Then, as one potential comes up and the other potential comes down, a current imbalance results in the output stage such that theres more current being sourced or sinked, depending upon {TAIL ~ the direction} of {HEAD ~ the imbalance} 
Then , as one potential comes up and the other potential comes down , a current imbalance results in the output stage such that there s more current being sourced or sinked , depending upon { TAIL ~ the direction } of { HEAD ~ the imbalance }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH HEAD HEAD HEAD HEAD HEAD HEAD