All means of transportation within the city accept both Mexican Peso and U.S. dollar as payment currencies, but no other foreign currencies.

So the euro is bound to grow and its use is bound to become more widespread as a trading currency and a payment currency and, also, a reserve currency.

Iranian officials have said for months that more than half the OPEC member's customers switched their payment currency away from the dollar as Tehran seeks to diversify its reserves, but news of the Zhenrong change is the first outside confirmation.