# Order types (options)

Currently only limit orders are accepted by the matching engine.

Though for options trading the platform supports 2 advanced order types. The order book keeps prices in BTC, the options are priced in BTC. But it is possible through the order form to submit **volatility orders** and **constant USD value orders**.

Filling the options order form, you can choose to determine the price in 3 ways: giving the price in BTC, giving the price in USD, and giving the price in Implied Volatility.

In the case of USD price and Implied Volatility price, the Deribit engine will continuously update your order as to keep respectively the USD value and the Implied Volatility at the fixed value as given in the order form.

**Fixed USD price orders** are useful when a trader has decided that he wants to pay X dollars for a certain option. Due to changing exchange rate of USD and Bitcoin, this value is not constant in BTC. But as the order book works only with BTC (there is no other currency on the platform), to keep the same value in USD for your order, the order will be continuously monitored and edited by the pricing engine. The Deribit Index is used to determine the BTC price of the option.

**Volatility orders** are yet a more advanced order form, where the implied volatility of the order will remain constant. This makes it possible to even make markets in some options series without further market maker applications. Automatic hedging with futures is currently not yet supported but is on the roadmap. Black-Scholes model or european options is used to determine prices.

Fixed USD and Volatility orders can be changed by pricing engine maximum once every 6 seconds, because Deribit index updates every 6 seconds.

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