ACI Dealing Certificate (#260)

Which of the following is the best description of a “broken trade”?

when a trade has been agreed to with dates (maturities) different from the standard dates
when one of the parties to the deal unilaterally decides to withdraw from the on-going transaction
when, due to a system break, one or both parties to the deal chooses to withdraw from the ongoing transaction
when, due to a system break, one or both parties to the deal are unclear as to whether the deal has been done