Here is what Firstrade offers: This is their help section
Select the Order Type from the radio buttons, and enter the price desired for that corresponding type of order if it is required. If a value is not required in a box, you will not be able to type in it.
Market - An order to be executed immediately at the best available price. Market orders cannot be canceled via the internet. In order to cancel a market order before 9:30 a.m. EST please call and speak with one of our brokers. Market orders cannot be canceled between 9:30 a.m. - 4:15 p.m. EST.
Limit - An order for which you set a maximum price you are willing to pay as a buyer, or a minimum price you are willing to accept as a seller.
Stop - A stop order is activated and becomes a market order once the stock trades at or through the stop price specified by you. Once the order is activated, you are guaranteed execution, but there is no guarantee of the execution price. Stop orders for NASDAQ stocks are triggered by the Bid or Ask price.
Stop Limit - A stop limit order is similar to a stop order in that a stop price will activate the order. However, once activated, the stop limit order becomes a limit order and can only be executed at the limit price specified or at a better price. Thus, you are not guaranteed an execution with a stop limit order.
***In the case of Stop orders and Stop Limit orders, the Stop price entered must be above the current price in the case of buy orders and below the current price in the case of sell orders. You cannot place Stop or Stop Limit orders for Over-The-Counter Bulletin Board (OTC-BB) stocks, Small Cap stocks or Foreign Stocks.
Those are the rules that I live by....not as flexible as Scott Trade.