求解释下列代码的意思

onClipEvent (enterFrame) {
if (this.hitTest(_root.mv)) {
if (this._currentframe == 2) {
_root.scro += 0;
} else {
this.unloadMovie();
_root.scro += 10;
}
with (_root.mv) {
yStep *= -1;
xStep *= 1;
}
}
tname = getProperty("", _name);
if (length(tname) == 3) {
this.gotoAndStop(2);
if (this.hitTest(_root.mv)) {
this.gotoAndStop(1);
}
}
}