Day-Around Order
  
Ever place an order with a friend going to the donut shop for a coffee and a raspberry jelly donut, but to get an apple jelly donut if the shop has run out of raspberry? Last thing you want is the coffee without the donut.
A Day-Around Order is a similar kind of securities order. It gives a contingency in order to get an execution done, since orders have to be followed explicitly by law, and a previous order must be cancelled before a new order replaces it. If, say you wished to buy 100 shares of a stock with a limit order of $5, but news comes out before the open, and that stock opens at $5.50 and starts to climb, you could put a Day-Around-Order that adds a $5.65 limit for the 100 shares. This allows for the cancelation for compliance purposes, and the execution to be completed so you still get your shares.
A market order could work to get you executed, but then you would automatically get filled if the stock opened perhaps at $6, which might be higher than your acceptable entry point.