Que significa este condigo AS2

[anthony9564]

stop();

_quality = "BEST";
Stage.scaleMode = "noScale";


onEnterFrame = function() {
LB = getBytesLoaded();
TB = getBytesTotal();
PC = (LB/TB)*100;

loaderbar.setbar(PC);

if(TB>4 && PC == 100) {
delete onEnterFrame;
gotoAndPlay("initialize")
}

}