There are three order execution modes in the client terminal:
Instant Execution In this mode, the order is executed at the price offered to the broker. At sending the order to be executed, terminal sets the current prices in the order. If broker accepts the prices, the order will be executed. If not, the so-called "Requote" will occur: Broker returns prices at which the order can be executed.
Execution on Request In this mode, the market order is executed at the price previously received from the broker. Prices for a certain market order are requested from the broker before the order is sent. When the prices comes, order execution at the given price can be either confirmed or rejected.
Execution by Market In this order execution mode, broker makes a decision about the order execution price without any additional discussion with the trader. Sending of the order in such a mode means advance consent to its execution at this price.
Attention: Execution mode for each security is defined by the brokerage company.