At The Opening Order is an order that stipulates that the security is to be bought or sold only at the opening of the market, or as close to the opening as is reasonable, or not at all.
Applying "At The Opening Order" to Securities Exams:
An investor may wish to buy or sell a security at the open of the market’s regular hours. If the order is not executed on the opening the order will be canceled. The investor may place the order as a market on open or limit on open order. If the security is listed on NASDAQ the order will be part of the opening cross.