"...Currency depreciations or appreciations that change the relative competitiveness of producers in different countries are undesirable from a global perspective if they lead to relative prices that do not reflect the true relative costs of production. From this standpoint, “external balance” does not mean that trade balances should be zero, but rather that global resources are allocated efficiently. The implications of this insight for the role of the exchange rate in monetary policy are explored here." (Quoted from paper)