dirty float

It is also known as a dirty float.

However, since central banks frequently intervene to avoid excessive appreciation or depreciation, these regimes are often called managed float or a dirty float.

Meanwhile, the gap between the official and free-market rates is to be gradually reduced through a "dirty float," under which the Central Bank will intervene and support the currency as necessary.

The mere expectation or rumor of a central bank foreign exchange intervention might be enough to stabilize a currency, but aggressive intervention might be used several times each year in countries with a dirty float currency regime.

It will often have some influence over any official or mandated exchange rates: Some exchange rates are managed, some are market based (free float) and many are somewhere in between ("managed float" or "dirty float").