Gold coin standard, gold bar standard, gold exchange standard, of course, after the Bretton Woods system, the fixed ratio of dollar to gold is also similar to the gold standard.

The double standard system of gold and silver is a monetary system in which both gold and silver are standard currencies. The multiple standard system is divided into three forms: (1) "parallel standard system", that is, the system of gold and silver circulating according to actual value;

(2) It is a "double standard system",

That is, the system of gold and silver circulating separately according to the price ratio stipulated by the state;

(3) Lameness standard system. The dual standard of gold and silver is an unstable monetary system.