As a US resident, I've rarely had occasion to purchase DL fares priced in a non-USD currency. If I purchase such a non-USD fare (such as a non-US origin one-way flight) and then have to cancel, I expect the ecredit would reflect the purchased non-USD currency.

Here's my question. What happens if I end up with such a non-USD ecredit, and then later wish to use that non-USD ecredit for a USD-priced fare? Does DL require that ecredits only be used for fares priced in that currency, or can I use a non-USD ecredit for a USD-priced fare?