Good Til Cancelled (GTC) -This is an order that is valid and working in the marketplace until cancelled by the customer or filled. Unless specified GTC, unfilled orders expire at the end of the trading day.
DAY -This is an order that is valid and working during the standard trading session
Fill-or-Kill (FOK) -This is an order that is either immediately filled in its entirety or completely canceled if it is not filled.
Immediate-or-Cancel (IOC) -This is an order requiring that all parts of the order be executed immediately after it has been brought to the market. Any portions not executed immediately are automatically cancelled.