Originally Posted by
christep
It's only a factor if you increase the number of continents. But even then I believe it would be defined in the currency of the originating country, with the current exchange rate applied to the difference if you wish.
Yes. In my experience it is always calculated in the currency of the originating country - when you add a continent the fare on the original purchase date is used, not the current fare.
This is then converted into 'your' rate at the normal rate for tickets.
This could work against you. If for example you bought a ticket in a different currency, cancel it when the currency is lower than on the purchase date you would get less back, if the currency goes up otherwise you potentially make some money.