int OrderSend	(	string	symbol,
		int	cmd,
		double	volume,
		double	price,
		int	slippage,
		double	stoploss,
		double	takeprofit,
		string	comment = null,
		int	magic = 0,
		DateTime	expiration = default(DateTime),
		int	arrow_color = 0
	)

The main function used to open market or place a pending order

Parameters

symbol	Symbol for trading
cmd	Operation type. It can be any of the following values: OP_BUY Buy operation OP_SELL Sell operation OP_BUYLIMIT Buy limit pending order OP_SELLLIMIT Sell limit pending order OP_BUYSTOP Buy stop pending order OP_SELLSTOP Sell stop pending order
volume	Number of lots
price	Order price
slippage	Value of the maximum price slippage in points
stoploss	Stop loss level
takeprofit	Take profit level
comment	Order comment text. Last part of the comment may be changed by server
magic	Order magic number. May be used as user defined identifier
expiration	Order expiration time (for pending orders only)
arrow_color	Color of the opening arrow on the chart. If parameter is missing or has CLR_NONE value opening arrow is not drawn on the chart

Returns

Returns number of the ticket assigned to the order by the trade server or -1 if it fails.
To get additional error information, one has to call the GetLastError() function

At opening of a market order (OP_SELL or OP_BUY), only the latest prices of Bid (for selling) or Ask (for buying) can be used as open price.
If operation is performed with a security differing from the current one, the MarketInfo() function must be used with MODE_BID or MODE_ASK parameter
for the latest quotes for this security to be obtained.
Calculated or unnormalized price cannot be applied. If there has not been the requested open price in the price thread or it has not been normalized
according to the amount of digits after decimal point, the error 129 (ERR_INVALID_PRICE) will be generated. If the requested open price is fully out
of date, the error 138 (ERR_REQUOTE) will be generated independently on the slippage parameter. If the requested price is out of date, but present
in the thread, the order will be opened at the current price and only if the current price lies within the range of price+-slippage.
StopLoss and TakeProfit levels cannot be too close to the market. The minimal distance of stop levels in points can be obtained using the
MarketInfo() function with MODE_STOPLEVEL parameter. In the case of erroneous or unnormalized stop levels, the error 130 (ERR_INVALID_STOPS)
will be generated. A zero value of MODE_STOPLEVEL means either absence of any restrictions on the minimal distance for Stop Loss/Take Profit
or the fact that a trade server utilizes some external mechanisms for dynamic level control, which cannot be translated in the client terminal.
In the second case, GetLastError() can return error 130, because MODE_STOPLEVEL is actually "floating" here.
At placing of a pending order, the open price cannot be too close to the market. The minimal distance of the pending price from the current
market one in points can be obtained using the MarketInfo() function with the MODE_STOPLEVEL parameter. In case of false open price of a pending
order, the error 130 (ERR_INVALID_STOPS) will be generated.
Applying of pending order expiration time can be disabled in some trade servers. In this case, when a non-zero value is specified in the expiration
parameter, the error 147 (ERR_TRADE_EXPIRATION_DENIED) will be generated.
On some trade servers, the total amount of open and pending orders can be limited. If this limit has been exceeded, no new order will be opened
(or no pending order will be placed) and trade server will return error 148 (ERR_TRADE_TOO_MANY_ORDERS).