Various constants used for programming trading strategies are divided into the following groups:
What's new in MQL5
The new platform features the netting accounting system allowing users to trade on exchange markets. In this regard, MQL5 contains deals and positions providing data on the current account status and performed trading operations. The platform also features new properties allowing you to form trading orders considering the specification of new financial instruments, as well as get data on deal's type and direction. The transaction time for orders, positions and deals is now displayed to the nearest millisecond. You can use not only the Magic Number, but also position ID to analyze trading.
Trading itself in MQL5 can now also be arranged in a new way based on the control of transactions using event handling. You do not need to survey the state of pending orders and open positions on your own anymore. The OnTradeTransaction() handler receives all changes on a trading account: activated orders, performed deals, opened positions, etc. You only need to analyze data on a received transaction and respond to it in accordance with your trading system logic.
The functions for working with the Depth of Market are meant for scalping and arbitration strategies. These functions allow you to receive all changes in buy and sell orders from the trade server continuously and without delay. New constants help you analyze the flow of quotes and performed deals by all selected instruments. The fast MQL5 language and asynchronous operations allow you to make trading decisions in real time with no delay.