[MT4/MQL4] Order Type / 訂單屬性

ID	Value	Description
OP_BUY	0	Buy operation
OP_SELL	1	Sell operation
OP_BUYLIMIT	2	Buy limit pending order
OP_SELLLIMIT	3	Sell limit pending order
OP_BUYSTOP	4	Buy stop pending order
OP_SELLSTOP	5	Sell stop pending order

Ref: https://docs.mql4.com/constants/tradingconstants/orderproperties