Market orders are unlimited buy or sell orders that shall be executed at the next price determined.
The probability of execution is highest with Market Orders. Traders use Market Orders when orders need to be executed as quickly as possible.
Limit orders are bid/ask orders, which are to be executed at their specified limit or better.
Market-to-limit orders are unlimited bid/ask orders, which are to be executed at the auction price or in Continuous Trading at the best limit in the order book.
Outside of call phases, market-to-limit orders are only accepted if this limit is represented by at least one limit order and if there is no market order on the other side of the book. Any unexecuted part of a market-to-limit order is entered into the order book with a limit equal to the price of the first partial execution.