TWELVE YEARS HAVE PASSED since the advent of generalized floating in March 1973, and by now considerable experience has accumulated with the operation of the present mixed system. Under this system, the currencies of the largest countries float, in some cases jointly with other major currencies, while most other countries continue to have exchange arrangements involving pegs or other mechanisms that limit exchange rate flexibility. Countries with floating exchange rates often try to influence them through various means, but unlike the other countries they do not try to maintain their rate at a particular level (which in arrangements such as crawling pegs may be changes frequently) through intervention or restrictions on exchange transactions.