Question on MT5

There are more than 5 - there are 8:
ORDER_TYPE_BUY
ORDER_TYPE_SELL
ORDER_TYPE_BUY_LIMIT
ORDER_TYPE_SELL_LIMIT
ORDER_TYPE_BUY_STOP
ORDER_TYPE_SELL_STOP
ORDER_TYPE_BUY_STOP_LIMIT
ORDER_TYPE_SELL_STOP_LIMIT

But why do you ask? This info is available in the MQL Editor help files.