currency parameter?