Oh, this reminds me of my first job out of college at a Swiss bank. Apparently every time a currency conversion was done in a particular model, there was a routine that translated back and forth between the pre-Euro currency and Euro at the conversion rate. So a USD-EUR transaction with a party in France would be run as USD-FRF --> FRF-EUR. All in COBOL. As a result, every so often, you'd get a slightly different result running a USD-EUR trade with a party in France versus e.g. Germany or the U.K.