The orders are locked in a smart contract in the form of an UTxO, and can be unlocked by matchmakers only for a trade that satisfies the trader's demanded limit price. An order may be partially filled, resulting in a new order that buys or sells the remaining token amount. A pending order may be canceled at any time by its creator, unless it has been completely filled already. If it has been partially filled, a cancel retreives the remaining order and the part of the order that has been filled already.