I always thought the CME FX contracts had fifo matching since like forever.. are you sure this is a recent change? BTW, they are not discussing ordermatching algorithm. The fifo-rule they are refering to prevents being long and short in the same ccy-pair at the same time. Which is sort of pointless. The NFA introduced this rule for retail fx firms some time ago. Now the position is netted like in every other market, and some people do have a problem with that, because they cant do what they refer to as "hedging".