The currency band is a system of exchange rates by which a floating currency is backed by hard money.
Additional meaning of Currency band:
A country selects a range, or "band", of values at which to set their currency, and returns to a fixed exchange rate if the value of their currency shifts outside of this band. This allows for some revaluation, but tends to stabilize the currency's value within the band. In this sense, it is a compromise between a fixed (or "pegged") exchange rate and a floating exchange rate.