Stop-if-Offered orders are commonly used to sell the specified instrument in a falling market. If the price level specified is actually offered in the market, the order will be filled at the price bid by the bank.
For example, if you bought USDJPY at 132.00, with a Stop Offer at 131.50, your position would be closed (USD vs. JPY would be sold) if the Offer price hits or breaches 131.50 (in other words, if 131.50 or below is offered).
We recommend the use of Stop-if-Offered orders only to sell Forex positions.
The use of Stop-if-Offered to buy Forex positions can result in positions being prematurely closed if a market event causes the Bid/Ask spread to widen for a short duration.