This input represents the number of pips a pending order will move away without opening, if their price is reached BUT pending order open conditions give a false signal (conditions are not true at that time). This way, since the pending order could not be opened due to unfavorable conditions, even if the price follows the same trend (which would mean a shift away from the pending order triggering price) the pending order has the possibility of opening because the expert advisor will try again at the number of fallback pips (the Pending Orders Fallback Pips value) away from the last attempt price.

It is also important to mention that this process can happen several times, basically whenever the pending order open conditions are set and are not favorable at the same time, thus creating levels each time. Due to this, there is also the inverse to the fallback movement, which is optionally configured by the Pending Orders Return Margin and that will return to the original price the pending order was set to open at, in a opposite and gradual process also based on levels (see Pending Orders Return Margin  ).

Note that this input is only valid when the proper Pending Buy/Sell Open Condition   inputs are set. Setting this input to zero (0), disables this feature.
Imagine the following scenario: The current market price for EURUSD is 1.3500 and a new buy pending order is set to open 15 pips away from that price, that is, 1.3515. Now consider that you have the Pending Buy Open Condition   input set with a condition like iMACD(BAR)>VAL(0), meaning, in this particular case, that the bar value of the MACD indicator should be greater than 0. In addition to that, you have the Pending Orders Fallback Pips set to 10. Now consider that the price of 1.3515 is reached (which would mean the expert advisor would try to open the buy pending order) but the MACD indicator conditions are not favorable at that time with the condition set in the Pending Buy Open Condition  ​ input. Since you have Pending Orders Fallback Pips set to 10, the pending buy order open price will be moved away 10 pips to the price of 1.3525, so that if the trend remains favorable to our strategy, a new opening attempt for that pending order will be made​​.